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Andrew Huberman (00:00):

Welcome to the Huberman Lab Podcast, where we discuss science and science-based tools for everyday life.


I’m Andrew Huberman, and I’m a professor of neurobiology and ophthalmology at Stanford School of Medicine. Today, my guest is Dr. Rhonda Patrick. Dr. Patrick is known to some of you as a podcaster and one of the premier educators in the landscape of mitochondria, metabolism, stress, and other aspects of brain and body health. Her podcast, Found My Fitness, is one of the premier podcasts in the world for disseminating knowledge about how the brain and body work and how we can use behavioral tools, micronutrients, supplements, and other protocols in order to maximize our immediate and long-term health. Dr. Patrick did her formal training in cell biology, exploring the links between mitochondrial metabolism, apoptosis, which is naturally occurring cell death, which is a healthy form of cell death that occurs in our brain and body throughout the lifespan, and cancer biology.


She then went on to do postdoctoral training with Dr. Bruce Ames, investigating the effects of micronutrients, meaning vitamins and minerals, and how they affect metabolism, inflammation, DNA damage, and the aging process. She has published landmark review articles and primary research, meaning original research articles, in some of the premier journals in the world, including Science, Nature Cell Biology, Trends in Cell Biology, and FASEB. Indeed, Dr. Patrick is an expert in an extraordinarily broad range of topics that impact our health. For today’s episode, we focus primarily on the major categories of micronutrients that are essential for brain and body health.


I have to confess that before the discussion with Dr. Patrick, I was aware of only one of the categories of micronutrients that we discuss. And so you’ll notice that I am wrapped with attention throughout the discussion. And I think that you’ll want to have a pen and paper handy because she offers not only a very clear understanding of the biological mechanisms by which other micronutrients operate, but some very clear and actionable tools and items that we can all embark on if we are to optimize our brain and body health. We also discuss behavioral protocols.


Dr. Patrick is well-known for her understanding of the scientific literature on sauna and the use of heat and cold for optimizing things like metabolism, longevity, cardiovascular health. And I’m delighted to say that we discussed that as well and how behavioral protocols can interface with supplement-based and nutritional protocols. I’m confident that you’ll learn a tremendous amount of information from Dr. Patrick, much of which is immediately actionable. And if you’re not already following and listening to her excellent podcast, you’ll absolutely want to do that. It’s is the website where you can get access to that podcast. It’s also on Apple and Spotify and YouTube as foundmyfitness. Dr. Patrick also has a terrific newsletter that I recommend signing up for. It’s slash newsletter is where you’ll find it. And it includes research on fasting, micronutrients, sleep, depression, fitness, longevity, and far more, along of course with actionable protocols. I’m pleased to announce that the Huberman Lab Podcast is now partnered with Momentous Supplements. Our motivation for partnering with Momentous is to provide people one location where they can go to access the highest quality supplements in the specific dosages that are best supported by the scientific research and that are discussed during various episodes of the Huberman Lab Podcast. If you go to slash Huberman, you will see those formulations. I should mention that we are going to add more formulations in the months to come.


And you will see specific suggestions about how best to take those supplements, meaning what dosages and times of day, and in fact, how to combine those supplements with specific behavioral protocols that have been discussed on the podcast and are science supported in order to drive the maximum benefit from those supplements. And many of you will probably also be pleased to learn that Momentous ships not just within the United States, but also internationally. So once again, if you go to slash Huberman, you will find what we firmly believe to be the best quality supplements in the precise dosages and the best protocols for taking those supplements, along with the ideal behavioral protocols to combine with those supplement formulations. Before we begin, I’d like to emphasize that this podcast is separate from my teaching and research roles at Stanford. It is, however, part of my desire and effort to bring zero cost to consumer information about science and science related tools to the general public.


In keeping with that theme, I’d like to thank the sponsors of today’s podcast. Our first sponsor is Athletic Greens. Athletic Greens is an all-in-one vitamin mineral probiotic drink.


Been taking Athletic Greens since 2012, so I’m delighted that they’re sponsoring the podcast. The reason I started taking Athletic Greens and the reason I still take Athletic Greens once or twice a day is that it helps me cover all of my basic nutritional needs. It makes up for any deficiencies that I might have. In addition, it has probiotics, which are vital for microbiome health. I’ve done a couple of episodes now on the so-called gut microbiome and the ways in which the microbiome interacts with your immune system, with your brain to regulate mood, and essentially with every biological system relevant to health throughout your brain and body. With Athletic Greens, I get the vitamins I need, the minerals I need, and the probiotics to support my microbiome. If you’d like to try Athletic Greens, you can go to slash Huberman and claim a special offer. They’ll give you five free travel packs plus a year supply of vitamin D3K2.


Our ton of data now showing that vitamin D3 is essential for various aspects of our brain and body health. Even if we’re getting a lot of sunshine, many of us are still deficient in vitamin D3. And K2 is also important because it regulates things like cardiovascular function, calcium in the body, and so on. Again, go to slash Huberman to claim the special offer of the five free travel packs and the year supply of vitamin D3K2. Today’s episode is also brought to us by InsideTracker. InsideTracker is a personalized nutrition platform that analyzes data from your blood and DNA to help you better understand your body and help you reach your health goals. I am a big fan of getting regular blood work done.


Trying to do it as much as I can afford for years. The reason is that many of the factors that impact our immediate and long-term health can only be discovered from a quality blood test. With most blood tests and DNA tests, however, you get information back, but not a lot of information about what to do with those numbers. With InsideTracker, they give you a lot of specific recommendations as to lifestyle factors and nutrition factors, supplementation factors, things you may want to add to your life or things you may want to delete from your life in order to bring the numbers into the ranges that are best for your immediate and long-term health.


There’s simply no replacement for these kinds of data. And your data are the most important data to you and quality blood tests and DNA tests are the way to access them. If you’d like to try InsideTracker, go to slash Huberman to get 20% off any of InsideTracker’s plans. That’s slash Huberman to get 20% off. Today’s episode is also brought to us by Thesus. Thesus makes what are called nootropics, which means smart drugs.


And to be honest, I am not a fan of the term nootropics. I don’t believe in smart drugs in the sense that I don’t believe that there’s any one substance or collection of substances that can make us smarter. I do believe based on science, however, that there are particular neural circuits and brain functions that allow us to be more focused, more alert, access creativity, be more motivated, et cetera. That’s just the way that the brain works. Different neural circuits for different brain states. Thesus understands this. And as far as I know, they’re the first nootropics company to create targeted nootropics for specific outcomes. I’ve been using Thesus for more than six months now, and I can confidently say that the nootropics have been a total game changer. My go-to formula is the clarity formula, or sometimes I’ll use their energy formula before training. To get your own personalized nootropic starter kit, go online to slash Huberman, take a three-minute quiz, and Thesus will send you four different formulas to try in your first month. That’s slash Huberman, and use the code Huberman at checkout for 10% off your first order. I’m pleased to announce that the Huberman Lab Podcast is now partnered with Momentous Supplements. We often talk about supplements on the Huberman Lab Podcast, and while supplements aren’t necessary for everybody, many people derive tremendous benefit from them for things like enhancing the quality and speed with which you get into sleep, or for enhancing focus, or for hormone support.


The reason we partnered with Momentous Supplements is several fold. First of all, their supplements are of the absolute highest quality. Second of all, they ship internationally, which is important because many of our podcast listeners reside outside the US. Third, many of the supplements that Momentous makes, and most all of the supplements that we partnered with them directly on are single ingredient formulations. This is important for a number of reasons. First of all, if you’re going to create a supplement protocol that’s customized for your needs, you want to be able to figure out which supplement ingredients are most essential and only use those. And supplements that combine lots of ingredients simply won’t allow you to do that.


So in trying to put together a supplement protocol for yourself that’s the most biologically effective and cost effective single ingredient formulations are going to be the most useful. If you’d like to see the supplements that we partnered with Momentous on, you can go to slash Huberman. And there you’ll see many of the supplements that we’ve talked repeatedly about on the Huberman Lab podcast episodes. I should mention that the catalog of supplements that are available at slash Huberman is constantly being expanded. So you can check back there slash Huberman to see what’s currently available. And from time to time, you’ll notice new supplements being added to the inventory. And now for my discussion with Dr. Rhonda Patrick.


Rhonda, welcome. This has been a long time coming, even longer than you know, because even before we discussed you coming on this podcast as a guest, I’ve been watching your content for a very long time. So I want to start off by saying thank you. You were the spearhead to break through from academic science to public education. So I consider you first in and the rest of us are just in your wake. So thank you for that. That’s been.

Rhonda Patrick (10:17):

Oh, that is so kind. Thank you. Thank you so much. Well, it’s absolutely true. I am so excited to be here having a conversation with you.

Andrew Huberman (10:23):

Thank you. It’s absolutely true. If anyone does their research, they will realize that the statement I just made is absolutely true. And there isn’t even a close second. You know, any other public facing educators that have formal science training and do regular posting of content came in several years after you initiated it.


So we’re all grateful. I have so many questions, but I want to start off with a kind of a new, but old theme that you’re very familiar with. So temperature is a powerful stimulus, as we know for biology. And you’ve covered a lot of material related to the utility of cold, but also the utility of heat. And as I learn more and more from your content and from the various papers, it seems that there’s a bit of a conundrum in that cold can stimulate a number of things like increases in metabolism, brown fat, et cetera, et cetera. Hopefully you’ll tell us more about those, but heat seems to be able to do a lot of the same things. And I wonder whether or not the discomfort of cold, deliberate cold exposure and the discomfort of heat might be anchoring to the same pathway. So would you mind sharing with us a little bit about what happens when we get into a cold environment on purpose and what happens when we get into a hot environment on purpose? And I’m hoping that this might eventually lead us to some point of convergent understanding. So if you would.

Rhonda Patrick (11:53):

I would love to, let’s take a step back. And I think you brought up a really important point here. And I think that point has to do with the intermittent challenging of yourself and whether that is through temperature changes like cold or heat, or through other types of stressors, like physical activity, or perhaps even dietary compounds that are found in plants. These are things like polyphenols or flavanols. Humans, we evolved to intermittently challenge ourselves.


And before we had Instacart where you could basically just get your food delivered to you, before the industrial revolution occurred, we were out hunting. And I say we, not us, but humans. We were out gathering, we were moving, and we had to be physically fit. You couldn’t catch your prey if you were in a cold environment or catch your prey if you were a sedentary slob, right? We’re moving and you had to pick your berries, you had to move. And so physical activity was a part of everyday life. And caloric restriction or intermittent fasting was also a part of it. This is another type of challenge. We didn’t always have a prey that we caught, or maybe temperatures were such that there was nothing for us to gather, right? So food scarcity was something common, as well as eating plants. So getting these compounds that I mentioned. So these are all types of stress, intermittent challenges that activate genetic pathways in our bodies. These are often referred to in science as stress response pathways because they respond to a little bit of stress. Physical activity is strenuous. Fasting is a little bit stressful. Heat, cold, these things are all types of little intermittent challenges.


And there is a lot of crosstalk between these stressors and the genetic pathways that they activate. And these genetic pathways that are activated help you deal with stress. And they do it in a way that is not only beneficial to help you deal with that little stressor, exercise or heat, it stays active and it helps you deal with the stress of normal metabolism, normal immune function happening, just life, aging, right? So this concept is referred to as hormesis, right? This is a little bit of stressful challenge that activates these stress response pathways in a beneficial way that is a net positive that actually has a very profound antioxidant, anti-inflammatory response or whatever the response is. It could be the production of more stem cells. These are cells that help regenerate different cells within tissues or something like autophagy, which is a process that can clear away all the gunk inside of our cells, pieces of DNA, protein aggregates.


So you’ll find that these stress response pathways are activated by a variety of stressors. So for example, one pathway is called heat shock proteins. And as their name would apply, one would go, oh, they’re activated by heat. Well, correct, they are activated very robustly by heat. And we can talk about that. But you can eat a plant like broccoli sprouts, which is high in something called sulforaphane. This is a compound that is sort of like a hormetic compound or as David Sinclair likes to say, it’s a xenohormetic compound. I love that, I love that term.


And it activates heat shock proteins, among other things. It also activates a very powerful detoxification pathway called NRF2, which helps you detoxify things like carcinogens that you’re exposed to. Well, guess what? Heat activates that. So what I’m getting at is there is overlap. Like cold also activates heat shock proteins. You’re like, really, cold? Yes, it activates. These are stress response pathways and they are activated by various types of stressors. Now, you’re gonna more robustly activate heat shock proteins from heat versus cold, but there is some overlap. So I think that sort of forms a foundation there.

Andrew Huberman (15:51):

Yeah, that’s very helpful. And it brings to mind in the context of the nervous system, you know, you only have a small kit of neurochemicals to work with. There isn’t dopamine for Netflix and then dopamine for relationship and dopamine for work, et cetera. Dopamine is a generic pathway by which motivation, craving, and pursuit emerge, et cetera. Just like adrenaline is a generic theme of many different behaviors. And it seems that it is the job of biological systems to be able to take a diverse range of inputs, even unknown inputs. Like we don’t know what technology will look like in three years, but you can bet that some of those novel technologies will tap into the very systems that I’m talking about now. And there certainly will be other stressors to come about that will tap into these pathways. I have two questions related to what you just said before we talk a little bit more about cold and heat. You mentioned plants as a route to creating intermittent challenge.


There’s a lot of debate, mostly online, about whether or not plants are our friends or plants are trying to kill us. The extreme version from the carnivore types, pure carnivore diet types, is that plants are trying to kill us. From the plant-based diet folks, it seems like it’s more about what’s healthy for the plant and animals and maybe for us. But if we set aside that argument and we just raise the hypothesis that plants have compounds that are bad for us, but maybe by consuming them in small amounts, they’re creating this hormesis type scenario. So then I think we conceivably solve the problem.


We could say, yes, plants are bad for us, but in small amounts, they provide this hormetic response and they’re good for us, right? So in the same way that too much heat is bad for us, too much cold is bad for us, can kill us, can kill neurons, but appropriately dosed in an intermittent challenge type of scenarios can be good for us. Is that how I should think about plants in these compounds? Do you think of them as good for us or as bad for us? They’re a very sharp blade and we want to use them potently.

Rhonda Patrick (17:56):

I actually, I think that it’s almost impossible. I mean, you’d have to eat nothing but the same plant all day, every day in large. I mean, the bioavailability of these compounds in the plants, they’re attached to a food matrix. You know, it’s not like taking it in a supplement form as well. It’s such that it’s very difficult to make it toxic.


Now, there are some cases, for example, if you eat cabbage, and I think there’s some group in Africa or somewhere that that’s all they eat is cabbage, and there is a goitrogen in cabbage. It’s not sulforaphane, it’s another compound, but that’s all they eat every day. Nothing but that. And they get, yeah, and they’re like iodine deficient on top of that. So, you know, I do think there’s, you can of course make, I mean, there are types of plants that are toxic in small quantities, right? I mean, hemlock, exactly.

Andrew Huberman (18:52):

So- We’ll kill you. Folks, don’t play this game with hemlock.

Rhonda Patrick (18:55):

But you’re not gonna get poison from eating, you know, you’re serving of broccoli at dinner, right? So, I mean, it depends on the plant. It’s, I don’t, these generalizations are kind of, they’re just not useful. And I think that a lot of people online, in the blogosphere, they gravitate towards them because it’s easier and it’s a lot more sensational.

Andrew Huberman (19:18):

I eat plants, meat, and starches. I’m one of those rare omnivores out there now. I feel like I’m a rare, or it’s rare to be an omnivore. But I think once you step out of the social media, as you said, the blogosphere, most people, I would say 99% of people on the planet are probably omnivores. Right. And someone will probably correct me, but I doubt the number falls below 98.

Rhonda Patrick (19:41):

I think if you look at data, you know, and when we have carnivore data, like I can’t wait to see it, but like right now it’s a lot of, okay, well, this is a lot of anecdotal evidence and there’s a good, there’s a lot of good starts with anecdotes, but like people change a thousand things at once and they don’t realize that, but they do. And so anecdotal data is only so good, right? It’s a starting point. And so we don’t really know long-term what carnivore diets are gonna do. They may be beneficial short-term. They may be beneficial for reasons of elimination of other things. Like who knows, right? Lots of possibilities. But I do think with respect to plants, you know, there’s so much evidence, like for example, sulforaphane is one that I really like because there’s just evidence that sulforaphane is a very powerful activator of the NRF2 pathway. And this is a pathway that regulates a lot of genes and a lot of genes that are related to like glutathione production, genes that are involved in detoxifying compounds that we’re exposed to from our food, like heterocyclic amines. In fact, there have been GWAS studies. So these are genetically, these are studies that are genome-wide associated studies for people listening that aren’t familiar. People have a variety of versions of genes. And we have a gene that’s able to make heterocyclic amines to basically detoxify it so it’s not as harmful.


And people that don’t have a certain version of that that’s doing it well are very prone to like colon cancer and increased cancer risk. But if they eat a lot of broccoli and cruciferous vegetables, it negates that risk because they’re getting sulforaphane, which activates a lot of the glutathione transfer, glutathione transferase and synthase genes. So glutathione’s a major antioxidant in our brain, in our vascular system, in our body basically. So, you know, there’s evidence that eating things like, you know, compounds that are like sulforaphane or broccoli or broccoli sprouts, which have like a hundred, up to a hundred times more sulforaphane than broccoli, are activating glutathione in the brain. There’s human evidence of that. I mean, that’s amazing.

Andrew Huberman (21:57):

That is amazing. In plasma, yeah. Sorry to interrupt. I just want to make sure when, so broccoli sprouts are different than broccoli. And you just told us that they have much, they’re much richer in these compounds. So note to self, I should have broccoli sprouts, not just broccoli. Can we cook the broccoli and still get these nutrients or do we have to eat it raw? I confess eating raw broccoli is really aversive to me.

Rhonda Patrick (22:21):

So the sulforaphane is formed from a compound called glucoraphanin, which is in the broccoli. And the enzyme that converted into sulforaphane is myrosinase and it’s heat sensitive. So you do somewhat lower the sulforaphane levels when you cook the broccoli. However, there was a study a few years back that showed adding one gram of mustard seed powder, ground mustard seed powder, which also contains the myrosinase enzyme, to your cooked broccoli, increases the sulforaphane by fourfold.

Andrew Huberman (22:55):


Rhonda Patrick (22:56):


Andrew Huberman (22:56):

this is great. Cause I confess, I like broccoli if it’s cooked to the appropriate density, not too mushy, but definitely not raw. The idea of eating raw broccoli to me just sounds horrible, but I like the way mustard seeds sound. So just a little bit of mustard seed powder added to the cooked broccoli can recover some of these compounds.

Rhonda Patrick (23:15):

Yes, so what I do is I will lightly steam my broccoli and then I add a little bit of my Kerrygold butter and then I add some mustard seed powder on the top of that. And it’s got a little kick, like it’s just a little spice, you know? And if you don’t taste that, it’s expired. Like it should have a little kick.

Andrew Huberman (23:34):

And because I know people will want to know how often and how much, you know, are you eating this every day or most days of the week?

Rhonda Patrick (23:41):

Well, I had shifted to supplementation with sulforaphane. I’ve admitted, I’m admitting right now that I’ve been terrible about it the past, like, I don’t know, six months or so.

Andrew Huberman (23:52):

The supplementation or the broccoli?

Rhonda Patrick (23:54):

Yes, the supplementation. And so there’s another way to get, there’s another compound and it’s actually called moringa. And Dr. Jed Fahey, who’s really the expert on sulforaphane, he’s a good friend of mine, he’s been on the podcast a couple of times, he basically thinks and, you know, has done a lot of research on moringa as well, that it’s like a cousin and it activates the NRF2 pathway similarly to sulforaphane. And so I’ve been buying this Kooli Kooli moringa powder. I don’t have any affiliation with them.

Andrew Huberman (24:29):

Kooli Kooli is a brand. Kooli Kooli is a brand. That you have no affiliation to. I have no affiliation.

Rhonda Patrick (24:33):

Okay. But Jed Fahey, he like has researched it like that specific brand. And so it’s like, it’s legit. You know, it’s like science-backed in terms of actually containing moringa and activating NRF2. And I add it to my smoothies. So that’s what I’ve been doing.

Andrew Huberman (24:49):

What are some dose ranges? So I- And of course we give the usual recommendations that people should talk to their physician, et cetera, et cetera. But if people are going to, what do you take? That’s always the, let’s take the David Sinclairian approach. What do you, where he’ll talk about what he does as a way to deal with this. And of course, everybody’s different and should, in all seriousness, should, anytime you add or delete something from your consumption, should consult some trusted healthcare professional, trusted by you. What, do you recall the dosages?

Rhonda Patrick (25:22):

I do a big heaping tablespoon.

Andrew Huberman (25:24):

So moringa, Kooli Kooli.

Rhonda Patrick (25:26):

Yeah, and it’s- It sounds like a song. It’s with a K, I know. But, you know, for people also listening, it’s like, well, why would I do that? You know, I mentioned the glutathione in the brain. I mentioned it in plasma. It’s been shown to lower DNA damage in people and white blood cells. It’s also been shown, there’s been several different studies in China. You know, in China, there’s a lot of air pollution. And I mentioned that, you know, it’s a very powerful activator, NRF2. And I know you’re familiar with NRF2, but NRF2 is like, it’s your transcription factor that is, it is binding to a little specific sequence in a variety of different genes, and it’s like turning them on, or in some cases, turning them off. It’s regulating what’s being activated or what’s not being activated or being turned off. And some of the genes are basically these detoxifying pathways. We talked a little bit about the glutathione, but there’s also ones that are involved in airborne carcinogens like benzene. So benzene is found in air pollution, I mean, cigarette smoke. If you’re smoking cigarettes still, like, please try to quit.

Andrew Huberman (26:28):

Yeah, you’re mutating your DNA. I mean, yeah. Just say nothing of the lung cancer, you’re mutating your DNA.

Rhonda Patrick (26:32):

And heart disease risk, heart disease risk. But anyways, people, and this has been repeated in more than one study, that literally after 24 hours of taking, can’t remember off the top of my head what the dose of sulforaphane from broccoli extract, broccoli seed extract was. Or broccoli sprouts extract, not the seed, it was the sprouts. Anyways, they started excreting like 60% benzene and acrolein. I mean, that’s something that we get in cooked food.

Andrew Huberman (26:59):

It’s coming out in their urine?

Rhonda Patrick (27:02):


Andrew Huberman (27:02):

Well, I’m not a smoker and I have to be honest, it’s rare that I hear of a supplement for the first time because I’ve been deep diving on supplements since I was in my teens. This is fascinating. And it brings me back to this question that we had before and I appreciate that you answered it very clearly. Plants have compounds that are good for us. They’re not just stressing us. They’re activating pathways that are reparative. That’s what I’m taking away from everything you’re telling me.

Rhonda Patrick (27:29):

Right. And that our bodies, we’re supposed to be getting that stress to have those pathways activated. Like it is, like, you know, right? I mean, this is conserved among different animals. Like this is something that is supposed to happen. And in our modern day world, we don’t have to eat plants. We don’t have to move anywhere or exercise. We don’t have to go through periods of not eating food because we can have it at our fingertips at any second. Right? So, I mean, we’ve got this conundrum of we’re never activating these stress response pathways that we’re supposed to activate. We’re supposed to.

Andrew Huberman (28:10):

I find that fascinating. And again, drawing a parallel to the nervous system. So what I’m hearing you say is that historically we would have to go through some stress, some confront cold or confront heat or confront effort or hunger and have to exercise essentially in order to obtain these compounds. And then those compounds are reparative. I feel that resembles the dopamine pathway. I always say, you know, there’s nothing wrong with dopamine. People think about dopamine hits as bad or dopamine is bad. There’s absolutely nothing wrong with dopamine. The problem is dopamine, especially high levels of dopamine, released without the need for effort to access that dopamine is problematic. So a line of cocaine gives you a ton of dopamine with no effort except to ingest the drug. Whereas working for four years or more to get your degree will release a lot of dopamine and a lot of cortisol along the way, as we know. And it’s considered a healthy accomplishment in most cases. A tremendous amount of, we’re approaching the spring and there’ll be a lot of graduations. Weddings are coming up now that the pandemic is kind of hopefully slowing.


And there’ll be a lot of dopamine. High levels of dopamine are great, but only after the effort of having done something in order to access it. And so that’s what I’m taking away from what you’re saying is that we need to go through this intermittent, the different types of intermittent challenge. And we are rewarded with particular compounds that are reparative, both for the challenge, but then make us stronger. It is, hormesis really is, it seems, a case of what doesn’t kill us makes us stronger. So you mentioned-

Rhonda Patrick (29:44):

Can I add to that one thing you just said? Because this has been shown with, for example, the sulforaphane in animal studies, you precondition, give the animal sulforaphane, and then you expose them to hypoxia or some kind of ischemic stroke condition, whatever they do to induce that. And the sulforaphane, it basically protects them.


Their precondition and their stress response pathways are primed, and so when they’re then exposed to the ischemic stroke, their outcomes are so much better, so much better than the animals that didn’t get the sulforaphane for eight hours before, whatever it was. And this has been shown in multiple animal studies, with sulforaphane specifically, in the brain. I know Dr. Mark Mattson, he’s often thought of as the intermittent fasting king, but he’s a neuroscientist, and he did publish some work and talks about sulforaphane as well.

Andrew Huberman (30:36):

I’m really glad you brought that example up, because many of the questions I get on social media and elsewhere are about traumatic brain injury, and TBI is just one example. And people always think, oh, sports, it’s football. Whenever you say TBI, people always think football, and I just want to just take a moment to editorialize. 90% or more of traumatic brain injury is construction work, at-home accidents.


Football players, hockey players, martial artists are a tiny fraction of the people who have TBI and concussion of various kinds. It just so happens that within those communities, many of them, 75% or more, experience those. So it’s salient within those communities, but concussion is prominent. People are always asking, what can I do in order to offset brain injury? I had a concussion two years ago, what can I do? And it’s been a tough question, because we really don’t have anything for them. I mean, you tell them, sleep well, eat well, exercise, but it sounds like some of these reparative pathways either should be explored in the context of brain injury, or I’m guessing are being explored in the context of brain injury.

Rhonda Patrick (31:44):

Yeah, so a couple of things there. One is that, I mean, traumatic brain injury, I mean, it’s terrible, but it’s also, it’s so interesting, because it’s also like literal real-time brain aging. Like, you know, like it’s, you’re able to like accelerate it and understand. So I often think of, when I think of traumatic brain injury, I think of so much overlap between Alzheimer’s disease and dementia and these neurodegenerative diseases, because there are a lot of similarities there, you know? And so sulforaphane, I personally think, and I do think there’s been some animal research with TBI, I mean, and sulforaphane, mostly preconditioning rather than treatment. So again, it’s like, well, I mean, if you’re gonna, if you want a healthy lifestyle thing and you’re a construction worker or you’re fill in the blank, that’s, you know, gonna, I mean, anyone that drives into a car, I mean, you’re at risk to some degree, right?

Andrew Huberman (32:37):

Bicycle. Bicycle, yeah. Around Stanford, we have, you know, I would say people demonize motorcycles, people demonize a lot of things, but moving fast through space on a small object next to a 3,000-pound vehicle, I mean, we’ve lost, we have a number of friends that have died, we have a number of people with traumatic brain injury. I’m not against cycling or cyclists, but it is, it’s a risky sport by any stretch. So in taking things like moringa or eating my broccoli sprouts, maybe cooking them a little less than I’m currently cooking them, putting on the mustard seed, is there evidence that, well, first of all, NRF2 is expressed in neurons, right? So those cells should be protected. Are there other cells of the body that could possibly gain protection from these pathways?

Rhonda Patrick (33:24):

Well, lungs, for one, but, you know, just even in plasma cells, I mean, I think it’s pretty, NRF2 is pretty ubiquitously expressed. Liver, so there’s, I mean, there’s so many animal studies that have looked at all those things. I try to kind of gravitate towards human ones because it’s a little, a lot more relevant.


But I think, you know, overall, like I mentioned, you know, DNA damage lower, it was like 24 or 34% lower in human blood cells after broccoli sprout powder supplementation. And I made a video on this like years ago, 2016 maybe, and I think I have like the references on there to exact amounts. I can’t remember. But it’s kind of an old video, it’s 2016. But I also had Jed on the podcast, and he did talk about this. But, you know, it’s also been shown in randomized controlled trials to help treat autism and autistic symptoms. And yet again, it’s doing interesting things in the brain. And I think it does have something to do with the oxidative stress and the glutathione, which would be relevant for TBI treatment. It hasn’t been shown empirically that that helps with treatment, but I do think someone could do that study. I think that it should be done, honestly, because it’s a low-hanging fruit. I mean, if there is any impact, and there is at least one preliminary study that glutathione is increased in the brain after humans are, you know, basically taking sulforaphane. So…

Andrew Huberman (34:52):

Which is really, for people listening, that’s so important because a number of compounds that people take in supplement form don’t cross the blood-brain barrier, or they get metabolized in ways that what’s listed on the bottle almost becomes irrelevant for what your cells actually experience. So that’s very reassuring. We will get back to heat and cold in this theme that I tried to service, but I just find this too interesting to diverge at this point from these themes. So what other compounds or micronutrients do you place in the top tier of useful, interesting…


There are animal studies, maybe there are hopefully also some human studies. We’ve talked about a few. I know you’ve talked a lot about omega-3 fatty acids. So if you had to do your kind of top three, your superstars of nutrients for the brain and body, it sounds like we’ve got one set. What would you put in alongside them?

Rhonda Patrick (35:45):

Omega-3, the marine omega-3 fatty acids. So these are found in marine types of, you know, animals, fish, cold water fish, fatty fish. So there’s three fatty acids. There’s one from a plant, and that’s often referred to as ALA. People call it short, alpha-linolenic acid. And then there’s eicosapentaenoic acid, or EPA, and docahexaenoic acid, which is DHA.

Andrew Huberman (36:11):

Yeah. I’m amazed you can pronounce two of the most difficult words to pronounce and spell right next to ophthalmology, which if you can spell it… I know people who have appointments in ophthalmology departments that don’t know how to spell ophthalmology. A little secret, there’s an extra P in there.


So the ALA, I’m not going to attempt to pronounce it because your pronunciation was perfect, of both of these two compounds, and you said are marine sources. So fish, so sardines, cod, this sort of thing, but what about krill? I’ve seen krill oil, and there was a few years back, people were saying krill is a better source for omega-3s than is fish oil. I took some krill oil capsules, made me itch all over, so I stopped.

Rhonda Patrick (36:55):

Do you have a shellfish allergy?

Andrew Huberman (36:56):

No, I don’t think so. I don’t think so. I’m not a big fan of shellfish, but I like, you know, I’ll have oysters every now and again, or shrimp or something, and feel fine.

Rhonda Patrick (37:04):

Yeah, we can talk about sources. So krill is a source mostly of a type of DHA and EPA that’s in phospholipid form. So it’s a phosphatidylcholine omega-3 fatty acid, and that’s different than most of the, well, if we’re talking about fish oil supplements, that’s a different story, but if you’re talking about comparing fish to eating krill,

Andrew Huberman (37:30):

we’re talking about the foods. Oh, I would never eat krill. Okay, are we talking about the supplements? Yes, I apologize. Krill supplement versus fish oil supplement, and if it fits in the conversation, talking about great sources of omega-3s in their whole form, I have a bad feeling you’re going to tell me sardines.

Rhonda Patrick (37:49):

Sardines are, yeah, they’re awesome.

Andrew Huberman (37:51):

Anyway, except for the taste.

Rhonda Patrick (37:54):

And for the potential contaminants, mercury, I think, was one. No, yeah, it was mercury. And Joe was telling me about, he used to eat sardines every day. Joe Rogan was telling me that he used to eat sardines every day, and then he had really high mercury levels, and I was really shocked, because sardines are low in the fish group. So the higher up you get, swordfish and sharks, really high mercury, because they’re eating all the other fish, right? But I think some brands, and if you look at Consumer Lab, Consumer Lab, it’s like a third-party site that I’m affiliated with, but I use them, because they do a lot of analysis of different foods and supplements, and so you can look at some of their sardines, and they have a list of ones that are pretty decent. But anyways, back to your question about fish oil supplements versus krill oil supplements. So one of the major differences is that fish oil supplements, if you get a high-quality one, it’s in a triglyceride form.


So you’ve got a glycerol backbone with three fatty acids, and that’s attached, and those are either DHA or the EPA.


Or if you have a lower-quality fish oil supplement, then you have what’s called ethyl ester form. And typically, the reason for that is when fish oil is purified, it’s run through this column with alcohol or something, they cleave it off the glycerol backbone, and then it’s just kind of easier to leave it like that than like re-esterifying it, which costs more money. So you can get it in ethyl ester form, which isn’t as bioavailable, and in fact, if you don’t take it with food, you’re gonna be in trouble. You’re not gonna absorb much of it at all.

Andrew Huberman (39:40):

Would you see this on the packaging? Is it gonna say it’s in this ethyl form?

Rhonda Patrick (39:44):

Some official brands will put it on their website, perhaps on their packaging, but most of the time, you’ll have to dig for it on the website and or call them. But I think for the most part, ones that are higher end will market it like triglyceride form. And it’s not that ethyl ester is bad, it just means take it with food. So one of the major prescription omega-3s out there is both of them, actually, Lavazza, which is a mixture of DHA and EPA, as well as Vasipa, which is a highly purified EPA. These are both prescribed by physicians to patients with hypertriglyceridemia, so high triglycerides, among other things, I think, maybe dysregulation of lipids as well.

Andrew Huberman (40:27):

This is amazing for people. So these are prescription drugs that are essentially very high potency purified omega-3s, but they’re given to people for lipid issues. So this is the treatment of issues with fat metabolism, by giving people fat. Just to really, I just want to push home, again, I’m not carnivore keto or anything, I’m an omnivore, but to just push home that we…


One thing that’s so wonderful that you’ve done over the years that you continue to do is to move away from these very broad sweeping statements about fat is bad. I mean, here’s a case where we’re saying fat is not only good, it can be used to combat issues with fat metabolism. And then fats are not just one thing, they’re many things. So anyway, I just didn’t want to put a little highlighter and a point of appreciation there and make sure that people are sensitized to the fact that if you hear that fat is bad, you have to ask what kind of fat, right? And here we’re talking about these omega-3s. Okay, so the triglyceride form can be taken with or without food and there’s prescription forms. I don’t know if I can get ahold of the prescription form, I don’t know if I can get ahold of the prescription form unless…

Rhonda Patrick (41:35):

You have high triglycerides. Or I have a friend with high triglycerides. It’s illegal folks, don’t share prescription drugs. Or you talk to your doctor and you say, I’m already taking this from… I mean, I don’t know how it works.

Andrew Huberman (41:46):

Anyways. What’s the dosage that you recommend people get?

Rhonda Patrick (41:49):

One way or another. All right, okay. So the dosage that physicians prescribed for high triglycerides, for example, is four grams a day.

Andrew Huberman (41:58):

Four. Four grams of EPA?

Rhonda Patrick (41:59):

Of, yes, of the vesipa. I think Lavazza is also prescribed at four grams a day. And you can get either of those from your physician. My father-in-law just got one of them prescribed because we were buying our own omega-3 for years and years. It’s like, hey, you can actually get this and health insurance can cover it. And it’s a really purified form. But you have to take it with food. That was the bottom line. I’ve totally gone on tangents, but you’re asking more interesting questions anyways.

Andrew Huberman (42:25):

Well, normally I ask about mechanism and then I talk about protocols, but in the- Or the why. Or the why. I mean, we haven’t gotten there yet. But I think that, and we definitely will get there, but I think a number of people nowadays are just really excited about what they can do for their health. And so here we’re just raising the importance of omega-3s and then we’ll definitely get to the why and the underlying.

Rhonda Patrick (42:44):

Yeah. I think four grams is, I mean, and in fact, Bill Harris, Dr. Bill Harris, he’s just one of the pioneers on omega-3 fatty acid research. He was on our podcast not, you know, last August. And he was saying the reason FDA chose that was literally just because how much they could get people to take. Like, it wasn’t like an upper end, like, oh, this is not, anything above that is unsafe. That wasn’t the case. I mean, it was just purely like cost and like, you know, compliance. So like what they can get into a pill, the amount they can get and how many pills they can get people to take.

Andrew Huberman (43:24):

I’m smiling because our good friend, Sachin Panda at the Salk Institute, who’s done a lot of important work on intermittent fasting and other incredible work on circadian rhythms, et cetera. When I was talking to him in preparation for an episode on intermittent fasting, I said, why the eight hour feeding window? And he said, well, the graduate student who ran those studies had a partner, I think it was a girlfriend, as I recall, hope I didn’t get that backward. And the partner said, listen, you can be in lab 10 hours a day, but you can’t be in lab 14 hours a day if you want this relationship to work. And so it was eight hours of feeding window plus some measurements and time to walk into the lab, park the car, et cetera. And so the eight hour feeding window that everyone holds so wholly was actually just born out of this relationship between these two graduate students. Had they been single, I was single all through graduate school or most of it anyway, and I lived in the lab. So if it’d been me, we’d all be, intermittent fasting would mean eating 14 hours a day. That was a joke, not a good one, but I just want to make clear I’m joking. But the point that you’re making is a really good one that the four gram amount is not a threshold based on anything except the threshold of people’s willingness to actually take the stuff. So, and I think that’s important for people to hear because so often we hear the eight hour feeding window, four grams of EPA, 150 minutes of cardio, and it’s really a question of what you can reasonably do in a study.

Rhonda Patrick (44:50):

So I take four grams a day. I take two in the morning, two grams in the morning, and I take two grams in the evening. I take my EPA in the morning and I take my DHA in the evening. You split them. I do. I don’t know if, I don’t think it’s necessary, not necessarily. I just happen to buy, I happen to get a certain fish oil supplement that’s like separates them. And so, like Lavazza, Lavazza is a great one and it’s all like in one and it’s easier.

Andrew Huberman (45:14):

What if someone doesn’t have a prescription? So I take over the counter fish oil. I know I feel better because I’ve done the experiment of going on and off. I take the mainly for, I don’t have depression, but my mood is better. My joints feel better. I just feel better. And I like to think that my platelets are slipperier and they’re cruising through any little obstructions in my veins or arteries. That’s the image I have in my head, but I don’t have any data to support that part.

Rhonda Patrick (45:40):

Yeah, I mean, so if you’re asking for like, where do people get these fish oil supplements?

Andrew Huberman (45:45):

Well, let’s say I look at the bottle and it says two grams per serving, but then I look and it’s 750 milligrams of EPA, right? Or 1,000 milligrams of EPA. Let’s say half of it is EPA. Then do I want to hit a threshold of EPA or a threshold of what’s listed on the bottle, right? On the front of the bottle. And because my understanding is that we need to hit a threshold level of EPA in order to derive these important benefits.

Rhonda Patrick (46:16):

I think two grams is a good threshold. Now, the International Fish Oil Standards, IFSO, they have a website where they do third-party testing of a ton of different fish oil supplements from around the world. And they measure the concentration of the omega-3 fatty acids in the actual supplement because nothing is ever what it says on the bottle. And then they also measure contaminants, so mercury, PCBs, dioxins, things that you’d find potentially in fish that are harmful to humans. And they also measure mercury and then oxidized fatty acids. So these omega-3 fatty acids are polyunsaturated fatty acids, which are extremely prone to oxidation. So please keep your fish oil in the refrigerator because it’s going to be a problem. So they measure the concentration of the fish oil

Andrew Huberman (47:06):

in the colder, yeah. They’re extremely prone. Mine’s in the cupboard, so now I know.

Rhonda Patrick (47:09):

The shelf life’s increased, lower oxidation. It makes perfect sense. Right. So anyways, they measure that. And I typically like to look for, they give you a total oxidation number. It’s called TOTOX, T-O-T-O-X, TOTOX is what we call it for short. And I like it to be at the least under 10, ideally under six, it’s really hard to find all the right mixtures of things.


But people can go to this website and they can browse through the products. I’ve put together an Excel sheet, which I have a YouTube little screencast that I’m yet to publish, press the publish button on. But it basically, you have to go back and check an update because these are from different lot numbers of the products. They do have up to like 20, 27 or something. So I’ve gone through and found my top picks of high EPA brands and high DHA brands if I were to buy some, the ones that I would choose because of the low total oxidation and the high concentration of either EPA or DHA. People can go and do this themselves.

Andrew Huberman (48:13):

It just takes some work. No, I’m glad that you did the work. I’m going to put up a tweet every week with you tagged until this list is published online. Sorry, Rhonda, but I’m going to do it. I know it’s very sadistic of me, but in service to the community and myself.

Rhonda Patrick (48:28):

And I chose five brands from each. And I try to find one in like Europe and one in Canada.

Andrew Huberman (48:34):

So there’s a great selection of US and other. I don’t want to do that work. And I trust you. So yeah, I try and get two grams per day of EPA from supplementation. I’ll now put it in the refrigerator. Mood is better. I made that decision mainly based on the data that I’m aware of, looking at comparison of people doing that anywhere from two to four grams of EPA per day compared to SSRIs, serotonin, selective serotonin reuptake inhibitors and treatment of depression. And I don’t want to take an SSRI if I don’t have to. And fortunately I don’t have to, but the data by my read are remarkable. People that take these things in sufficient doses, meaning the EPAs are able to get by with much lower dosages of SSRIs for depression relief, or in some cases to come off their SSRIs completely or avoid going on antidepressant medication. Now, of course, this is not something people should cowboy. Mental health issues are serious, but what other reasons, I’d love your thoughts on that on the mental health part. And so maybe you could tell us what are some things that getting two to four grams of EPA per day is going to help with in our brain and the rest of our body.

Rhonda Patrick (49:44):

So do you know, so I actually published a paper back in 2015 about the role of omega-3 and vitamin D in depression, bipolar disorder, schizophrenia, and impulsive behavior. But so like within that paper, like doing background research, and this was a review article, by the way, I was just connecting dots,

Andrew Huberman (50:06):

because I- No, I’m going to grab that. I confess I don’t know the paper, but I love quality reviews, because the references they’re in are so useful.

Rhonda Patrick (50:14):

Well, there’s a huge role for inflammation, the cause of inflammation and depression. And I think we did a short animated video on this as well, like years ago, back when I was publishing that work, where people are injected with lipopolysaccharide. I mean, this is something that we’re generating from our gut, mostly from our gut permeability, which happens a lot. Endotoxin, it’s also called, it’s endotoxin lipopolysaccharide, it’s basically the outer membrane of bacterial cells when bacteria die. So like when the immune cells in our gut come into contact with the bacteria, because we drank alcohol five days in a row or whatever, we release endotoxin, or something stressed us out, we release endotoxin into our body, and that causes inflammation. And so you can inject people with lipopolysaccharide and cause depressive symptoms. However, if you take those same cohort of people, give them EPA, and I think it was somewhere around two grams and then inject them with lipopolysaccharide. We’re establishing causation here, right? It totally, the depressive symptoms versus the placebo. So the placebo was saline control. So this was a placebo control because obviously it’s hugely important for depression. It ameliorated the depressive symptoms that was caused by lipopolysaccharide.

Andrew Huberman (51:30):

Amazing, and LPS, lipopolysaccharide, is no joke. Years ago, when I was working on thermal regulation, we would inject animals with LPS to induce fever. The vagus nerve registers the presence of LPS signals to these particular hypothalamic areas and cranks up body temperature, because basically it’s a signal that the body is infected, right? Amazing. So I will continue with my two grams per day. Maybe I’ll ramp it up to four. I’m not doing the DHA separately. There’s DHA in the same supplement. Is that okay?

Rhonda Patrick (52:07):

Yes, yeah, yeah. And to kind of, boy, we’ve got a lot of things to hit back on because one of your original questions was krill oil versus fish oil. And DHA specifically is, in phospholipid form, it’s more bioavailable. So our bodies, if you’re comparing exact quantity or concentration in triglyceride form versus phospholipid form, you will get more in your plasma cells, in your plasma, not plasma cells, in your plasma with krill oil. However, krill oil supplements are so low dose, like, I mean, good luck getting two grams of omega-3 from krill oil. And also krill oil supplements are notoriously rancid. I don’t know for whatever reason. Maybe that’s what made me itchy all over.

Andrew Huberman (52:58):

I think they’re just,

Rhonda Patrick (53:01):

like, I haven’t found a good krill oil supplement. I pretty much stay away from it. I mean, if you smell it, too, I mean, it’s just like, it just smells so bad. I mean, it’s just like, it just smells rancid. So, but the thing is, and I also published a paper on this back in 2019 or, yeah, something like that, about DHA in phospholipid form getting into the brain through a different mechanism than DHA in triglyceride form. And so it’s going through a transporter called the MFS-D2A transporter. And I think it’s very relevant for people with an ApoE4 allele.

Andrew Huberman (53:38):

So I kind of- People with an Alzheimer’s susceptible-

Rhonda Patrick (53:40):

Right, so like 25% of the population has an allele and a gene called ApoE4. And basically it’s ApoE, but the four is referred to as the bad kind of version of it. This is something in our bodies. It’s also in our brain. And if people have one of these versions, if they got one from their mom or their dad, they have a two-fold increased risk for Alzheimer’s disease. If they get two, which is much, it’s much more, it’s less common. I think it’s like 2% of the population or something has two alleles. But they have like a 10 or 11-fold increased risk of Alzheimer’s disease.


So there is a role for phospholipid form, DHA in the brain, but you also make phospholipid DHA inside your body. And you can do that by taking in more triglyceride form. So two grams like the magic, two grams or more is the magic number, I think. So kind of back to like the why for fish oil, and I personally think it is one of the most powerful anti-inflammatory things, dietary lifestyle, things that we can get easily, relatively easily, that is gonna powerfully modulate the way you think, the way you feel, and the way you age. And a variety of different types of studies kind of led me to that conclusion, a variety of observational studies. So there’s been lots of work by Dr. Bill Harris and his collaborators looking at what, it’s called the Omega-3 index. So this is actually the Omega-3 level in red blood cells. So red blood cells turn over about every 120 days. So it’s a long-term marker of Omega-3 status. This is very different from 99.9% of any study you see or any lab that you go to to get your Omega-3 levels tested. You’re getting your plasma phospholipid levels tested, which is kind of like, you can think of it as, what did I eat a couple of days before? Oh, I had fish. My Omega-3 levels are great, but did you eat fish like that every week? Or was it like you went out to dinner? So it’s not a great biomarker for long-term Omega-3 status.


It’s kind of like the fasting blood glucose levels versus the HbA1c, which is like a long-term marker, right, of your blood glucose level. So the Omega-3 index, he’s done a variety of studies, observational studies. So for people listening, these are studies that are obviously flawed because they’re not establishing causality. You’re looking at people’s lifestyles. But in the case of Bill Harris’s work, he’s measuring something. So he’s measuring the Omega-3 index, and he’s measuring the Omega-3 index in people and then looking at their mortality risk, for example, or their cardiovascular disease risk. And what he has found is that most, first of all, standard American diet has an Omega-3 index of 5%.


But Japan, by contrast, has an Omega-3 index of around 10 to 11%. Big difference there. And they also have about a five-year increased life expectancy compared to people in the U.S.

Andrew Huberman (56:51):

And that’s- Do you think that’s mainly due to their fish intake, seafood intake?

Rhonda Patrick (56:53):

So what he showed was, I think it’s a big part of it. I mean, you can’t always say it’s the only thing, but what he showed in his data was that in, and I think it was Framingham’s study, where he looked at the Omega-3 index in people that had a Omega-3 index of 4% or lower, so close to what the standard American is, but a little bit lower.


They had a five-year decreased life expectancy compared to people that had an 8% Omega-3 index. And so, big difference there, right? Five years life expectancy. Here’s the really interesting thing, Andrew. He also looked at smokers and their Omega-3 levels. And so he stratified it, right? And he found smokers that had no Omega-3 were like the worst of all. I mean, it was just like worst, right? We all know smoking is bad for us and will take years off our life expectancy. But smokers that had the high level, like smokers that were taking their fish oil or eating fish or whatever it was they were doing to get them up to 8%, they had the same life expectancy as non-smokers with the low Omega-3 index, right?

Andrew Huberman (57:60):

Wow, and that’s amazing. And it’s also amazing to me that people still smoke cigarettes, but I see a lot of people vaping. And I know a lot of people consume cannabis, right? Has there been any studies of specifically of vaping or people smoking marijuana? And all-cause mortality.

Rhonda Patrick (58:21):

I haven’t seen those.

Andrew Huberman (58:23):

I haven’t seen those. They’re not motivated enough to come in as research subjects. That was, again, a poor joke. It is hard to study people marijuana use unless I’m told by my colleagues that study this stuff, unless you offer people marijuana, in which case they’ll do it. But again, they’re actually not very good research subjects in all seriousness, because they are not very motivated or consistent and they forget their appointments. So that’s incredible. And you mentioned that the data on pollution related to the plant compounds earlier. So it’s almost like these things are, again, are acting in a reparative way.

Rhonda Patrick (58:60):

The Omega-3s are, I mean, they are resolving inflammation. They’re like blunting inflammation. They’re doing so many different, they affect so many different parts of the inflammatory pathway, which is, I think, it plays a huge role in the way we age, the way our brain ages, the way we feel, our mood, just our joints, all that. And so it’s amazing.

Andrew Huberman (59:25):

I love fish oil. I feel better when I take it. I try to eat some fatty fish a couple times a week. I do want to just touch on food sources for a moment. First of all, are there plants that are rich in Omega-3s? And second, I have some friends who are really into meat, and I like meat a lot. My dad’s Argentine, but I don’t eat very much of it. I try and eat high-quality meats in relatively limited amounts, but I do eat pretty often. But I’ve been told by these sources of questionable authority that if an animal grazes on really good grasses, for instance, that the meat can contain a lot of Omega-3s, which in principle makes sense based on this Omega-3 index, because you’re telling me that a lot of it, this Omega-3 is sequestered into the red blood cells. So if I’m eating high-quality grass-fed meat and the grasses had Omega-3s, do my steaks have Omega-3s or not?

Rhonda Patrick (01:00:22):

So there was a study published that compared conventional meat, so meat that animals are fed corn or soy or whatever.

Andrew Huberman (01:00:33):

Which is terrible for animals and people. As far as I can tell, I’m sure I’ll get some attacks, but that’s okay. I won’t read those comments. The, again, a joke, I read all the comments, but it seems to me that these animals have to get, either be taking fish oil or eat plants that are very rich in Omega-3s in order for the meat to actually contain sufficient Omega-3s.

Rhonda Patrick (01:00:58):

So the meat, comparing the conventional meat to the grass-fed or pasture-raised cows or cattle, there were higher levels of alpha-linolenic acid. And ALA, it can be converted into EPA and DHA. But the conversion is very inefficient and very dependent on a variety of factors, including genetics. Genetics, a huge regulator. Some people can do it much better. Others, you’re getting 5% of conversion to EPA. Estrogen is a major regulator of making that more efficient.


And it makes sense because pregnancy, when your estrogen just goes through the roof, I mean, these Omega-3 fatty acids play a very important role in brain development. So women are supposed to be converting any ALA they can into the longer chain Omega-3 fatty acids, right? So estrogen does affect that. But I would say plant sources, so if you’re looking for the ALA, plant sources would be walnuts, flax seeds. Those are probably the highest. But if a person is a vegan or a vegetarian, their best bet is to actually get a vegan. Their best bet is to actually get microalgae oil. And you can supplement with microalgae oil because microalgae, they do make the DHA.


And so that would be a better source for people that are vegetarian and vegan rather than doing the flax seed oil because that conversion inefficiency, the enzymes that convert ALA into EPA and DHA, again, it’s inefficient.

Andrew Huberman (01:02:42):

And then for people that eat fish, sardines, you said? Salmon. Salmon, and you have to eat the skin, as I understand.

Rhonda Patrick (01:02:50):

You don’t have to.

Andrew Huberman (01:02:51):

Okay. It’s good. It’s rich with omega-3.

Rhonda Patrick (01:02:54):

The oil, yeah. And the reason I say like, I think the best would be wild Alaskan salmon versus a farm-raised because a farm-raised, again, they’re feeding them, they’re feeding them corn. They’re feeding them like green and stuff. And then they give them astaxanthin. So astaxanthin is a carotenoid. It’s the carotenoid that’s in things like crayola crustaceans that make their red pigment.

Andrew Huberman (01:03:15):

Yeah, it’s also being used now as a supplement. And there’s a prescription form to try and rescue some age-related vision loss because of the role of the vitamin A pathway in photoreceptors.

Rhonda Patrick (01:03:28):

Yeah. Well, you know, actually the carotenoids themselves, so like luteinine, zeaxanthin, they’re really good at sequestering singlet oxygen, which is some damaging, right?

Andrew Huberman (01:03:37):

Yeah, as we age, because the retinal cells of the eye are so metabolically active, they accumulate a lot of reactive oxygen species and mitochondrial repair and limiting reactive oxygen species is a major theme of trying to rescue vision. I think that’s a whole other podcast and story. There’s some really interesting data now on the use of red light to try and trigger these pathways from Glenn. That’s my good friend of many years and amazing scientist, Glenn Jeffrey’s lab at a university college, London. We should talk about that at some point.

Rhonda Patrick (01:04:10):

If not today. I saw that study like 2020.

Andrew Huberman (01:04:12):

Now they have a second study. Oh, do they? No, it’s looking real. I mean, you know, they’re cautious. They’re appropriately British and cautious about it. You know, I always joke, if those studies had been done over here, everyone would already know about it. Glenn is a very conservative guy, but they’ve done this stuff now in pigs and rodent models, and now also two studies in humans. It’s looking pretty interesting. So sardines, but also anchovies. I mean, by the way, I hate all the food items that I’m describing. I can barely tolerate salmon. I don’t like fish at all. Actually, I like live fish. I had fish tanks when I was a kid. I just don’t. No, I find fish, unless it’s in sushi form, I find it absolutely repulsive. And I don’t know why. I probably have some mutation.

Rhonda Patrick (01:04:54):

So raw fish is actually higher in mercury than cooked?

Andrew Huberman (01:04:57):

Okay, well, that’s good. Now, I don’t really like sushi that much anyway. You’re giving me great reasons to not eat fish, but except I should eat these other fish sources or supplement more heavily.

Rhonda Patrick (01:05:07):

That’s the best message I’m getting. I eat sardines, like every day, my first meal almost is a can of sardines and an avocado with like- Avocado is good. Yeah, with a little bit of lemon and then some little hot sauce. Does avocado have omega-3s? Avocado is very good in monounsaturated fat. It’s not really high in polyunsaturated fat. Omega-3 really, I mean, it’s either the DHA and EPA that’s in the marine sources, fish, or it’s the plant ALA source, which is like the flaxseed or the walnuts.

Andrew Huberman (01:05:37):

So- It’s rough. I mean, all these companies now are making these plant-based products that taste like meat. My wish is that they would just make a fish that tastes like a steak.

Rhonda Patrick (01:05:49):

But that’s- The fish come out albino, the ones that they farm raise because they don’t eat any of the-

Andrew Huberman (01:05:54):

I’m joking. I don’t want a genetically modified fish that tastes like a steak. Although, you know, I love the taste of steak. The point here is that if one doesn’t see themselves regularly consuming these fish sources of omega-3s, it seems to me that the only way to really get them is from supplementation.

Rhonda Patrick (01:06:15):

And supplementation is a good way to get a high dose and to get back to your dose point. There was a couple of studies that basically, you know, I think there was some way they showed that people that are in the 4% omega-3 index range in order to get to the 8%, right, the five-year increased life expectancy if we’re comparing the two groups, was to supplement with at least two grams. It was about two grams a day. And I think it was a little bit less if it was triglyceride form, but I think two grams is a good, safe number. So most Americans that are not eating a lot of fish and they’re not supplementing are probably around a 4% to 5%. Probably around a 4% to 5% omega-3 index. And to get to the 8%, and I think that’s a good empirical way of thinking about it, right? Okay, well, I want to get to that 8%. By the way, I’m almost 16% omega-3 index.

Andrew Huberman (01:07:06):

Yeah, I was going to ask about testing. So where can somebody measure, where and how can somebody measure their omega-3 index? Which again, just to remind people, is essentially the percentage of omega-3s that you have in your blood with the caveat that the omega-3 index will be heavily biased by what you ate in the previous days.

Rhonda Patrick (01:07:27):

No? Not the omega-3 index. Okay.

Andrew Huberman (01:07:28):

So the omega-3- Sorry, I misunderstood. I thought you said in red blood cells. If I ate salmon two days ago, my omega-3 index is going to go up.

Rhonda Patrick (01:07:34):

No, that was plasma. I misunderstood. That’s okay. So most people are measuring, like if you look at a lot of studies, and honestly, Andrew, I think a lot of the reason for conflicting data is because people are measuring plasma omega-3 levels. Okay. The phospholipids. It’s in a phospholipid, right? So your phospholipids are carrying things. These are lipoproteins. They’re carrying things like omega-3 and triglycerides and stuff and shuttling them around. So the omega-3 index is actually in the red blood cells, and red blood cells take 120 days to turn over. So if you’re going to do a baseline test, if you want to know before supplementing what your level is, you have to wait 120 days before doing the second test after supplementing to know how much you went up, because that’s how long it takes for your red blood cell to turn over. So the omega-3 index, Bill Harris has a company that he co-founded. It’s called OmegaQuant, and they measure the omega-3 index. They have a variety of different index tests.


You can do like a basic one or a little more advanced. This is from a blood draw. It’s a little blood spot thing, yeah. And he uses money to funnel back into doing lipid research. He’s out there doing all sorts of interesting studies on omega-3s. It’s great. But the omega-3 index is great. I think that honestly more people and more researchers should be using it, because the conflicting data, it always comes down to what we’re measuring, the sensitivity of it. Are we even measuring anything? So you’re giving someone 500 milligrams of DHA, and you don’t see any effect. Well, did you measure what their levels were, and did you measure the omega-3 index? There’s all sorts of problems with randomized control trials, and I think that we need to, as scientists, we need to come together and make some progress. Let’s all talk to each other. Let’s figure things out. This test is out there. It should be used. It should be used not just by Bill’s group, but like everyone.

Andrew Huberman (01:09:34):

Yeah, well, and I’m learning so much from you, and I agree we need more collaboration. I’ve always enjoyed really fruitful collaborations in my lab at Stanford, and collaborating is just so much more fun. Online, there seems to be a bias more towards creating silos as opposed to bridges, but I appreciate that you bring up the need for more collaboration, and knowing which measures are best, and in this case, now I’ll thank you for the clarification. I understand this omega-3 index is going to be best. You mentioned you, so basically, when now when I look at you, I think you are 16% omega-3.

Rhonda Patrick (01:10:07):

And dolphins are 19%. I’m almost- Is that your goal? You’re trying to get there? It is. It is.

Andrew Huberman (01:10:12):

To do the interesting, actually, they should probably do something where you’re trying to achieve the omega-3 ratio of your favorite species. Now that we’ve covered a bit of how to get these things into one system, depending on what one eats, et cetera, and some of the better measurements, how is omega-3 and some of these other related lipids, how are they having these positive effects? In my mind, and this is incredibly elementary, but my understanding is that at some level, they’re making platelets more slippery. Is that true or not? I hope, I’m happy to be wrong. How is it possibly impacting my mood? Is it through the synthesis of membrane on neurons that allows neurons to release more transmitter, like serotonin and dopamine? What are some of the purported, reported, and known mechanisms?

Rhonda Patrick (01:11:04):

I think some of the most well-known mechanisms do have to do with the omega-3 fatty acids being very powerful regulators of the inflammatory process in some way, shape, or form, whether that has to do with resolvins that are produced, so from the metabolites of like DHA, for example, resolvins play a role in resolving inflammation. You want your inflammatory response to be activated when it’s supposed to be, but you want to resolve that inflammation and inflammatory response in a timely manner, right? And resolvins help do that, and so resolvins are one, and then there’s these specialized pro-mediating molecules, the SPMs, that also help resolve the inflammation.


Like you mentioned, the leukotrienes and prostaglandins, and these things are being affected by EPA, and they do affect platelets and platelet aggregation, and they do affect that whole pathway as well, and so there’s just, and there’s, I think there’s just so many different ways and inputs, and so when we talk about inflammation, honestly, it’s a big general term, but you’re talking about, when you’re talking about serotonin release at the level of neurons, we know that these inflammatory molecules cross the blood-brain barrier, and I just mentioned ago about injecting people with lipopolysaccharide and causing depressive symptoms.


It’s known that omega-3, actually specifically EPA, is able to help serotonin, inflammation inhibits the release of serotonin, and so EPA is actually able to blunt inflammatory responses along with DHA as well. DHA does that through resolvents and stuff, and this then helps more serotonin be released because you’re not having so much inflammation getting into the brain and affecting serotonin release. That’s one mechanism, and then another would be, well, DHA itself has been shown, it’s a very important fatty acid that makes up cell membranes, many cell membranes, including in our neurons, and as you very well know, Andrew, the structure and function of receptors, of transporters, these membrane-bound proteins on the surface of our cells, including neurons, are affected by the membrane fluidity, like how rigid and how fluid the cell membrane is, and DHA plays a role in that, and so, for example, in animal studies, if you make an animal deficient in DHA, their serotonin receptors, dopamine receptors, they’re affected because the structure of them is affected through the fluidity of the membrane, and so I think that’s another mechanism, and I’m talking sort of general because I’m not a neuroscientist.

Andrew Huberman (01:13:41):

No, but it makes perfect sense. I mean, we know, for instance, neuroplasticity, almost always, involves the recruitment of more receptors or an improvement in some feature of receptors to neurotransmitters, and they literally move laterally in the membrane, they kind of float around like little rafts. Sometimes they are, in fact, in lipid rafts, and so it makes perfect sense that these molecules like DHA, which are part of the structural fat of the neuron because, of course, the outsides of neurons are basically fat, not just the myelin that people have heard of, but the actual membranes, that getting that right, you wouldn’t want it as rigid as concrete, but you wouldn’t want it as soft as…


Need to come up with something here. What’s that gooey stuff that kids play with? It’s like that goo, anyway. There’s a, yeah, it’s disgusting, and it’s too soft to be a membrane for a neuron.

Rhonda Patrick (01:14:30):

That’s what we know. Someone put it in the comments

Andrew Huberman (01:14:32):

and tell me what that disgusting gooey stuff is. You don’t want your neurons to be that gooey, and yet you don’t want them to be like concrete either. It’s a balance. It’s a balance.

Rhonda Patrick (01:14:40):

It’s a balance. It’s a balance.

Andrew Huberman (01:14:44):

In mentioning DHA, I’m just going to, I realize I’m backtracking, but I want to make sure that we close all the hatches for people. We talked a lot about EPA, but are food sources of DHA that you find particularly attractive either by taste or by potency for DHA? What are just a few that we could throw out? Because I am aware that there are supplements where you can get a nice ratio of EPA to DHA, or you take them separately as you do, but if I want to make sure that I’m getting enough DHA, what do I need to be sure I’m eating on a regular basis?

Rhonda Patrick (01:15:15):

Well, the fish is packaging the DHA and EPA in the ratio. But I also do eat salmon roe, which is very salty, and it’s a really high source of the phosphatidylcholine DHA that we-

Andrew Huberman (01:15:30):

This is fish eggs. It is. Yeah. And actually- That I like for some reason. Oh, do you? Yeah, so I’m discovering something about myself. This was not meant to be nutritional psychotherapy, but you’re doing that for me anyway. I’m discovering that, yeah, I like eating embryonic fish. I just don’t like eating the actual fish. Okay, well- Okay, so fish eggs are okay.

Rhonda Patrick (01:15:51):

So caviar, basically. Caviar, yes. And that’s a good source of the phospholipid form. And I was consuming that a lot because I wanted to get the phospholipid form. So, and it’s actually really good. There’s been some animal studies and piglets and rodents as well showing that consuming phospholipid DHA during fetal brain development gets like 10 times more DHA in the brain. Again, it’s-

Andrew Huberman (01:16:15):

Makes sense based on fetal development. So do I need to buy Beluga caviar? Stuff can get pretty expensive at $200 a tin.

Rhonda Patrick (01:16:23):

I don’t think you need to, yeah. I think it’s a matter of preference and if you’re supplementing with your two to four grams of fish oil, I mean, you’re going to get phospholipid form anyway because your body’s going to make it.

Andrew Huberman (01:16:38):

Okay, I’ve seen some containers of what I assume to be quality fish eggs that are not at the caviar level that you can find in the better grocery stores that aren’t super expensive. I wouldn’t dip as low as to go eat, for instance, like fishing bait. Like when we were kids, we used to go fishing. You put the fish egg on the thing. That’s probably not good. Although it’s good enough for the fish, apparently. Okay, only half joking here, folks. I’m just trying to protect you from yourselves. Don’t get any crazy ideas about eating fishing bait. Okay, so that’s great to know. So we have these plant-based compounds. We have the omega-3s, so you PA DHA, and then you mentioned there’s a third category. What would you place in your third category of foods or supplement-based nutrients that our health, brain and or body health, can really benefit from?

Rhonda Patrick (01:17:27):

I mean, I think the most obvious would be vitamin D, which is actually, as you know, a steroid hormone that we produce when we’re in the sun. Depending on the time of year, we can make it in our skin, and depending on how much melanin we have on our skin or whether or not we’re wearing sunscreen or how old we are, there’s a sliding scale on how efficient that process is.

Andrew Huberman (01:17:49):

And as I understand, there’s an inverse relationship where the darker your skin is, naturally, the more vitamin D you need to consume. Is that right?

Rhonda Patrick (01:17:59):

Well, the darker your skin is, the harder it is. So there was a study out of the University of Chicago, this was several years ago, where they looked at African Americans and compared African Americans to Caucasians with light skin, fair skin, and how well they could make vitamin D from sun exposure and how long they had to be in the sun to make X amount, right? And it turns out that African Americans with darker pigmentation, which protects them from the burning rays of the sun, it’s a natural sunscreen, had to stay in the sun like six times as long as someone with none of that natural sunscreen. So I think the take home there is a lot of people with darker skin living in sub-Saharan Africa or people living in India with darker skin or in the Philippines, these equatorial regions where you tend to see darker skin because it’s protection from the burning rays of the sun. And adaptation. They are in the sun more. Right, yeah. And they’re getting more vitamin D, but people that maybe moved to the United States like Minnesota or in a place where UVB radiation isn’t getting to the atmosphere 12 months out of the year, it’s only getting there four months, for example. Or even living in our modern day society where people just don’t go outside anymore. I mean, we’re inside, our laptop’s in school, we’re at work, we’re in our cubicle, whatever. So supplementation does play a major role, not only for people with darker skin that aren’t outside all the time, but for everyone. 70% of the U.S. population has inadequate vitamin D levels. 70 of the whole U.S. So this is everyone. And so I think that insufficient levels defined as less than 30 nanograms per milliliter, and that’s sort of defined by the endocrine society looking at a lot of different aggregate studies and all-cause mortality, for example. There’s been a lot of different meta-analyses of all-cause mortality studies where vitamin D levels really seem to be ideal between 40 to 60 nanograms per milliliter.


And so in order to get to that level, if you are not outside all the time, live in Southern California where you’re always outside without sunscreen on, I always wear sunscreen because I’m trying to protect my skin from so many wrinkles and stuff, right? But also skin cancer is somewhat of an issue as well.


So basically the point is that vitamin D is a steroid hormone, meaning it actually binds to a receptor, and another receptor dimerizes with it, the retinoid receptor. And that complex goes into the nucleus of a cell where your DNA is, and it recognizes little sequences of DNA called vitamin D response elements. They’re called VDREs. They’re specific sequences of DNA that this complex, bound to the vitamin D receptor, goes inside and recognizes and turns on a whole host of genes, turns off a whole host of genes.


I mean, this is important stuff. Imagine 70% of the population having insufficient testosterone, right? It’s a steroid hormone.

Andrew Huberman (01:21:05):

We might be headed there, but probably not. No, I think that its names are very important, and I think that one of the issues is that vitamin D is called vitamin D. It’s not called DHEA or variant, blah, blah, blah. It doesn’t sound like a hormone. I also, I’m glad that you’re mentioning skin as the major kind of interface between the environment and vitamin D synthesis, because a lot of people think of skin as just a protective sheath around us or something to adorn ourselves with earrings or tattoos or whatever. But skin obviously serves those roles, but the skin is an endocrine organ. It has the capacity to make things that impact hormones and to make hormones. There’s this beautiful study out this last year where this took place over in Israel where they had people get outside for 20 or 30 minutes a day, three times a week, exposing a culturally acceptable, yet substantial amount of their skin during that time and saw big increases in testosterone and estrogen.


And this is through a keratinocyte-linked pathway involving P53. This was done in humans, but they did some knockout studies in parallel. And what this study told me or reminded me is that skin is an endocrine organ. So the idea that sun could trigger the activation of a production of a hormone is really interesting and makes total sense. So when vitamin D gets into cells and it’s binding to these VDR-E’s, what sorts of things are they triggering? So like for testosterone, we know it’s going to trigger protein synthesis, muscle growth, tendon strength, et cetera. With estrogen, it’s going to keep your neurons going, your joints feeling good. I always remind people that, by the way, because guys always seem to want to increase their testosterone and reduce their estrogen. Just remind people, if you reduce your estrogen, guys, your libido will plummet to near zero. Don’t crush your estrogen. It’ll also make you stupid.


If you’re not already stupid, it will make you stupid. So estrogen’s vitally important for males and females. When vitamin D gets into cells, what sorts of things is it stimulating?

Rhonda Patrick (01:23:12):

Okay, so first of all, it’s regulating more than 5% of the protein-encoded human genome. More than, and this was, I say more than because when I was looking at this data really in depth back in, starting in 2012 to 2014, it was that, and then it’s now grown. But one of the important things that you’ll find interesting that I published on back in 2014 was that I’d gone through this big published database where someone had published all these genes they found VDREs in. And basically I found that tryptophan hydroxylase one and tryptophan hydroxylase two was on there. And so then I started looking at the sequence and I was doing some in silico work. And it turns out that the VDREs and tryptophan hydroxylase two, so for people listening, tryptophan hydroxylase is an enzyme that converts tryptophan into serotonin. So tryptophan is what we, an amino acid that we get from our food. You convert tryptophan into serotonin in the gut, but you also do it in the brain. However, serotonin does not cross the blood-brain barrier. So tryptophan has to get into your brain and then you have to convert it to serotonin in your brain. Well, the enzyme that does that in your brain is called tryptophan hydroxylase two, and it’s activated by vitamin D.


The one in the gut is actually tryptophan hydroxylase one. Some of my published work hypothesized that it might actually be repressed by vitamin D because it has a sequence. The sequence itself, this 12-nucleotide sequence, it can determine to some degree whether it’s gonna be activated or turned off. And so I was able to kind of look at that and think, oh, maybe this and that. And so since then, there have been some groups that have confirmed more with in vivo and or in vitro studies. Mine was all in silico.


All that stuff. Anyways, so serotonin, a really important one. But most people, I mean, this is regulating our immune cell, immune system. It’s regulating our blood pressure, all that water retention. I mean, bone, of course, homeostasis. 5%, more than 5%. I mean, I can’t tell you so much.

Andrew Huberman (01:25:27):

I mean, and with 70% of the US population deficient, I’m beginning to think that this could be the linchpin in a number of really important issues. So supplementing vitamin D3 is what I normally, here is the, I do, I take, I think I end up taking 5,000 IUs, sometimes 10 IUs of vitamin D3 per day. Just done that for a long time and I’ve had my levels tested and they’re in range. But I have a family member, I’ll just mention this. I have a family member who was not feeling well, just kind of feeling off, a little low, had some digestive issues. This went on a long period of time.


Was taking, on my recommendation, 15,000 IUs of D3 and was still deficient in D3. Now takes, and I’m not suggesting anyone do this as a special case, perhaps, but no chronic illness that we’re aware of, needs to take 30,000 IUs per day in order to bring their D3 range just into normal.


Which is, to me, is striking because they eat quite well, they’re a healthy weight, et cetera, but it, and it’s made a tremendous difference in terms of their mood. Now, of course, this is correlative. Now they feel better, they’re doing it. Who knows? They’re probably also getting outside more. But I mean, I think people need to get tested. They need to get their D3 levels tested, but where and what is a good starting range for people to think about D3 supplementation and again, foods that can increase D3?

Rhonda Patrick (01:26:53):

So vitamin D3 is a good way to supplement with it. Their vitamin D2 would be a plant source. You often find it as fortified in like foods like milk, usually D2. There’s been a-

Andrew Huberman (01:27:04):

Does anyone still drink milk besides kids? Oh, here, it’s like, you can’t find cow’s milk.

Rhonda Patrick (01:27:09):

I mean, all the lattes that you’re getting. Soy milk, what’s the other one? They’re fortified in those as well.

Andrew Huberman (01:27:15):

Oh. Oh, they are.

Rhonda Patrick (01:27:17):

They are, yeah. They’re fortified in- I have a hard time finding cow’s milk. Almond milk and oat milk and all that stuff. Yeah, they’re in all that stuff. Vitamin D is naturally to some degree in fatty fish. Like, you know, like you think about cod liver oil, right? It’s like it has vitamin D, but it’s not, you’re not gonna correct a deficiency with eating fish for your vitamin D. Like, you’re either gonna correct it with sun exposure, being in the right area, having the right amount of sun, and being the right age, because as you get old, you become very inefficient at doing that, converting vitamin D, making vitamin D3 in your skin.

Andrew Huberman (01:27:52):

Well, that’s probably what was going on here, because this person is getting up in there.

Rhonda Patrick (01:27:55):

There’s a lot of single nucleotide polymorphisms. We talked about APOE4 previously, but there’s a variety of genes that people, very common, actually. In fact, I’ve had many people that have done that exact same thing. So measuring your vitamin D levels before and after supplementation is the only way you’re gonna figure that out, right? Very important. If you don’t measure it, you don’t know. You can’t know what you don’t measure. So there’s a variety of SNPs that basically make that conversion inefficient. And in fact, there have been a lot of these Mendelian randomization studies. So these are studies where people, scientists will look at common SNPs, people that have these common variations of a gene that’s a little more than 1% of the population. So it’s not a random mutation. It’s actually found in a sizable percent of the population.


And then they’ve looked at various outcomes. And a lot of times, they’ll look at genes that are also involved in some kind of lifestyle factor, so vitamin D and SNPs that basically make the conversion of either vitamin D precursor into D3 or in D3 into 25-hydroxy vitamin D or into the active steroid hormone, which is 125-hydroxy vitamin D. And there’s a variety of different SNPs that show people. So you’re not looking at vitamin D levels at all. You’re looking at just the SNPs. And you know if they have it, they have low vitamin D. So it’s really a way of doing a beautifully randomized controlled trial with an observational study because you’re not biased. Vitamin D levels are also associated with health. People that have higher vitamin D are either outside more, they’re more physically active, or they’re aware of their health and their supplementing, right? So you always have to worry about that when you’re doing an observational study. But when dealing with randomization, it’s beautiful for that reason where you now just, people randomly have these genes and it’s not like, there’s no health status. Like if you have the SNP, like your family member was healthy and all that, you know, they were healthy and yet they couldn’t get their D levels up, right? So these Mendelian randomization studies have found that people that can’t convert into the precursor, the 25-hydroxy vitamin D, which is usually what’s measured, it’s the most stable form of vitamin D in the body, they have a higher all-cause mortality if they can’t do it. So people that don’t have it have a lower all-cause mortality. They have a higher respiratory-related mortality. They have a higher cancer-related mortality.


So to me, now why did I get on this rant? Oh, because you’re a family member. So basically, they also are more likely to get multiple sclerosis. This has all been done with Mendelian randomization. And so it really does hammer home the importance of measuring your vitamin D levels and being very proactive about that. I mean, you can get it done anyway, your doctor will do it, you ask them to do it, you know? So supplementation-wise, typically, if you don’t have one of those SNPs, for the most part, taking 1,000 IUs of vitamin D will raise blood levels by around five nanograms per milliliter. So let’s say you’re deficient, you’re 20 nanograms per milliliter, and you wanna get to four.


You’re gonna need at least 4,000 IUs if you normally don’t have any of these SNPs that change your metabolism of vitamin D, right?

Andrew Huberman (01:31:12):

Does it matter when you take it relative to sun exposure, time of day, with or without food?

Rhonda Patrick (01:31:19):

I’ve seen some not so great preliminary evidence suggesting maybe time of day is important. I don’t think it really, like I can’t seem to find anything that really suggests, because for it to actually be converted into the hormone, I mean, it’s stored.

Andrew Huberman (01:31:37):

It’s bad. It’s like- The steroid hormones are slow acting.

Rhonda Patrick (01:31:39):

Yeah, it’s not like a media thing, right? So maybe we’ll get some new data that’s like otherwise, but I just don’t, yeah.

Andrew Huberman (01:31:46):

It simplifies the problem anyway. So for people who are going to be stubborn and not get their D levels tested, and simply say, oh, I’ll just take some D3. That was me, by the way, until I got tested. I threw 5,000 IUs into the mix and figured, well, it’s not gonna kill me. It’ll bring my vitamin D levels up. I didn’t realize that’s a bit of a coarse way to approach it, but I feel fine and I’m still breathing an ambulatory. So is that reasonable? 1,000 to 5,000 IUs for most people will be reasonably safe. Again, we’re not making, just assuming that people are gonna just jump to it without the blood test.

Rhonda Patrick (01:32:26):

Of course. I think that if we look at the literature, the scientific literature, it is extremely hard to get hypercalcemia, which would be the major concern with really high levels of vitamin D3 supplementation. I mean, we’re talking like hundreds of thousands of IU a day for a long time. So- Hundreds of thousands. Yes, yes. Now, the upper tolerable intake was set by the Medicine Institute to be 4,000. It was just like the safe, it was kind of like one of those things where it’s safe. I personally take 5,000 IUs a day as well and my levels really hover around 50 nanograms per mil and I do out. I don’t put sunscreen on like all the time. Like I do put it on my face and I wear a hat, but like some of my skin is being exposed. So I do make it from the sun as well. But-

Andrew Huberman (01:33:19):

I’m glad you brought up the fact that you keep arms exposed if you, because in these studies that I mentioned before, looking at sun exposure on skin and increases in other hormones, testosterone, estrogen mainly, it became clear from looking at those data that the amount of skin that you expose is important, which makes perfect sense once you hear that. But I think most people are thinking, oh, I’m out in the sun, but are you wearing shorts and a t-shirt or are you wearing a sweatshirt and it’s a hoodie or are you all covered up out in the sun? Well, that might be great for setting your circadian rhythm by way of a light to through the eyes because that’s the primary mechanism for that. But seems to me that the more of your body surface that you can safely and appropriately, please folks, appropriately exposed to the sun, the more vitamin D you’re going to create, right? So laying out on your back deck in shorts and a t-shirt with arms exposed and legs exposed is a very different stimulus than walking around in jeans and a sweatshirt, right? Okay, okay. Especially if you have sunscreen on your face. I know it almost seems like trivially simple, but I’m not sure that people are used to thinking about their skin as a interface to create these hormones.

Rhonda Patrick (01:34:30):

Yeah. So surface area matters. And by the way, there have been studies looking at people that are deficient in vitamin D. In this case, it was African Americans that were given a 4,000 IU a day vitamin D supplement to bring them back to sufficient levels. And this was a smaller study than I would like, but it reversed their epigenetic aging by three years because again, it’s a hormone. It’s regulating more than 5% of your protein-encoding human genome. There’s been studies looking at vitamin D receptor knockout mice. And I use this a lot in my presentations when I’m talking about vitamin D and longevity. But if you look at these animals, the vitamin D receptor, as I mentioned earlier, vitamin D binds to the receptor and then it complexes with the retinoid receptor and they go into the nucleus of the complex and you turn on and turn off jeans. Well, if you get rid of that receptor, which is what you can do in animal studies, you can sort of determine like what effects there’ll be with no vitamin D, right? What, how do you study no vitamin D? And so what was found was that these animals, and in fact, I don’t think it was a complete knockout or, you know, cause I think it might be embryonic lethal, but-

Andrew Huberman (01:35:44):

Some hypomorphism, which is basically geek speak for a gene is very, is vastly reduced in its function, number and function, number, people know what I mean, but isn’t eliminated completely.

Rhonda Patrick (01:35:57):

Right, well, these animals, if you look at them after the age of four months, I mean, the mice look like, I mean, they’re accelerated aging, they’re wrinkled, they have no hair, I mean, they just, I mean, their lifespan’s shorter, I mean, they just, you can look at this animal and not know anything about mice or work with them and be like, that animal looks like it’s, you know, of course, mice lifespans are only like two, two and a half years, but like 500 years old.

Andrew Huberman (01:36:22):

Right, it looks like it went to graduate school twice. Actually, graduate school is a lot of fun. I like to think I age backwards in graduate school, which is not true, I look at the photos, I definitely aged forward. You on the other hand look exactly the same way you did 10 years ago, I’m not saying that to flatter you, but it’s absolutely true, I mean, the data are the data, it’s remarkable, so I think it’s, I’m definitely gonna try and get my omega-3 percentage up there, I’m not gonna, you know, hinge it all on that, but clearly you’re doing a lot of things right. So if I’m taking vitamin D3, I still need to get out into the sun, correct?


Okay, I think a lot of people don’t know that, or at least I have family members that have been a little bit resistance, like I take my vitamin D, so I don’t need to get outside as much. I think people are really afraid of getting out into the sun because they’re worried about melanomas, and to be honest, I’m as scared of sunscreen as I am of melanoma, like that some of the things in sunscreen are really spooky, mainly the compound, and here, I’m not one of these, I drink tap water, listen folks, like people cringe with it, I drink tap water, I have the occasional croissant or donut, I’m not, you know, I’m 90%, 80% of the time I’m doing the right things the right way, I think, although I’m now gonna improve on them with this new knowledge, but I don’t like what I see in most sunscreens because if you look at these compounds, they cross the blood-brain barrier. I don’t want compounds crossing the blood-brain barrier.

Rhonda Patrick (01:37:46):

Titanium dioxide.

Andrew Huberman (01:37:47):

Dioxide, some of the triclosans that are also in these cleansers. I mean, once you know a little bit about neurons, folks, you realize that the neurons you got are basically the ones you got for your entire life.


You know, there’s a reason why there’s a blood-brain barrier, a blood ovary, and a blood testes barrier is because the genetic material resides in the testes, the ovaries, and the brain, those neurons don’t turn over. There are a few new neurons, but not that many unless you’re a mouse, frankly. So protecting those is very key, and a lot of the things in sunscreen are downright dangerous. So I think there are sunscreens that are safe, but it’s very hard to figure out which sunscreens are free of these compounds. I’m amazed that they’re still on the market, frankly.

Rhonda Patrick (01:38:28):

I’ve always geared towards the ones with the minerals that are like reflecting it. It is somewhat difficult to penetrate things all the way through the skin and get into the bloodstream, but I don’t know, maybe some of these compounds get in there easily. I have seen the evidence with some of those things.

Andrew Huberman (01:38:46):

There is some evidence they go transdermal, and they-

Rhonda Patrick (01:38:50):

And they get in? Okay, well, I know that some of them react with the sun, and while they do protect from the UVA and or B, they like form massive reactive oxygen species and carcinogen. I mean, it’s like the very thing you’re trying to protect yourself from might actually cause, we don’t know. I mean, it’s completely speculation, but there is, I think, some more and more evidence coming out with some of those compounds, and I can’t remember all of them off the top of my head, but a lot of high-end ones also have, it’s the chemical sunscreen ones, the chemical ones.

Andrew Huberman (01:39:23):

I’m proposing that we do a journal club. A journal club, folks, is where academics get together and read papers, and they get together, and they pick apart the papers. There’s a strong correlation between being an early graduate student and being the most critical, because once you’ve actually published some papers, you realize that most studies, people are doing their best within the context of what they can do, but it’d be great to do a journal club at some point about sunscreens, because I’d love to really figure out what’s in these compounds. I mean, people are using them like crazy, and I’m not one of these people who’s like, oh, I won’t use commercial toothpaste or anything like that. Like I said, I drink tap water, I use commercial toothpaste, whatever, but when it comes to sunscreen, it freaks me out, because some of these compounds do go transdermal, and some of them cross the blood-brain barrier, and I’d like to keep my neurons free of that stuff. Anyway, we’re speculating now. Wear a hat. Wear a hat.


But get out in the sun and get your D3 levels up. Okay, so we’ve talked about these plant-based compounds, the omega-3s and D3. Unless there’s something else that you just absolutely must throw into the mix, I probably will return us to the conversation that I opened up with, which is about cold and heat, which admittedly, I pulled us off that path, so I’d take full responsibility for that. But before I do that, I just want to offer you the opportunity. Is there anything that fit to supplement-based or food-based compounds that you think are especially useful for brain and our body?

Rhonda Patrick (01:40:52):

I do think magnesium is important in there as well. I mean, I think, again, about 40% of the U.S. population doesn’t get enough magnesium. It’s an essential mineral we’re supposed to be getting from our diet, and it’s- Involved in everything. It is. It’s also involved in vitamin D metabolism. And in fact, being deficient in magnesium may make it more difficult for you to actually make vitamin D hormone, so that 125-hydroxyvitamin D. So one of those other factors, again, talking, we talked about genetics, but there’s also magnesium status as well. Considering 40%, that’s a big number. Now, you know, magnesium’s also involved in making ATP, the energetic currency of our cells. They’re, you know, basically all of our cells need ATP to do anything, and it’s also involved in utilizing ATP as well as DNA repair enzymes. These are enzymes that are involved in repairing damage to our DNA. I personally think that magnesium insufficiency is a insidious type, causes an insidious type of damage daily that you can’t look in the mirror and see.


Like, when you’re deficient in vitamin C, you’re like, my gums are falling apart. I have scurvy, right? But like, you can’t see DNA damage. You can’t see it, but it’s happening. It’s happening right now in my body, and it’s happening in your body. It’s happening, normal metabolism is happening every day. But we repair that damage. We have repair enzymes in our body called DNA repair enzymes. They require magnesium. Magnesium is a cofactor for them. What that means is, you know, a cofactor means enzymes need it to function properly, and so without that cofactor, they’re not doing it properly. And the way I like to think about magnesium, it’s easy, because people go, what food should I eat? Naturally, that’s the next question. Well, magnesium is at the center of a chlorophyll molecule. Chlorophyll is what gives plants their green color. So dark, leafy greens are high in magnesium. It’s one of the, and basically, what does the 40% insufficiency in the U.S. tell us? People aren’t eating their greens. They’re not eating their greens. They’re eating their packaged food. They’re eating their processed food. Standard American diet isn’t really high in dark, leafy greens. So dark, leafy greens are how I like to get my magnesium. I think it comes along with all these other important, I mean, you get calcium in them, you get vitamin K1, you’re getting a lot of other micronutrients, and you’re getting other compounds that we don’t know about, and ones that we know about, like sulforaphane, right?

Andrew Huberman (01:43:19):

As with broccoli, do I need to eat the dark, leafy greens raw? And in this case, I’m a little more open to it because I actually like the taste of, dare I say, kale, and kale’s a dark, leafy green, right?

Rhonda Patrick (01:43:34):

It’s obviously- And it’s high in lutein and zeaxanthin as well.

Andrew Huberman (01:43:37):

Yeah, no, I’m going to try cremate, meaning I’m not colorblind, but I just want to make sure it falls under the strict category. Because every once in a while, I’m like, oh, I eat my vegetables. I like avocados. And people are reminding me avocados is not a vegetable. I love vegetables also. But so kale, what are some other examples?

Rhonda Patrick (01:43:50):

Kale, spinach, chard, like Swiss chard, rainbow chard, romaine lettuce.

Andrew Huberman (01:43:55):

Is the bitterness an important component to this?

Rhonda Patrick (01:43:57):

For magnesium, no, but for sulforaphane, sulforaphane, for cruciferous vegetables, that would be the brassica family. But your question about cooking them, so magnesium, it is bound to the food matrix, and it can be somewhat less bioavailable. So cooking it can somewhat release the magnesium, but it goes into the water too. So you have to either steam it or kind of get your water in.

Andrew Huberman (01:44:33):

And with it, yeah, I personally don’t worry about it.

Rhonda Patrick (01:44:35):

I just don’t worry. I think like, but I also like, I too supplement with magnesium. I do take around, so supplementation with magnesium,

Andrew Huberman (01:44:37):

I just don’t worry. I think like, but I also,

Rhonda Patrick (01:44:45):

I mean, we could go on and on. Let’s keep this short and sweet because we’re gonna get back to the other stuff. But it can cause GI distress at like high doses. I personally like to take around 130 or 135 milligrams. That way it’s not like a huge bolus to my gut.

Andrew Huberman (01:45:02):

I think it depends on the form of magnesium too.

Rhonda Patrick (01:45:04):

Yes, yeah. I mean, you can take like magnesium 3N8, for example, and it doesn’t affect the gut as much.

Andrew Huberman (01:45:13):

Magnesium citrate is what I take. Yeah, it’s a pretty potent gut stimulus. I mean, I feel like it’s a little bit harder to man.

Rhonda Patrick (01:45:22):

Well, I take 135 milligrams should be pretty good. And citrate actually, oh boy, do we want to go here?

Andrew Huberman (01:45:28):

Sure, I mean, it’s up to you and we don’t have to. Personally, I’ve been supplementing with magnesium for a long time, I use 3N8 and bisglycinate and malate for different reasons. So yes, I would love to go there if you’re willing.

Rhonda Patrick (01:45:46):

I would say malate would be the best. And that has to do with the short chain fatty acids being good for the gut and a lot of work done by a former colleague of mine and good friend, Mark Shiganaga, showing that the short chain fatty acid, citrate, malate, lactate, but specifically malate really and lactate are the other major ones that get into the gut epithelial cells and are an energy source for the mitochondria and the goblet cells. So anyways, whole other.

Andrew Huberman (01:46:12):

That’s okay. Yeah, I take malate because I was told that it would be helpful. First of all, it doesn’t make me sleepy like some of the other forms of magnesium, which act as a mild sedative for me. They do tap into the GABAergic pathway, neurotransmitter folks that in general, broad sweeping generalization here can have somewhat of a sedative quality, which is why I take magnesium three and eight and or bisglycinate before sleep, 30 to 60 minutes before sleep. Definitely enhances my transition time to sleep and the depth of sleep. No question in my experience. There’s some data that three and eight can be, can be neuroprotective. Although those are still, those studies are still ongoing. I’m getting the sense that maybe you’re a little more skeptical of that than I am.

Rhonda Patrick (01:46:58):

Yeah, no, I’ve seen the studies with the three and eight. I think like looking at the actual data from the one clinical study, there wasn’t statistical significance until all three of the pieces of data were pulled together. But that really could just be because their sample size was too small.

Andrew Huberman (01:47:15):

Right. Right. Yeah, I’m thinking that that paired with it, there’s some work. Yeah, the Guosong Liu’s work on, so in the, this is getting kind of into inside ball of neuroscience, the quality of the labs matters, folks. And that’s something that’s not accessible to people outside of fields. And Guosong Liu and some of the other folks at that time at MIT, I think very highly of their work. And so the animal studies are indeed just animal studies, but I was pretty impressed by what they did in those studies, very pioneering when you think about this being done 10, 12, 15 years ago. And then, yes, we need more human clinical data, but for me, I figured that given the safety profile of MAG3N8, given that it helps me sleep better and sleeping better is just better for everything, frankly, that’s why I take it. And bisglycinate and 3N8 seem to be somewhat interchangeable, but I don’t know of any reports that bisglycinate can be neuroprotective. But malate, I take during the daytime.


For me, and again, this is subjective, it has a tangible effect in improving the recovery time from exercise. So I don’t know that I’ve been sore from a workout since I started taking malate, and I used to get very sore from even kind of trivial workout. So I don’t know what’s going on there, but I keep taking it.

Rhonda Patrick (01:48:30):

Malate, again, the short chain fatty acid, and I mean, when you do intense exercise, you release endotoxin from your gut. I’m just going back to the interesting work is that the malate, being the short chain fatty acid, and Mark Suginaga showing, this is all in animal research, by the way, but I mean, it was like feeding these animals malate. I mean, it really protected the gut, endotoxin release, and it affected metabolic syndrome and all sorts of things. But I think malate’s awesome, and I always try to eat green apples. They’re really high in malic acid. Oh, good to know. And tart cherries. Tart cherries are really high in it as well. They also taste really good. But I was really interested in the magnesium 3N8 stuff. I take a supplement called Magnesium by Moon Juice, and it’s like a little powder. It’s got a little bit of monk fruit, but it tastes good. So I do it a little bit before bedtime as well, probably several more hours though, because I don’t like to drink tons and tons of fluids before I go to bed. And it has magnesium 3N8 and a variety of other versions of magnesium in it as well, and I really like it. But I thought the magnesium 3N8 stuff was super interesting. I would love to see more clinical data as well, but I think once we get it, it’ll probably be like, oh yeah, it’s getting into the brain and it’s awesome.

Andrew Huberman (01:49:42):

So, you know, why wait? Right, and along those lines, I once put out a post that said, you know, I feel like there are a number of different categories of health information consumers online and understanding which one you’re in for which topic can alleviate a lot of the strain and stress of finding the information. There’s some people that are perfectly comfortable with data from a mouse study. It’s like, if it’s done in mice, great, I’ll try it. Other people say, no, it has to be done in humans. You know, double-blind placebo-controlled studies, you know, randomized clinical trials, et cetera. Then other people are just saying, you know what, I don’t even care about any of that. Just tell me what you do. And then other people are saying, you know what, I don’t even care what you do. Just tell me what to do. And then there’s this other category, which are if it’s in pill form or powder form, they’ll take it. And so I think a lot of the battles of people picking apart people’s posts and things have to do with the fact that people don’t realize that people are showing up to the table in one or some combination of those stances. We know people that will try anything and we know people that won’t take anything. So the idea here is to create an array of possibilities for people, and I think the animal data are very impressive. We should have you back on.

Rhonda Patrick (01:50:51):

I take it with the hope of, because I feel like the animal data is very promising. And so I’m like, it probably is.

Andrew Huberman (01:50:57):

So why not? Well, and obviously you’re doing things right. So cold and heat converge on some common pathways related to what you called intermittent challenge, which I love. I think if intermittent fasting, cold, heat, exercise, I mean, maybe even intermittent sleep deprivation, I keep waiting for the intermittent sleep deprivation movement. I will say I pull a few all-nighters per year just for work demands and procrastination and deadlines and I’m the worst combination of academic, because I’m both a procrastinator and a perfectionist. So you end up pulling some all-nighters. The sleep I get the next night is pretty amazing. I must say it’s the sleep of gods, but I don’t recommend anyone use sleep deprivation for that. But I could imagine that we also evolved having some sleepless nights. So this idea of intermittent challenges is a really attractive one. And I want to make sure that we credit you with the phrase intermittent challenge.


No, credit. Okay, Dr. Mark Mattson gets credit.

Rhonda Patrick (01:51:55):

Who is published and he has used that. He used that phrase, okay, great. We’ll make sure. Just like Dr. David Sinclair, I love the xenohormesis. He was in one of his publications just so many years ago and I just love it. It’s brilliant, a brilliant term.

Andrew Huberman (01:52:07):

Mark Mattson gets credit for that. Those Harvard guys are pretty smart. You know, I mean, it’s a good school, I guess. Of course, it’s a good school. We will credit the appropriate people. Thank you for that clarification. So you’ve talked a lot about the use of deliberate, what I call deliberate cold exposure only to distinguish it from cold that you might just be accidentally exposed to. But it’s sort of obvious when we say cold exposure.


There are some amazing data on cold. The other day I saw a post from you and you’ve included this in talks before. I did not know this until I learned it from you. So credit to you. That even 20 seconds of immersion in, I think it was four degree- 49 degree Fahrenheit. 49 degree Fahrenheit. Okay, I was translating this. 49 degree Fahrenheit water. So cold water can lead to long lasting increases in epinephrine adrenaline. And I have to presume other neuromodulators and neurochemicals as well. What are some cold protocols that you find particularly interesting or attractive from the standpoint of, I don’t know, pick your favorite. Metabolism, neuro slash mood effects, brown fat stimulation, which of course weaves back to metabolism. You know, we could do an entire episode all about cold, but what I’d love to know is what sort of activity or stimulus do you think is a reasonable and particularly potent one to use in terms of cold?

Rhonda Patrick (01:53:37):

So today I did three minutes at 49 degrees Fahrenheit. I have a cold tub.

Andrew Huberman (01:53:42):

So you get in up to your neck?

Rhonda Patrick (01:53:43):

Well, I try. I keep floating up. And so I’m like, it’s like really hard. So like, I would say like maybe most of my shoulder, I mean, really I’m floating up. I was telling my husband, I was like, there’s too much water in here for me.

Andrew Huberman (01:53:58):

Or too much salt in there? Is it like the Dead Sea where you float on top?

Rhonda Patrick (01:54:02):

Is there salt in there? I don’t know. He takes care of all the stuff that, you know, it’s the plunge.

Andrew Huberman (01:54:07):

Yeah, and by the way, the podcast, Nor I Am, sponsored by Plunge, they did give me one. That thing is fantastic. Also because it circulates the water. It does. Which makes sure that you break up the thermal layer and it’s even colder.

Rhonda Patrick (01:54:18):

It is even colder. It sucks. Anyways, so look, I’ll be honest here. I wish I did more cold than I do. I do cold when I’m gonna go on a podcast. I definitely do cold when I’m gonna do a podcast, when I’m gonna give a talk, or when I’m anxious. I need to make it more of a ritual. I love doing the sauna.


Eat it. Unless it’s summertime. It’s a lot easier for me to get in the cold in the summertime. But what I do love about the cold is how I feel after. And I feel less anxious. I feel good. I feel more focused, which is why I usually do it before any type of public speaking or when I’m just anxious. I’ll just get in there. And so the 20 seconds at 49 degrees, I think it was 49 degrees Fahrenheit, was really a good number because time and temperature do, time or duration, I guess would be a better word, and temperature do matter. But you can do 20 seconds at a colder temperature, which is what I prefer. Or you can do a minute or longer at a warmer temperature. I think there was another study showing 59 degrees Fahrenheit at one hour. It was like two, three, four. But who wants to do one hour at 59?

Andrew Huberman (01:55:36):

Yeah, I’m familiar with that study. I love, so this really reveals just how absolutely nerdy I am and maybe why some times and relationships in my life were challenged. I love reading the methods sections of papers. So people can come at me with a number of things about papers, and I might miss something. Surely I miss certain things like anybody does. But the methods, I relish in reading the methods. And that paper’s really interesting because they had people sit in lawn chairs basically in swimming pools for an hour. And it was chilly. It wasn’t super cold. I mean, 60 is not, it’s not warm, but it’s not ice cold, obviously. But an hour is ridiculous at some level. But the increases in dopamine were massive and lasted hours. So it’s really, so the mood enhancing effects that you report are, they’re not, you’re not imagining that. Those are almost certainly a, the consequence of having slowly elevating, but significantly elevated dopamine that goes on for hours. That’s almost a dream-like profile for dopamine because most everything else, like an Adderall, a Ritalin, a cup of coffee, and a workout drink or a pre-workout drink or something is going to give you a big spike in adrenaline and dopamine and a big crap.


And somehow it creates this really nice contoured profile. So I, whatever you’re experiencing there is very nicely supported.

Rhonda Patrick (01:57:00):

Well, I need to get, I need to get doing it more. I’ve had a couple of scary experiences going from hot to cold where blood pressure changes, I think, where I basically went straight from a really hot jacuzzi. I was in there for like 30 minutes. I mean, I was doing heat stress. Jacuzzi, okay. Yeah, 104 degrees Fahrenheit. That’s toasty. And then, for 30 minutes. And then I went straight into, at the time, it was our pool and it was in like February. It was like winter time. And it was 50, it was in the 50s. It was cold. And I was in there and I was like listening to Simon Garfunkel. I was like trying to stay in a long time, get on my cold and I was trying to impress Dan because he like goes in there for like, he’ll stay in there for like 15 minutes.


I started to feel really like blinky, like low blood pressure or something. And I got scared. So I got out and then I couldn’t stand like I had vertigo or something. And I was so scared, I was so scared. And so, and I’ve had a couple of times too where I’m just going straight from the sauna to it, to the cold plunge, where I’m starting to feel, I’m like, ooh, I feel a little blood pressure change or something. And it makes sense. The sauna is causing vasodilation and the cold plunge, or cold exposure is causing vasoconstriction. And so it’s like a very, you know, just shock to my system. And so now I wait. Like I wait like a few minutes before going in. But I do need to kind of like make it more, the cold more routine. Because I talk all about the science. I’m familiar with all the science. And you know, the norepinephrine or noradrenaline, you know, it’s affecting brain and mood. And you know way more about that than I do. I know how I feel. And I know it’s a neurotransmitter. And you know, it is released, at least in rats they’ve shown, or was it mice? I think it might have been rats. But multiple studies showing in that it’s released from the cold in the brain.

Andrew Huberman (01:58:53):

And now in humans as well. So in that study, we can put a link to this. It’s published in 2000, European Journal of Physiology. That big dopamine increase. They also looked at epinephrine and cortisol. And saw some really. Yeah, so this has been done.

Rhonda Patrick (01:59:06):

They did brain. Oh, I didn’t. Oh, no, no, not yet. The plasma.

Andrew Huberman (01:59:10):

No, yeah, yeah, yeah, yeah. Very hard to measure dopamine directly from the brain unless you’re doing micro dialysis. No, unfortunately, their skulls were intact. Fortunately for them, unfortunately for the research community, their skulls were intact. So they couldn’t measure directly in the brain. But obviously there’s a correlate there.


You know, it’s a very real effect. I think that, but the advantage of not doing it too often is that you’re not cold adapted. Now it’s very hard for anyone to get truly cold adapted. Some people start to look forward to the cold. And what I think they’re looking forward to is the feeling afterward, that dopamine rush. But if you get cold adapted, then it certainly blunts some of the effect.

Rhonda Patrick (01:59:51):

But I want to be cold adapted because that means I have more mitochondria in my adipose tissue and perhaps even muscle, like that’s been shown.

Andrew Huberman (01:59:60):

So maybe there’s a good opportunity to, so cold and UCP1, if you could educate us on UCP1, I find this really interesting. And I learned about it from you, so.

Rhonda Patrick (02:00:08):

Yeah, well, so norepinephrine actually released in the plasma, it does act as a hormone.


Vasoconstriction’s one thing it does, but it also regulates a variety of molecular functions that have to do with adaption to cold. One happening to be, you know, shivering is a very inefficient way to produce heat, which is what your body’s trying to do when it’s exposed to cold. And your muscles are basically contracting and producing heat from that, but that’s just not very efficient. So the more eloquent way to do it, or elegant, I guess, way to do it, is to basically have your mitochondria produce tons and tons of heat. So the way it does this is by activating a gene called UCP1, uncoupling protein one, norepinephrine is upstream of that activating it. So what that does is essentially, so mitochondria are these little organelles inside of your cells that are responsible for producing energy. Usually that’s in the form of adenosine triphosphate, ATP, and that’s what lets everything function inside your body, from your neurotransmitter production to your heart beating, et cetera. However, you can uncouple your mitochondria. Basically, your mitochondria, they’re like a little battery, so they have, well, they have a double membrane, first of all, their structure, but they have a negative charge on the inside, and they have a positive charge on the inner membrane, so in between the outer membrane and the inside part. Like a neuron.


Like a neuron, yeah. So I guess it’s like a neuron. It’s like a battery, negative and positive. Well, basically, you can uncouple that charge, and so that positive charge, protons start leaking out of the mitochondria, and your mitochondria freak out, so this is called uncoupling it.


And they start to, it’s maximum respiration, as we call it. They try to make as much energy. They’re like, I gotta get that proton back, that gradient, the electrochemical gradient, and so they just go insane, and in this case, it’s uncoupled energy, so the energy they’re making is actually heat, not ATP, but heat is, but you’re essentially burning substrate, so who cares? You’re burning glucose, you’re burning lipids, you’re basically burning things and making heat, and so that’s what uncoupling does, and that is a much more efficient way of producing heat than shivering, so as you become more adapted, maybe the longer duration that you’ve stayed in the cold or the more times you’ve done it, you’ll no longer shiver anymore. You will start to then just do this uncoupling type of thermogenesis, as it’s called, and another type of adaptation that occurs is you actually produce more mitochondria in your adipose tissue, and that actually happens, also regulated by norepinephrine or noradrenaline through a protein called PGC1 alpha, and what that protein does is it makes more mitochondria in your adipose cells, so per adipose cell, you’re getting more mitochondria. It’s a beautiful way to basically make more heat when you’re, it’s one of those things where it’s like, your body’s going, okay, I’m gonna be exposed to this cold next time. How can I make sure I don’t die? Oh, I can have more mitochondria, and I’m gonna make more heat, and so you’re making more mitochondria in your adipose tissue, and this is often referred to as the browning of fat, and the reason for that is because if you look under a microscope at a lipid drop, basically a fat cell, not a lipid drop at adipocyte, you’ll find that it looks darker because there’s more mitochondria in there, so it’s referred to as browning fat, and so I don’t wanna get into the whole beige fat, brown, you know, there’s this whole, I’m sure you’ve had experts on that talk all about that, but-

Andrew Huberman (02:03:49):

No, not yet. I mean, I always think of white fat, beige fat, brown fat, and beige is kind of intermediate. White can be converted into beige, but-

Rhonda Patrick (02:03:55):

Right, and beige can take on thermogenic characteristics, essentially, and so you can activate beige fat so that it’s thermogenic in the sense that it’s burning glucose and or fatty acids and producing heat, so the more you expose yourself to cold, the more you can brown your fat, so to speak, and therefore you can tolerate the cold for longer periods, which people do notice, and you can then have the thermogenic qualities of having more brown adipose tissue or beige, activated beige adipose tissue, which is, you know, you’ll get a lot of naysayers out there saying, oh, brown fat doesn’t regulate metabolism at all, and the reality is there’s thousands of researchers trying to brown fat and thermogenic, like they’re trying to make it a pill because it does affect metabolism. It’s not the only thing. It’s certainly, if you’re obese and trying to lose weight, you’re not gonna do that just by doing cold exposure. You need to do dietary and exercise changes predominantly, but it does affect metabolism, and this has been shown in human studies, so it is an interesting, it’s another possible mechanism for affecting metabolism, and that’s in adipose tissue, but you also make more mitochondria and muscle tissue, and this is regulated not via norepinephrine, but it is still PGC1-alpha, interestingly. Not that anyone else really cares, but maybe you do, Andrew.

Andrew Huberman (02:05:27):

I’m eating this up.

Rhonda Patrick (02:05:29):

So PGC1-alpha is response to norepinephrine in adipose tissue to make more mitochondria, but in muscle tissue, it’s unclear what the regulator is. Cold exposure does it, so this was shown at least in a couple of studies I’ve seen where people that were exercising, I believe, or maybe it may have been men only that were exercising did some separate training and then did cold water immersion, something like 50 degrees Fahrenheit, 15 minutes, and PGC1-alpha, which is a biomarker for mitochondrial biogenesis, which is the generation of new mitochondria. By the way, that’s awesome. You want more mitochondria in your muscle. It’s associated with improved muscle mass, improved endurance. I mean, mitochondria are essentially either the making energy in your cell, and we don’t make more mitochondria normally. You have certain inputs, high-intensity interval training, exercise can do it.

Andrew Huberman (02:06:21):

You can actually make more mitochondria.

Rhonda Patrick (02:06:23):

Yes, yeah, and that’s been shown in people.

Andrew Huberman (02:06:26):

Weight training or just high-intensity interval training?

Rhonda Patrick (02:06:28):

I haven’t seen weight training. I’ve seen it in high-intensity interval training, endurance training, but that doesn’t mean that it hasn’t been shown. I just haven’t seen it or that it hasn’t been looked at.

Andrew Huberman (02:06:39):

It’s good to know I’m always looking for reasons to finally do more HIIT-type high-intensity interval training work. I do weight training, and I do low-intensity cardio.

Rhonda Patrick (02:06:48):

There was a brilliant study by, at the time he was a postdoc, Matthew Robinson, and he’s now gone on to start his own lab at the University of Oregon Health Science Center. I can’t remember that. And he did this study where both young and older people, they had this whole high-intensity protocol, which I can’t remember what it was, but their protocol for X amount of time, I’m sure it was at least a month, they then measured biomarkers of mitochondrial biogenesis in their muscle tissue, and the amount of mitochondrial biogenesis in old people specifically, it happened in both young and old from HIIT, from the high-intensity interval training, I mean, it was like enormous, at least 50%, I think. So I mean, it was just like, whoa. And so why would you want that? Well, mitochondria, your cells are turning over, you make new cells, you replace old ones with your mitochondria. You don’t really do that for the most part. You can, mitochondrial biogenesis does happen, but you have to stimulate it to happen. And what happens with your mitochondria is they essentially are bobbing around inside of your cells, and then they fuse with other mitochondria, exchange all their content, mitochondrial DNA, and then fizz back apart, and that’s how they kind of stay young-ish. But as you age, you keep doing that with the same pool of mitochondria, and you’re gonna get a bunch of old mitochondria mixing old stuff together, right? So why wouldn’t you wanna bring up new, healthy, young mitochondria into that pool, right? So in my mind, when I hear mitochondrial biogenesis, I’m like, aging. That’s the first thing I think of. So anyways, cold exposure does that.

Andrew Huberman (02:08:30):

Other things as well, so. You know, and please, thank you for offering to somehow filter the level of detail, but I assure you that listeners of this podcast are familiar with getting, drinking from the fire hose of mechanism, and that was really helpful. And again, this is just one example of maybe four or five other things that you’ve said, at least, that are gonna inspire me to change my behaviors. I’m gonna start doing some high intensity interval training. Dr. Andy Galpin was on this podcast recently, and he told me that the subtle zone two cardio and the weight training is great, but that I really should be doing some max heart rate work per week. You know, going into max heart rate for 90 seconds and resting and repeating that, maybe even mild repeats. I’m just curious as a brief aside before we talk about heat, what sort of cardiovascular or other types of training do you do? Do you do HIIT? I imagine you are doing high intensity interval training. If you could just give us a sense of the contour of your week as it relates to exercise, and because you’ve been very gracious in sharing some of what you do for supplements and food, what about exercise?

Rhonda Patrick (02:09:35):

So I, it all depends on my week, of course, and what I’ve got going on with my son and my work schedule, but I typically, I do a lot of high intensity interval Tabatas on a stationary cycle. I use Peloton because I just, like that instructor there, like telling me what to do and then me competing with everyone else. I’m like, nah, you know?

Andrew Huberman (02:09:55):

So it works for me. You’re revealing something about your psychology. This is good. We just learned about, so this podcast is actually just a decoy for psychological assessment of the guests. No, I’m kidding. But so now we know you’re competitive. Good? Yeah. That explains a lot of how you got through graduate school and then do what you do. So you’re getting on the Peloton, and what does it look like for someone who’s not familiar with Peloton? I know what they are, but I’ve never been on one. You are peddling against the instructor for how many seconds?

Rhonda Patrick (02:10:22):

So you’re, there’s a bunch of people that are online either doing the class with you at the same time or have all time doing it. So you can kind of toggle on what you want and like, you can try to compete against.

Andrew Huberman (02:10:33):

Oh, so it’s really competitive. Oh yeah.

Rhonda Patrick (02:10:35):

Okay. And the instructor is just there to like whip you, like, you know, make you, there’s a part of, the brilliance with Peloton is like, I used to do rush, what’s called rush cycle. And I used to go in, it’s basically you go in and group cycle and have an instructor there and you do all this high intensity interval training stuff. And I loved it because there was a competitive aspect to it that had me working harder than I would work if it was just me in the room, like without an instructor or anyone there. And it was just like, I’m at a gym, any gym, and I’m just on a stationary cycle listening to a podcast, doing something, which is fine if that’s your group, right?


But there is something about that group setting that kind of holds you accountable too, right? And the Peloton made it somehow virtual. It was amazing. And I remember being back at rush cycle, this is before a pandemic, and people talking about Peloton in my class and I’m like, oh, that’s ridiculous. Why would I do that? Like, that’s never gonna work. I need to like be here. And then the pandemic hit and I was like all over the Peloton and it works for me really well.


So I tend to do that at least three times a week. Sometimes I do it more, like I’ll do four. And I do a 10 minute, just 10, because it’s efficient and I push my ass. I push myself really hard. That’s the Tabata. It’s 20 seconds on, 10 seconds off, and it’s 10 minutes.

Andrew Huberman (02:11:55):

And on means you’re pedaling like your life depends.

Rhonda Patrick (02:11:57):

You’re maxing it. And there’s a lot of resistance in the pedals? Well, so you basically, there’s a part where you’re, I always do resistance. I’m like the power, I do the power for, there’s a part where you’re sitting cycling and you’re trying to go really fast, but I always crank the resistance up. I always go above what they give me. And then there’s a part where you’re standing and then you really crank the resistance up, which I really do. And like you feel it in your glutes. It’s like going up a hill. Yeah, exactly. And so they like break it up and most of the time you’ll have like those two parts. And I love the efficiency of it. You just, you get it done. And people sometimes hear me go 10 minutes or really you think you work. I’m like, look, like you max, you do max, you and Tabata for 10 minutes. And it’s like, it’s intense.

Andrew Huberman (02:12:36):

Yeah, most people can’t sprint for the gate of an airplane they’re about to miss carrying a backpack. So if you think about, if I think about that, and then I’ve just described myself, sprinting through the airport and going, all right, Andy Galpin, I got my 90 seconds max heart rate in for you carrying this thing. But 20 seconds on, 10 seconds off, repeating that over and over for 10 minutes. So by the time you’re done, you’re cooked.

Rhonda Patrick (02:13:00):

And then I, because I’m competitive during the recovery that they give you at the minute, at the end, I’m pushing it max.

Andrew Huberman (02:13:06):

Great, great. So three times a week.

Rhonda Patrick (02:13:09):

Yeah, three times a week. And then I always have my sauna on preheating up. It takes about an hour and a half and I get it to about 189 degrees Fahrenheit. I hop right in the sauna after my Peloton.

Andrew Huberman (02:13:20):

So the elevated heart rate continues, is that the rationale?

Rhonda Patrick (02:13:23):

Yeah, I mean, I literally like down a bunch of water and then I get in and then I like either read a science paper, prepare for a presentation or a podcast or I hash over things in my mind. And it’s interesting because something about getting in the sauna, I think the stress, the heat stress of it, I used to, so I started doing the sauna in 2009 in graduate school. Okay.

Andrew Huberman (02:13:49):

And I. You’re an early adopter.

Rhonda Patrick (02:13:50):

I started doing it every day. I lived across the street. I lived in a studio apartment with Dan. We lived in this like small studio apartment, the smallest apartment you could ever imagine. And it was across the street from a YMCA because I was poor in graduate school, very poor, very poor, I mean. So, you know.

Andrew Huberman (02:14:05):

I recall, I recall being, I lived in my lab. Wow. But then again, I lived in my lab as a postdoc and as a, I admit, I lived in my lab with my bulldog as a faculty member for other reasons. But I get it. When you’re a graduate student, you’re poor.

Rhonda Patrick (02:14:21):

Basically. Yes. And so I used to, I used to go to the sauna before going into the lab. And I would, and I would, I started noticing that I was all of a sudden able to handle stress better. Like the stress of my six month setback because of failed experiment, which is crushing.


On top of the pressure from your, my advisor and my own pressure because I’m very competitive with myself and I put a lot of pressure on myself. So I was having a hard time, I mean, I was very stressed out in graduate school and the sauna started to really noticeably affect my anxiety and my ability to handle stress. And I was like, what is going on here? So I started looking into the literature and, you know, started getting interested in the effects on the brain. And in fact, at the time I had a friend who was not actually experimentally but theoretically looking into the, the opioid system. And basically, so when you get in the sauna, you release a lot of endorphins. Endorphins are the feel good, feel good opioids that, you know, make you feel good. But you also release something called dynorphin. And dynorphin is an endogenous opioid that binds to a receptor called the Kappa opioid receptor, which dynorphin is responsible for that dysphoric feeling when you’re in the sauna and you’re hot and when you’re running, doing exercise, and you’re like, you feel uncomfortable.


Well, I think that’s dynorphin, I’m speaking absolutely.

Andrew Huberman (02:15:52):

No, I think it is. I mean, there’s evidence in alcoholics that some of the symptoms of withdrawal that they experience are related to dynorphin. And dynorphin is known to negatively impact the dopamine receptor system. So basically, it’s the feel like garbage pathway.

Rhonda Patrick (02:16:09):

Right, you feel like garbage. And so you think that that would not be good, but this is where my friend that comes in, he was looking at the effects of treating morphine or heroin addiction and people that are using those drugs. They basically, the endorphins or the morphine or heroin, they bind to a receptor in the brain called the Mu opioid receptor. And as they take these drugs, that Mu opioid receptor becomes down-regulated, and so you need more and more of the drug to feel as good as you did, right? Well, endorphins also bind to that receptor. And he was looking into some of the other drugs that are like salvinorum or something, salvia it’s called. It binds to the opioid receptor. It also makes you kind of feel uncomfortable.


Anyways, he had put some studies in front of me that showed basically binding of either dynorphin or whatever ligand to the Kappa opioid receptor basically sensitizes the Mu opioid receptor to the feel-good endorphins and also changes. I think it also up-regulates it or something. So basically, there’s a lasting effect of feeling good. So the endorphins that you release later from hugging someone or a joke you’re laughing at or whatever, you feel it for longer, right? And so anyways, with respect to the sauna, it’s a big sort of hypothesis of mine. I did kind of publish that part of my hypothesis in a review article, but I do wish more people would kind of look into that. That’d be amazing. But what I was getting at, I think, was I would use the sauna to memorize things. This is way back in the day, and I still do it. And I wanted to talk to you about this because you’re a neuroscientist, that there’s something about being in the sauna. And I don’t know if it has to do with the stress response. Like when you have an emotional trigger, like you remember things better, right?

Andrew Huberman (02:18:10):

I mean- Absolutely. There is a clear and known explanation for mechanism for this.

Rhonda Patrick (02:18:16):

So in the sauna, I mean, you also release norepinephrine, just like you do in the cold. There’s a lot of overlap. I mean, it is a stressor, but I use it to remember things. Like I’m going through something. I want to go through a presentation or a talk or a podcast or whatever. And I go in that sauna, and I mean, you should try it, like if you haven’t already. I don’t know if you-

Andrew Huberman (02:18:37):

I have a sauna in a cold plunge now, and I haven’t tried preparing. I read books in the sauna in the evening. It’s a time I insist on having my phone out of there, mostly because I, initially because I thought I’d cook the phone, but also just to get some separation from the phone and screens in the evening. So I read books. The only challenge sometimes is you’re dripping sweat onto the books, but I’m willing to forego a few pages of a book. The idea that being in this semi-stressful environment would aid in the learning and retention of information is really well substantiated by this beautiful work by a guy named James McGaugh. I don’t know if his lab’s still active, but he was at UC Irvine for a while, and then I think at University of Arizona as well. They have a great memory group at both places, very strong in learning and memory, both places.


And he was the one that really defined this kind of inverted U-shaped function for the relationship between adrenaline and memory. Basically, if you’re too relaxed and not stressed enough, you’re not gonna remember any information. At peak levels of stress, you actually are a memory machine, at least within the context of whatever it is you’re trying to learn. So what you’re describing very well matches with that.


And then of course it tapers off as you really increase adrenaline to the point where people are starting to lose autonomic function where they’re just, they’re panicking basically, but obviously you’re keeping it in range. The other thing that I’d like to ask you about is in the sauna, of course, there’s vasodilation, and perfusion of blood to the brain is a wonderful way to enhance cognition. There’s even some really nice data showing that during inhales, as opposed to exhales, people are better at learning information.


Believe it or not, during the inhale, you’re taking in and absorbing and remembering more than during exhales. And these are beautiful studies done in humans, of course. So I can imagine that vasodilation, getting more perfusion of blood to the brain, plus a little bit of stress, or maybe a lot of stress from the epinephrine, and yet it’s, and then of course, there’s going to be the, I don’t want to call it placebo, but there’s going to be the context, the conditioned place context of it. Like if we had a good experience remembering something in the sauna once, we tend to, the positive association effect of that location is real. Just like if people go to a new city and they get robbed, like if you go to Cincinnati, I’ve never been to Cincinnati, but you get robbed in Cincinnati, your purse gets taken or your wallet gets taken. You kind of hate Cincinnati as a tourist, but that could happen in any number of different cities, right? The opposite is also true. So if something good happens someplace, so I’m imagining that it’s a combination of those effects, but I’ll start, it would be very hard to do this in the cold. I feel like the cold is a very potent, I think it takes you too far down that curve, the McGaw curve.

Rhonda Patrick (02:21:14):

I have to sing songs or something when I’m in there.

Andrew Huberman (02:21:15):

Distract yourself. Oh yeah, I sing songs. But afterward, you’re very efficient at learning.

Rhonda Patrick (02:21:19):

After I am, and with respect to the sauna, the vasodilation does occur, so there’s a lot of overlap between moderate intensity aerobic exercise and heat stress. And as you can imagine, when you’re exercising, you’re elevating your core body temperature, you’re sweating. And when you’re actually in the sauna, blood does get redistributed to the skin to facilitate sweating. But much like exercise, blood flow in general is improved to the brain, to the muscles, everywhere. So I think generally speaking that, and there’s studies showing that sauna use is associated with a much lower risk of dementia and Alzheimer’s disease. Like people that use it four to seven times a week have greater than 60% reduction in dementia and Alzheimer’s disease risk compared to once.

Andrew Huberman (02:22:04):

Oh, sorry, I didn’t mean to cut you off. You said people who use it, I apologize, but maybe you tell us again, people who use it four to seven times per week have?

Rhonda Patrick (02:22:14):

They have a greater than 60% reduction in dementia risk and Alzheimer’s disease risk compared to people that use it only one time a week. People that use it two to three times a week have something like a little greater than 20% reduction in risk. There’s a dose dependent effect on dementia risk and Alzheimer’s disease risk. It also has a profound, like there’s a big link between the cardiovascular system and the brain, obviously blood flow, big one, right, you need to get blood to your brain. But cardiovascular mortality, so mortality from cardiovascular disease, if people use, or actually this was men, if men use a sauna four to seven times a week, it’s a 50% reduction in cardiovascular related mortality compared to one time a week. Again, dose dependent manner two to three times a week is something like 24% lower death from cardiovascular disease.


Cardiovascular disease, there’s also lower, you know, sudden cardiac death, it’s like a heart attack. That’s like 60 something, greater than 60% lower if men use it four to seven times a week versus once. Again, a dose dependent thing. And the thing that’s so profound there also to me, again, looking at the methods, when I look at the data, and this is all work from Dr. Jari Laukonen. He’s in the University of Eastern Finland and just one of the world experts on sauna use, especially with respect to cardiovascular health. What some of his data has also shown is that if you look at the duration, the time spent in the sauna, so a lot of the, so I mentioned the temperature I do is about, I do like 189 degrees Fahrenheit. Typically I go in there, I’m pretty heat adapted. And so the more you do, the more you do the sauna or any sort of heat stress, whether it’s a hot tub or jacuzzi, you become adapted. You basically start to sweat at a lower core body temperature to cool yourself down. All these sort of physiological changes start to happen earlier. And so I stay in for like 30 minutes. So I stay in a long time. That’s a lot. You have to listen to your body. Most of the studies that I just talked about were from the duration, the time spent in the sauna when I said 50% reduction in cardiovascular disease related death.


What was shown was that men that were in the sauna were only 11 minutes. Even if they used it four to seven times a week, that reduction was only like 8% instead of 50. It had to be greater than 19 minutes. So like 20 minutes is the sweet spot at about 174 degrees Fahrenheit.


And so, and most of the saunas in Finland, by the way, they’re humid, so they put hot water, not hot, they put water on hot rocks to create steam. And so it’s usually between 10 to 20% humidity in the Finnish sauna. So those studies were, I would say, most of the time you’re gonna find that their humidity is also elevated. But to me, the dose-dependent nature of it and the duration, knowing, like, you know, to me that’s a very strong data that this is more causal than some corollary thing because that’s always the problem with observational studies, including these, which they corrected for a whole host of factors like cholesterol, you know, exercise, just everything, everything under the sun. I mean, they corrected for those. And on top of that, you have the dose-dependent nature of the duration, the time spent in the sauna, and the frequency.


So to me, it’s like, something’s going on here. Plus there’s been studies, intervention studies where it’s like, you know, comparing directly head-to-head moderate intensity aerobic exercise on a stationary cycle to 20 minutes in a sauna. They’re physiologically the same things happen.


So heart rate elevates while you’re doing the activity. Blood pressure increases while you’re doing the activity. But then after heart rate decreases, resting heart rate decreases below baseline, blood pressure is improved, so it decreases below baseline. This is happening the same in moderate intensity cycling versus sauna. So again, the sauna, like, this heat stress, there’s something about it that really mimics this moderate intensity aerobic exercise, which is really great for people that can’t go for a run, that can’t even get on a bike.


So, you know, disabled people, granted there are some safety concerns, they’re pretty mild, but they do exist. So people that had a recent heart attack or have some rare kind of heart disease or problem, drinking alcohol, never do that. Elderly people prone to low blood pressure always talk to a physician before doing the sauna. It is stressful. Pregnant women, oh yeah, I definitely avoided saunas when I was pregnant.


But it is, I think it’s very relevant for disabled people and also people that are sedentary, have been sedentary most of their life. Like, my mother, I’ve been able to get her in the sauna because she’s not, I mean, I did get her on the Peloton once, but it’s really much easier. She feels like it’s a spa treatment and it’s like she can listen to her music in there and like, I care about her health, but she’s mostly been a sedentary person. And so I find it much easier to convince her to get in the sauna than to get on Peloton.


Ideally, you do both. The question would be, well, I exercise, I run, I do my high intensity interval training, why do I need to get in the sauna? And the reality is, and so I published all this in a review in the experimental gerontology last year, I guess, late last year. And basically, cardio-respiratory fitness, which is a marker of, it’s a marker of health. Cardio-respiratory fitness is improved in people that do exercise and sauna compared to exercise alone or sauna alone. So for those healthy, fit people out there already exercising, there’s a synergistic effect by also adding a sauna into that routine. And to me, that’s great, and there’s so many beneficial things happening with the heat stress in addition to like mimicking aerobic exercise. There’s the heat shock proteins that we talked about earlier and those, it kind of brings me back to my early days of science when I was at the Salk Institute for Biological Studies doing research on little nematode worms that we, or someone else, injected amyloid beta 42, the peptide, the 42 amino acid peptide that is involved in amyloid plaques found in the brain correlated with Alzheimer’s disease and other brain disorders. We injected those into the muscle tissue of worms.


And basically, these worms become paralyzed with age because the aggregated proteins, these proteins aggregate. Well, heat shock proteins, one of the main things they do is they basically make sure the proteins inside of your cells maintain their proper three-dimensional structure and are folded right. And so they don’t, they’re not prone to aggregating and forming these plaques in your arteries and also in the brain. And there’s, back to my worm studies I was doing, I would elevate heat shock proteins in those worms and it would totally correct the problem where they would no longer become paralyzed. They’d move around like they were young. So many animal studies have been done looking at Alzheimer’s disease, you know, like a human-like Alzheimer’s disease in a rodent and heat shock proteins protecting from it. So heat shock proteins are robustly activated in humans. This has been shown to even 50% higher over baseline levels after just 30 minutes at 163 degrees Fahrenheit in the sauna. So, and they stay activated at least in rodents for 48 hours at least. So having these heat shock proteins around, making sure they’re properly taking care of our proteins so they’re not aggregating in our brains and in our plaques could be another potential way that saunas protecting from Alzheimer’s disease and other cardiovascular health as well as longevity. So, you know, there’s people that have SNPs in heat shock protein factor 70 that if they have one of them, so they got one from their parents where they have more active heat shock protein 70, they live on average one year longer than people that don’t have that SNP. And if they have two versions, they got one from their mom and one from their dad, they live on average two years longer than people that don’t have that SNP. So it’s also been associated with human longevity as well as in lower organisms. So you can heat shock a worm or a fly and they live 15% longer.


This is work done by Gordon Lithgow at the Buck Institute years and years ago. So anyways, I guess what I was getting at was the heat shock proteins are part of that stress response pathway that we talked about earlier. And, you know, they’re also activated by cold as well. Cold shock does activate heat shock proteins, not as robust. Sulfuraphane activates them. Again, it’s one of the reasons I think we should get all of these things because they are more robust inputs. You know, their input activating mechanisms are more robust for different ones. So there is crosstalk. There is, you know, I mean, I guess it’d be more accurate to say there’s overlap.


But, you know, it’s also like you wanna get the most robust from all of them, right? I do. So, I mean, that’s why I wanna do the sauna and exercise and eat my broccoli sprouts and all that stuff.

Andrew Huberman (02:31:31):

It’s super interesting. A couple of questions came up for me. One is, you mentioned these SNPs, these nucleotide repeats, basically genes that some people have, more of or less of, than others that can predict longevity in some sense. Is that the FOXO3 pathway?

Rhonda Patrick (02:31:51):

That’s one that can, yeah. I mean, FOXO3 is, in fact, if you go back to the worm studies I was talking about, that was like one of the first things when you see it with your own eyes, you can take these worms that you basically decrease their insulin signaling pathway and their IGF-1. Worms have what are called homologous genes, so they have a lot of similarities to humans. They have an insulin-like receptor, they have an IGF-1-like receptor, and they make something like FOXO3, which we have. And basically, if you decrease that insulin signaling pathway their FOXO3 is always active in those worms, and they live like 100% longer. And not only do they live longer, I mean, they are like a very young worm. I mean, they are like, you look at this thing and you’re like, this looks like the worm that was just born like hours ago. What’s going on? This thing’s at the end of its life.


Now, as a side note, the thing that always got me on this was, by the way, this was discovered by Cynthia Kenyon, and this was like back in the 90s. And honestly, I’m not sure that anything has been as exciting in the worm world since then, but I thought, I mean, it was a really big finding. The only caveat there is that the worms go through this dour, it’s called a dour stage when this happens, when you decrease their insulin signaling and stuff. And they like go into this like metabolic stasis, like they’re not eating as much or moving. And so it’s like, okay, well, they live 100% longer, but like they go into this weird state.

Andrew Huberman (02:33:16):

I know people like this, some in the longevity community, they know who they are, but they’ll get the last laugh because I’ll be dead, well-fed, but dead, and they’ll still be going. So in terms of the many data on sauna, and I also just want to acknowledge these Finnish groups that did this work is really pioneering, right? And you think 20 years ago, long before social media or any of this, and they’re up there, I should say, measuring cortisol and growth hormone and all this stuff in people getting into sauna, very, very interesting. So 20 minutes seems like the threshold at 170 degrees Fahrenheit.


More times per week seems to be better than fewer when in terms of all-cause mortality, cardiovascular risk, according to what I just learned.

Rhonda Patrick (02:34:06):

Four would be a good, I think, minimum effective dose.

Andrew Huberman (02:34:09):

Four times a week, and you combine it with the cold. I’ve also seen a protocol where, it’s a very extreme protocol, I don’t recommend this to people right off the bat, where they had human subjects get into the sauna for 30 minutes, get out for five, 30 minutes, get out for five, 30 minutes, for a total of two hours of exposure. But that was what led to these massive 16-fold increases in growth hormone.


I actually have a, and they had to do it very seldom. So it sounds like these protocols you’re describing, 20 minutes done four times per week, far more reasonable for most people to access. But I know people are probably desperate to know what if they don’t have a sauna? A sauna is kind of a unique item. So I have a couple of questions. Can people use hot baths?


With the appropriate warning, of course, that without getting into description of the mechanics and the underlying biology, it’s pretty obvious that the testes, if they get too warm, you’ll kill sperm. That’s the reason why the testes are housed in a structure called the scrotum that can move around. So just to be, you know, here we are, biologists, just talking about realities here. So if you’re trying to conceive children or keep your sperm healthy, guys should probably stay out of warm, hot baths.

Rhonda Patrick (02:35:21):

For at least six months, that’s been shown. Six months. So sperm motility goes down and sperm production goes down, but that is completely corrected if they stay out of the sauna for six months. So six months later, it’s back to normal.

Andrew Huberman (02:35:36):

Great. That’s very useful information, I’m sure, to a number of people out there. So if people don’t have access to a sauna, and we get this about cold, too. You always say, what about cold showers? And I always say, well, the studies have mainly been done on immersion, because it’s hard to keep things controlled in cold showers. It just doesn’t make for a very good experiment, because you get a bigger person, less of them is under the shower. And so it doesn’t make for a good experiment. So it’s not as good as immersion. But with heat, I could imagine that a hot bath would work almost as well.

Rhonda Patrick (02:36:06):

Yeah, so there’s been some studies looking at, for example, activation of heat shock proteins, also brain drive neurotrophic factor increases with heat stress. And so the hot bath at around 104 degrees Fahrenheit, which is typically what studies will use for temperature, which is actually cooler than when I crank my bath hot. It’s so hot.

Andrew Huberman (02:36:24):

You’re very heat adapted. I’m very heat adapted, yeah.

Rhonda Patrick (02:36:27):

And it’s 20 minutes from the shoulders down. And that is a very robust activation in heat shock proteins and in brain drive neurotrophic factor. And then heat shock proteins are also protecting against muscle atrophy. So that’s also having to do with the protein structure and the muscle tissue as well. And this has been studies in animal data as well as some recent human data as well. It was local hyperthermia or local heat treatment, but essentially it showed that it protected.


I mean, it was like, there was a study where they were looking at muscle disuse and it was something like the local heat treatment prevented almost 40% of the muscle atrophy from disuse. So like, and it’s funny, because I used to use this on when I was injured and stuff.


I would go in the sauna because I didn’t know at the time because I was a graduate student, but I knew just from experiments that I’m not losing as much muscle. I feel better. At the time, I was reading all about the growth hormone and stuff back then. But, and I knew about heat shock proteins. So I kind of knew, but that data wasn’t around yet. And so now we have the data. And I’ve always felt like I wasn’t losing my muscle like I should have been when I was doing the sauna. And I was doing it literally seven days a week. It was like hardcore.

Andrew Huberman (02:37:42):

This is also during graduate school?

Rhonda Patrick (02:37:44):

Yeah, now I’m doing the sauna, like a bare, bare minimum. I do three, but I try to do four because of the, it all depends on my schedule. I also like to do long runs. I really, it’s like long being like three miles, not like Cam Hanes that’s too long. But I really, for me, and we were talking about this earlier like off camera that the runs for me are for my brain.


And I get this mind wandering effect where I daydream and I think about things. I work through problems. I get creative. I come up with ideas and this is all happening on the runs. And so I just, I miss my runs if I don’t do them. And I miss it because of the brain effects I get from it. And when I exercise, it’s funny because I’m a female and you think that I’d be exercising to stay fit and in shape and care about my figure. But when I exercise, literally what I’m thinking about is my brain and I’m like, this is the best longevity drug there is. This is it right here, Rhonda. Like you’re always wondering, you’re always wanting to know, you’re wanting to do the best. Like if you don’t exercise, you’re missing that essential dose. And so that for me is the motivation, the dopamine seeking thing I’m looking for. Admittedly, I do not do enough strength training and I have to do it, have to, have to, have to.


I’m like, I’m just, I’m so after the endurance and the hit. And I really need to add that in because muscle mass is also extremely important for aging as well. So that’s my fault.

Andrew Huberman (02:39:15):

Well, the brain effects are really interesting. I also run. I try and get one longer run per week and a few other runs and I do it without a phone. I don’t listen to podcasts. I occasionally will listen to music, but I really try not to. I also find that my mind solves problems. I feel like it washes out the cobwebs, so to speak. Some of the most brilliant and prolific neuroscientists that I know who’ve had very long careers, Eric Kandel, Nobel prize winner at Columbia comes to mind for all his work on memory, used to swim a mile a day. And now I think swims half a mile a day, but he’s in his late 90s and he’s still sharp, which is incredible. And his lab has done some work showing that any load bearing exercise repeated. So endurance work, unlike the Peloton or cycling, that’s really load bearing, although you’re cycling really hard with the resistance, but causes the release of osteocalcin from the bones, which acts in an endocrine way, sort of like a hormone can actually travel to the hippocampus and at least in these animal studies, induce the proliferation of neurons, growth of synapses, BDNF, a number of downstream things, which kind of makes sense. If we were to put a just so evolutionary story on this, a body that’s active can signal to the brain that the body still needs cognition. An inactive body in some ways is depriving the brain of any signal of what the body is doing, right? This is obviously I’m making this up as conjecture, but we know in various ocean animals that they’ll swim around for some period of their life and then they’ll have a completely stationary portion of their life. And basically the brain degenerates. You don’t need much of a nervous system if you’re not moving. So I think there’s really something there and also just letting your ideas and mind drift. I love that you, and I appreciate that you shared your protocols because I think right now we’re in an interesting time in public health information history where people are just kind of getting bombarded with cold is good, heat is gold, cold is good, heat is good, excuse me, I misspoke. There are all these micronutrients and of course macronutrients are important too.


And today you’ve really enriched us with the description of the underlying mechanisms and the logic behind them, but also sharing what you do is really informative because I think people need a jumping off place. And obviously they need to start someplace and getting heat adapted, et cetera, it takes time. But I really appreciate that you’re willing to share your protocols and that you do the things that you teach and educate people about. As a final question, because I have to ask, red light sauna or no red light sauna? I’ve been a little bit vocal about my feelings that none of the red light saunas I’ve ever been in got hot enough and it was frustrating. So I feel like it’s neither here nor there. However, I do acknowledge that red light and low-level light therapies are now known to do a number of interesting things. There was a Nobel Prize in 1908 for phototherapy for lupus. So it’s not like a new thing, the idea that red light and light could do things positive for our biology. But do you have a red light in your sauna? Do you think it’s useful? And I mention this because this is the number one question I get about sauna, red light or no red light or some intermediate answer?

Rhonda Patrick (02:42:30):

What’s the answer? So I don’t have an infrared sauna, but I do have, like I have a sauna that has lights. It makes red light, but I don’t think it’s the red light that you’re talking about. It’s not activating it at a specific wavelength, which is.

Andrew Huberman (02:42:43):

It’s usually so that the range that seems to be helpful and I have, I confess, I use a red light panel for other things is 670 nanometer out to about 720 nanometer. So it looks like red and very dim light, dim red and bright red. And the idea is that red light can travel, the photon and energy is such that it can travel down through the deep layers of the dermis of the skin.

Rhonda Patrick (02:43:11):

I don’t have a red light in my sauna. I don’t know if it’s essential or not. I don’t think so. Based on all the studies I’ve talked about, I think that would be as, is the potential effect on mitochondria is interesting. I do think there’s a lack of really good solid evidence in humans, but that might only be because it’s just not studied enough and that’s usually the case. So perhaps, like there’s the Juve, right? The Juve, they have those red light panels.

Andrew Huberman (02:43:43):

Juve and Cozy are the two ones I know, K-O-Z-E and Juve. They’re, as far as I know, I’m probably going to insult both companies at the same time, but I’d rather insult them both at the same time than just compliment one or insult one. Both of them seem excellent for getting the appropriate wavelengths of red light and I do not have a relationship to either.

Rhonda Patrick (02:44:00):

Yeah, well, I personally think that the sauna in and of itself, it’s about the heat stress. And typically the question I get is infrared sauna or regular sauna and there are some differences as well. Infrared saunas, maybe the infrared saunas are the ones that have the red light that you’re talking about. Infrared saunas only get up to around 140 degrees Fahrenheit, so as I mentioned, the studies were about 174 degrees Fahrenheit. And so you really have to stay in a longer period of time. However, there have been some studies coming out of Japan. They use infrared sauna, they have this whole protocol, it’s called Wayon Therapy and they get people in infrared saunas and then they wrap them in a towel and they stay warm for X amount. So the whole protocol ends up being like an hour long, but again, it’s 140 degrees Fahrenheit, so it’s an infrared sauna and it’s been shown to improve a variety of coronary heart disease and heart-related conditions, like there have been some improvements. So obviously there’s evidence that infrared saunas can be beneficial for cardiovascular health. I do, I’ve used infrared saunas many times at my in-laws, they have infrared sauna and I have to crank that thing up for a while until it’s maxed. And then I have to sit in there for an hour at least. I do sweat a lot and that’s another thing we didn’t talk about, you do sweat some heavy metals and some heavy metals are excreted predominantly through sweat and others through urine. So for example, cadmium, there’s like 125-fold increase in cadmium excretion from sweat when you get in the sauna. Also lead is something like 17-fold excretions higher. Another one is aluminum, it’s about four-fold higher. So infrared, you do sweat a lot too and that’s because the main difference is that you’re heating your body up through thermal radiation versus the ambient air, like a standard sauna is a heater and the heater’s heating up the air and that’s how you’re heating yourself up. So it is a little bit of a different mechanism. I prefer regular saunas, most of the data out there is from the heat stress itself, like your heart rate’s elevating when you’re in there, you’re feeling hot, you’re getting that cardiovascular, I mean that’s what you’re feeling when you’re in a hot sauna and that for me takes a really long time in the infrared sauna to get at the very end. But I do think there are some benefits from infrared and they are more affordable, they’re less of a fire hazard, but again, hot baths are I think a good alternative modality for heat stress compared to like a regular sauna.

Andrew Huberman (02:46:33):

Great, that’s a really helpful answer. Like I said, I use the red light but not in the sauna and thank you for reminding us of that 174 degree Fahrenheit threshold that was mainly used in all these studies. So we covered a lot of territory but I just want to thank you again, it was extremely thorough and extremely informative.


I’d now have my notes are always look a little bit like they were drawn out by a macaque monkey who has no knowledge of the English language but I can decipher this to tell you that there are at least 10 additions to my current protocols that I’m going to add and I’ll have lots of questions. So I apologize in advance for that but on behalf of the listeners and just directly from me, thank you so much for your time, I learned a ton.

Rhonda Patrick (02:47:21):

My pleasure, thanks for having on. It was really awesome conversation so I enjoyed it a lot. Let’s do it again. Totally.

Andrew Huberman (02:47:28):

Great, thank you for joining me for my discussion with Dr. Rhonda Patrick.


I hope you found it as interesting and as actionable as I did. Once again, if you’d like to learn more about Dr. Patrick’s work, sign up for her newsletter and to listen to her excellent podcast, go to You’ll find links to the newsletter as well as the podcast there or you can go direct to the podcast by going to foundmyfitness on YouTube, foundmyfitness on Apple or foundmyfitness on Spotify. And once again, the newsletter is slash newsletter. If you’re enjoying and or learning from the Huberman Lab Podcast, please subscribe to our YouTube channel. That’s a terrific zero cost way to support us. In addition, please subscribe to the podcast on both Spotify and Apple and on Apple, you have the opportunity to leave us up to a five-star review.


If you have suggestions of topics or guests or feedback of any kind, please put that in the comment section on our YouTube page. In addition, please check out the sponsors mentioned at the beginning of today’s podcast. That’s the best way to support this podcast. As also mentioned at the beginning of the episode, we are now partnered with Momentous Supplements. So if you go to slash Huberman, you’ll find what we firmly believe to be the highest quality supplements available in the specific dosages that match the peer reviewed science and recommendations made on various episodes of the Huberman Lab Podcast.


You will also find specific protocols of how much to take and when, what time of day, what time of night, et cetera. And you will also find behavioral tools that can synergize with those supplements. Many of you will also be pleased to learn that Momentous Supplements, of course, ships within the United States, but also international. If you’re not already following us on Instagram and Twitter, please do so. It’s Huberman Lab on both Instagram and Twitter. There, I teach science and science-based tools, some of which overlap with the content of the Huberman Lab Podcast, but much of which is distinct from the content of the Huberman Lab Podcast. Thank you once again for joining me for my discussion with Dr. Rhonda Patrick. And as always, thank you for your interest in science.


People Mentioned

Episode Info

My guest is Rhonda Patrick, Ph.D. She earned her doctoral degree in biomedical science from St. Jude Children’s Research Hospital at the University of Tennessee Health Science Center and has become one of the leading public health educators on the brain and general health, aging, cancer, and nutrition. We discuss the four major categories of micronutrients that regulate cellular and organ stress and antioxidants, inflammation, hormone regulation, immune system, and longevity. Dr. Patrick provides actionable protocols for obtaining key micronutrients from food and/or supplement-based sources. Additionally, Dr. Patrick outlines protocols for deliberate cold and deliberate heat exposure to benefit metabolism, cardiorespiratory fitness, mental health, and lifespan. 

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For the full show notes, visit


(00:00:00) Dr. Rhonda Patrick – Micronutrients, Cold & Heat Exposure 

(00:03:12) Momentous Supplements

(00:05:30) Sponsors

(00:09:42) Stress Response Pathways, Hormesis

(00:16:38) Plants, Polyphenols, Sulforaphane

(00:21:12) Tools 1: Sulforaphane - Broccoli Sprouts, Broccoli, Mustard Seed 

(00:23:50) Tool 2: Moringa & Nrf2 Antioxidant Response

(00:25:25) Sulforaphane: Antioxidants (Glutathione) & Air Pollution (Benzene Elimination) 

(00:27:10) Plants & Stress Response Pathways, Intermittent Challenges 

(00:29:35) Traumatic Brain Injury, Sulforaphane, Nrf2 

(00:35:08) Tools 3: Omega-3 Fatty Acids (ALA, EPA & DHA), Fish Oil, Oxidation 

(00:48:40) EPA Omega-3s & Depression 

(00:52:02) Krill Oil vs. Fish Oil Supplements? 

(00:54:23) Benefits of Omega-3 Fatty Acids, Omega-3 Index & Life Expectancy 

(00:59:24) Tool 4: Food Sources of EPA Omega-3s 

(01:06:07) Omega-3 Supplementation, Omega-3 Index Testing

(01:10:22) Benefits of Omega-3s 

(01:14:40) Tool 5: Food Sources of DHA Omega-3s

(01:17:07) Vitamin D & Sun Skin Exposure 

(01:22:18) Role of Vitamin D, Gene Regulation 

(01:25:30) Tool 6: Vitamin D Testing & Vitamin D3 Supplementation 

(01:33:15) Tool 7: Skin Surface Area & Sun Exposure, Vitamin D 

(01:34:23) Vitamin D & Longevity

(01:36:46) Sun Exposure & Sunscreen

(01:40:30) Role of Magnesium, Magnesium Sources, Dark Leafy Green Vegetables

(01:44:50) Tool 8: Magnesium Supplements: Citrate, Threonate, Malate, Bisglycinate 

(01:50:57) Tool 9: Deliberate Cold Exposure Protocol & Mood/Anxiety

(01:59:22) Tool 10: Cold Exposure, Mitochondria UCP1 & Heat Generation

(02:02:30) Tool 11: Cold & Fat ‘Browning’, PGC-1alpha, Metabolism

(02:05:08) Cold Exposure & High-Intensity Interval Training (HIIT), PGC-1alpha, Muscle 

(02:08:04) Tools 12: Exercise, HIIT, Tabata & Sauna 

(02:13:30) Tool 13: Sauna, Endorphins/Dynorphins, Mood 

(02:17:45) Tool 14: Mild Stress, Adrenaline & Memory

(02:19:53) Sauna, Vasodilation & Alzheimer’s and Dementia Risk 

(02:25:30) Sauna Benefits, Cardiorespiratory Fitness, Heat Shock Proteins (HSPs) 

(02:31:29) Insulin signaling, FOXO3 & Longevity 

(02:33:22) Tools 16: Sauna Protocols, Hot Baths & Fertility 

(02:37:41) Tool 17: Exercise & Longevity, Osteocalcin 

(02:41:37) Tools 18: Red Light Sauna? Infrared Sauna? Sauna & Sweating of Heavy Metals

(02:47:20) FoundMyFitness Podcast, Zero-Cost Support, YouTube Feedback, Spotify & Apple Reviews, Sponsors, Momentous Supplements, Huberman Lab on Instagram & Twitter

Title Card Photo Credit: Mike Blabac


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