where we discuss science and science-based tools for everyday life. [Upbeat music] I’m Andrew Huberman, and I’m a professor of neurobiology and ophthalmology at Stanford School of Medicine. 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.
Before we begin today, I just want to acknowledge that if you’re watching this on YouTube, yes, I have a bandage on the left side of my face.
I was trying to cook something for Costello and me, and I burned myself. It was a cooking accident. I’m fine, no need to dwell on it. We can move on, but I just wanted to let you know that everybody’s going to be okay. He got a great meal, and I got a burn and a great meal.
Today’s episode is brought to us by Four Sigmatic. Four Sigmatic is a wellness company that makes mushroom coffee. For those of you who haven’t heard of mushroom coffee before, I just want to make it clear: these are not psychedelic mushrooms, and no, the coffee does not taste like mushrooms at all. It tastes amazing, and it tastes like coffee. I started using Four Sigmatic coffee a few years ago, and then we actually stocked it in my lab.
We still stock it in my lab because it tastes really good, and it also happens to have two types of mushrooms in it that I particularly like because of their supplement and medicinal qualities. Those two are lion’s mane mushroom, which has been shown in several research studies to have a mild anxiolytic (meaning anti-anxiety) effect and mood-elevating effect. Those are from research studies done independently as well. It also has Chaga mushroom. Chaga mushroom has been shown to increase growth factors that impact the nervous system, like nerve growth factor.
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Today’s episode is also brought to us by Theragun. Theragun is a handheld percussive therapy device that releases deep muscle tension. I was introduced to Theragun on a dive expedition for my laboratory a few years ago. On that expedition, we were working very hard.
We were diving all day. We were carrying pelican cases with equipment. We were carrying tanks. Very sore, very tired by the end of the day, as was everybody else. Someone brought along a Theragun, and pretty soon that thing was getting passed around and became the most coveted device on board because it really works to relieve the soreness and deep muscle tension that accumulates with physical work, exercise, or even just sitting too long throughout the day.
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This month on the “Huberman Lab Podcast,” we’re talking all about hormones, these incredible chemicals that can impact our mood, our behavior, our feelings of optimism or pessimism. The amazing thing about hormones is that hormones impact all those things, but all those things—how we feel and what we do and what we think—also can impact our hormones. And so it’s a really fascinating area of biology that impacts every single one of us every day, both in wakefulness and in sleep and throughout the lifespan.
Today, we’re going to be talking about hormone optimization, and we’re mainly going to be focusing on estrogen and testosterone and their derivatives. Last episode of the “Huberman Lab Podcast,” we talked about sexual development. That is how the chromosomes, the gonads, and hormones impact what we call sexual development leading all the way up to puberty. Today, we’re mainly going to talk about processes that happen from puberty onward. Although we might talk a little bit about development as well, so today we’re going to talk a lot about basic biology, but we’re going to weave in a lot of practical tools along the way for how to optimize these incredibly powerful things that we call hormones.
Before we dive into our discussion about hormone optimization, I want to raise what I think is a very important point that at least I hadn’t heard of until recently, which is the concept of salutogenesis. Many of us are familiar with the concept of pathogenesis—the idea that there are all these scary diseases like dementia and heart disease and stroke, and all these things that await us if we don’t take good care of ourselves, and that might await us even if we do. That’s the pathogenic model. Salutogenesis is something I learned about from one of my Stanford Medicine colleagues, which is a different orientation toward health and well-being, where you’re taking on particular behaviors. You’re taking on a particular stance towards nutrition and exercise, supplementation, etc.
in order to promote well-being above where you would be if you were not doing those behaviors. Now, if you think about it, these two things—salutogenesis and the pathogenic model—are really two sides of the same coin. But I’ll just give an example of how this might affect you in a real way. If you like exercise because it feels good, great, but many people exercise or eat well, for that matter, in order to avoid heart disease or to avoid dementia, to avoid negative changes in body composition. And while that’s powerful and certainly is the case that exercise will help you move away from all those things, the salutogenesis model differs in that it involves a mindset and an orientation towards doing those things in order to feel good, in order to enhance your level of energy, in order to improve endocrine function and metabolic function.
So it’s really part of the pathogenic model, and yet salutogenesis is really more of a mindset toward why you would do these particular behaviors. And really, the most powerful mindset is going to be one where you are thinking about the pathogenic model—doing things so that you don’t end up sick, etc., and to move away from sickness—as well as the salutogenic model, where you’re doing things in order to move towards health and well-being. We think of health and wellness nowadays or the wellness community or wellness practices, and in many ways, that is the essence of the salutogenic model. But I found it very interesting to know that within the field of allopathic medicine, these two models exist.
But we don’t hear about the salutogenic model quite as often, so it’s just something to keep in mind, especially because of some of the mindset effects that were discussed in previous episodes. I’m not going to go into these in detail again right now, but if you might recall from the episode on food and mood, we talked about some of these incredible studies that were done by Alia Crum’s group at Stanford and others showing that if you tell people that the behavior that they’re about to do—in this case, it was people cleaning up hotel rooms because that was their job—if you tell them that it’s good for them, then you see much greater positive health effects than if they aren’t aware of that information that it’s good for them. So we should really be thinking about not just moving away from disease and negative things, but also why certain things are good for us, because it’s well-established now from really good scientific studies that keeping in mind the positive effects of things can really have an outsized effect on well-being right down to the level of our physiology.
So, let’s talk about hormone optimization. Today, we’re going to talk about hormone optimization in reference to estrogen and testosterone and their derivatives.
Now, estrogen and testosterone and their derivatives are what we call sex steroids. Now, the sex steroids immediately call to mind sex for obvious reasons and steroids, meaning anabolic steroids, but I just want to emphasize that estrogen and testosterone are present in everybody. It’s their ratios that determine their effects, and so today we’re going to talk about how you can optimize their ratios depending on your particular life goals because the ratio of estrogen and testosterone in every individual has a profound influence on feelings of well-being, feelings of optimism, feelings of anxiety or lack of anxiety, on reproduction, on sexual behavior independent of reproduction. They are profoundly powerful molecules, and we all make these molecules to some degree or another, but there are also important behavioral tools, supplementation tools, as well as prescription drugs that can impact the ratios of testosterone and estrogen in really powerful ways, so we’re going to cover all of that. I want to emphasize that when you hear sex steroids or steroid hormones, most people think about anabolic steroids, and of course, anabolic steroids are derivatives of testosterone or testosterone itself, and they are heavily used and abused in the sports community as well as outside the sports community.
But there, of course, are many steroids that are not anabolic steroids that are also abused in sports. Today, we’re not talking about drugs in sports, but I think that it carries such a heavy weight when people hear the word steroids, they think about anabolic steroids. So, while today’s discussion will certainly be relevant to physical performance—in fact, we’re going to talk about how specific types of exercise, particular patterns of cold exposure, as well as particular patterns, believe it or not, of breathing can impact sex steroid hormones, both estrogen and testosterone—the discussion isn’t really geared towards performance enhancement in sport, although we will do an entire episode, perhaps even an entire month, related to performance enhancement in physical enterprises.
So, one of the first things to understand if you want to optimize your hormones is where they come from. There are a lot of different glands in the body that produce hormones.
There’s the pineal gland. Some hormones are made in the hypothalamus. Hormones are made by the gonads, the ovaries, or the testes. You’ve got the thyroid gland. There are a bunch of different glands that make these different hormones, but when we’re talking about the sex steroid hormones, estrogen and testosterone, the major sources are ovaries for estrogen and the testes for testosterone, although the adrenals can also make testosterone.
Now, there are also some enzymes. Enzymes are things that can change chemical composition, and the enzymes that we’re going to talk about today are the aromatases. Mainly, the aromatases convert testosterone into estrogen, so in a male, for instance, that has very high testosterone, some of that is going to be converted into estrogen by aromatase, and aromatase is made by body fat. It’s also made in the testes themselves. A lot of people don’t realize this, but the testes actually have the capacity to manufacture estrogen and aromatase, albeit at low levels.
But this turns out to be important for optimizing hormone levels in males at later points, and we’ll discuss that. It’s important to note that there’s a huge range in terms of the levels of hormones, testosterone, and estrogen between individuals, and it actually occurs within individuals across the lifespan. I’m not going to throw out specific numbers of X picograms per deciliter, etc. today because that’s going to vary a lot. It’s going to depend on whether or not you’re measuring in picograms or nanograms and that sort of thing.
If you want to examine your hormones, you should do that in conjunction with a medical doctor. Ideally, an endocrinologist can help you sort out that information. But the important thing to know is that prepubescent females make very little estrogen, and when we talk about estrogen, we mainly talk about estradiol, which is the most active form of estrogen in both males and females. So, prepubescent females have very low levels of estrogen. During puberty, levels of estrogen, aka estradiol, basically skyrocket, and then across the lifespan, estrogen is going to vary depending on the stage of the menstrual cycle.
But as one heads into menopause, which typically takes place nowadays somewhere between age 45 and 60, levels of estrogen are going to drop, and then post-menopause, levels of estrogen are very low as well. Testosterone will fluctuate across the lifespan. Testosterone is going to be relatively low prepuberty in males. During puberty, it’s going to skyrocket, and then the current numbers are that it drops off at about a rate of 1% per year. Although we’re going to talk about some data that show that there’s actually tremendous variation in testosterone levels, there’s actually a lot of examples of men in their 90s who still have testosterone levels that mimic pubertal levels, which is remarkable and speaks to the huge variation in testosterone levels across individuals.
So, let’s talk about other sources of these hormones, and then it will make clear what avenues you might want to take in order to optimize these hormones. The other glands and tissues in the body that make these hormones, testosterone and estrogen, as I mentioned briefly, are the adrenals. So, the adrenals are right on top of the kidneys, and the release of these steroid hormones from the adrenals, in particular testosterone and some of its related derivatives, are mainly activated by competition. So, let’s talk about competition because it turns out that competition is a powerful influence on the sex steroid hormones, and the sex steroid hormones powerfully influence competition. So, most people don’t realize this, but most males of a given mammalian species never get to reproduce.
In fact, they never even get to have sex at all, and we don’t often think about that. But testosterone plays a powerful role in determining which members of a given species will get to reproduce, which ones of that species will actually get access to females. And so here I’m not talking about humans specifically, but it’s well known in species like elephant seals, in species like antlered animals and rams, for instance, that the higher levels of testosterone correlate with access to females. Now, one interpretation of this is that the females are detecting which males have high testosterone and selecting them. They’re more receptive to them.
We’re going to talk about receptivity for mating in a moment, but it’s actually more so that the males that have higher testosterone forage further and will fight harder for the females. And this is really interesting because there’s very good evidence now that testosterone can reduce anxiety, promote novelty-seeking, and promote competitive interactions. And so before you leap too far with this in your mind and think about all these human behaviors, just stay with me because there’s a little bit of biology here that makes it all make sense, and it turns out to be pretty simple.
We have a brain region called the amygdala. In Latin, that just means almond, but the amygdala is most famous for its role in fear.
We hear a lot about fear and the amygdala, but the amygdala is really involved in threat detection. It sets our thresholds for anxiety and what we consider scary or too much. Testosterone, secreted from the gonads and elsewhere in the body, binds to the amygdala and changes the threshold for stress. So, I’ve said before on previous versions of this podcast and on other podcasts that testosterone has this incredible effect of making effort feel good. But what I was really referring to is the fact that testosterone lowers stress and anxiety, in particular in males in a given species.
Now, this is important because we often think of testosterone as creating whatever masculinization or it’s virilization or all these terms are thrown around, but what’s it really doing when it comes to mate choice and competition? What it’s doing is it’s reducing the threshold for anxiety, and in doing so, it selects individuals of a given species to push further, being willing to suffer more, although it also reduces pain, so maybe they also suffer less in pursuit of reproduction and females. Now, it’s well known in humans that both males and females who have elevated levels of testosterone will engage in more novelty-seeking, and I do want to point out that even individuals without testes have testosterone, and peaks in testosterone have similar effects regardless of whether or not someone has ovaries or testes. Testosterone increases generally lead to more foraging, more novelty-seeking, increases in libido, and increases in desire to mate. So, it is the case that increases in testosterone promote competitive and foraging-type behaviors in humans and in nonhuman mammals.
But it’s also true that competition itself can increase androgens such as testosterone. I want to repeat that: competitive environments themselves can
