- 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, we are discussing skin health. Our skin is an incredibly important organ, not just for our appearance or because it serves as a barrier to the other organ systems of the body, but because it actually reflects the health status of all the other organs and systems in our body, including our brain.

As well, you'll learn today about the direct and reciprocal relationship between the immune system and our skin. And if you think about it, you've seen this relationship in action before. When any of us is feeling fatigued or sick, the color, the tone of our skin, tends to be a bit, quote-unquote, "off," at least for us, relative to what it normally is.

Conversely, when we are feeling particularly well-rested and vibrant and healthy, our skin reflects that. So today, we will discuss the skin as an organ. We'll talk a little bit about the biology of skin so that everybody's on board the nomenclature of the different cell types in the skin and how they're affected by various things.

And then we will discuss those things, such as sunlight and sun exposure as it relates to skin cancers. We'll talk about sunscreens, of course, something that I know garners a lot of interest these days and even some controversy. We will talk about common conditions of skin that concern people, such as acne, rosacea, psoriasis, eczema.

And of course, we will talk about so-called anti-aging treatments for skin. That is, the things that can be done to help reduce the degradation of the protein components in skin, things like collagen, things that you can do to improve collagen turnover, as well as elastin. These are other proteins within skin that give skin its youthful, or in some cases, where it's degenerative, non-youthful appearance, things like wrinkles and sagging skin.

So we'll talk about all of that. We'll also talk about the various products that have been developed in order to treat wrinkles, treat sagging skin, reverse acne, et cetera. We'll talk about which ones are safe, which ones are not safe, and which ones for which there still is no clear answer.

I want to make very clear here at the outset that while I'll discuss various skin products during today's episode, I nor the podcast has any financial relationship to those products. I will provide examples of certain products and provide a few links in the show note captions, but I want to point out that those serve merely as examples that I found during researching this episode, which by the way, included speaking to several board certified dermatologists, including a dermatologist expert in oncology, cancers of the skin.

So by the end of today's episode, you will have a much clearer understanding about skin and what it is at the level of biology and function, its relationship to other systems in the body, including the immune system and gut microbiome, and you will be armed with the knowledge to make the best possible decisions for you in terms of skin health and skin care, depending on your age, your goals, and any current conditions you may have.

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 Juve. Juve makes medical grade red light therapy devices. Now, if there's one thing I've consistently emphasized on this podcast is the incredible impact that light can have on our biology. Now, in addition to sunlight, red light and near infrared light have been shown to have positive effects on improving numerous aspects of cellar and organ health, including faster muscle recovery, improved skin health and wound healing, even improvements in acne, reducing pain and inflammation, improving mitochondrial function, and even improving vision itself.

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It's only about the size of a sandwich, so it's super portable and convenient to use. I also have a Juve whole body panel and I use that about three or four times per week. If you'd like to try Juve, you can go to juve, spelled J-O-O-V-V.com/huberman. Juve is offering an exclusive discount to all Huberman Loud listeners with up to $400 off select Juve products.

Again, that's Juve, J-O-O-V-V.com/huberman to get $400 off select Juve products. Today's episode is also brought to us by BetterHelp. BetterHelp offers professional therapy with a licensed therapist carried out entirely online. I've been doing weekly therapy for over three decades. Initially, I didn't have a choice. It was a condition of being allowed to stay in school, but pretty soon I realized that therapy is critical to overall health.

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If you'd like to try BetterHelp, go to betterhelp.com/huberman to get 10% off your first month. Again, that's betterhelp.com/huberman. Today's episode is also brought to us by Roka. Roka makes eyeglasses and sunglasses that are of the absolute highest quality. I've spent a lifetime working on the biology of the visual system, and I can tell you that your visual system has to contend with an enormous number of different challenges in order for you to be able to see clearly from moment to moment.

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What should we all be doing to take care of this organ that we call our skin? Now, our skin is a very interesting organ, as I mentioned earlier, not just because it protects all the other organs of our body, and I should mention it protects them not just by a physical barrier, but there's also chemical things, a chemical composition, a skin microbiome to the skin that also provides additional layers of support, such as neutralizing different bacteria that land on your skin.

There's a lot more to skin than you might realize, but to start off, let's just talk about what skin is at the level of its structure, some of the cell types, because in understanding that you'll be best equipped to understand some of the recommendations for skin health and skin care.

The skin, like many other organs in the body, is a layered structure. So the very outermost layer is called the epidermis. The epidermis has cells in it, below that, there are other cells that comprise what's called the dermis, or sometimes referred to as the dermal layer. And then beneath that, you have subcutaneous fat.

Now, of course, in different areas of the body, the skin, and as a consequence, these different layers of the epidermis and dermis and the fat layer below it are of different composition and different thicknesses. Think, for instance, about the thickness of the skin on your forearm versus the thickness of the skin on your belly versus the thickness of your skin on your eyelid.

Okay, and as soon as you think about your eyelid, you realize, okay, this thing that we call skin varies tremendously in thickness, depending on whether or not we're at the scalp, the eyelid, the face, the chin, even neck versus chin, body, et cetera. So what we think of as skin, while it may have a designated set of layers that have particular names, can vary tremendously in terms of its overall thickness, and therefore its vulnerability to things like sunlight, which indeed can mutate the cells within the skin, cause them to have dysregulation of the expression of DNA and the production of other cells.

We'll get into that. So I just want you to think about skin as having these critical components of layers, epidermis and dermis below it. And by the way, within the dermis is where you're going to find the blood supply, the vessels and capillaries that innervate the skin. Innervate simply means that supply or go to the skin.

You of course have hair follicles and hair growing out of those follicles in many cases. And then of course you have skin that does not have hair, the so-called glabrous skin, like on the palms of your hands, the bottoms of your feet, et cetera. So I don't want to give the impression that skin is the same everywhere.

It varies in thickness. It varies in terms of the presence of hair or lack of hair. It varies according to a lot of different parameters, including how much oil is produced in one region or another. But if you just know that the skin has an epidermis, an outermost layer, a dermis, or sometimes referred to as the dermal layer, which is below it.

And then it has fat below that. And that the vasculature, right? The vessels and capillaries are at the level of the dermis. They come up through the subcutaneous fat and into that dermal layer, but they don't reach into the epidermal layer, that outermost layer. And if you understand also that nerve endings, okay?

The little terminals, as we call them, of neurons, nerve cells, also go up into that dermal layer. You've got temperature sensors in the skin. All of this becomes very important for our discussions of skin conditions. Things like rosacea, things like acne, which sometimes can be painful or can be exacerbated by things like heat.

They can be suppressed in some cases or even activated by things like cold, okay? So if you just understand that there are three layers, epidermis on the outside, dermis below it, subcutaneous fat, and that skin varies in thickness, and that nerves, that is nerve endings and blood vessels and capillaries are within the dermal layers of the skin, well, you're going to be very well equipped for the rest of today's discussion.

I'll throw in some additional information about oil production within the hair follicle and a few other things like extracellular matrix, which as the name suggests is extracellular. It's outside where the cells reside, but gives it its composition as either plump and moist appearing on the outside, or it can be kind of sagging and wrinkled and dry appearing.

All of that relates to the different components of proteins and other things within those skin layers. But if you understand what I just told you, even at a crude level, if you can just imagine it just a little bit, those three layers, you're going to be very well equipped for the rest of today's discussion.

I should also mention that there are glands within the skin. This won't be surprising to most of you. Those glands will produce oil either more or less, depending on certain conditions. And there are things that live on the skin, on that epidermal layer and within it that we call microbiota.

You've no doubt heard of the gut microbiome, right? The existence of trillions of little micro bacteria that live within your gut, that provided they are varied in their composition and of the right sort, really support your immune system and other aspects of health, including brain function and health. Well, you also have a skin microbiome.

That is the existence of microbiota on the outside of your skin that serve as a barrier to infections, but that also provide things that are nourishing to the skin and give it that vibrant look that most people want. And by cleansing your skin in particular ways, that is washing it with certain substances and avoiding other substances, you can support as opposed to diminish that skin microbiome.

Okay, so to start today's discussion, I want to jump right into the deep end, meaning into one of the more controversial issues related to skin health and skincare out there right now, which is sun exposure and sunscreen. Now, it makes sense why this would be such a heated issue, no pun intended, because most everyone is exposed to the sun or has the opportunity to be exposed to the sun to some degree or another every single day, even on cloudy overcast days.

It's also the case that we've learned a lot in the last 10 years or so about how different sunscreens and their components may be good for us, may be less good for us. And today we're going to talk about what is known and what is still unknown. But before we do that, we need to take a step back and look at the context in which all this controversy is happening.

My read of the online community as a whole, as it relates to sunscreen and sun exposure in particular, is the following. I think most everybody, I didn't say everybody, but most everybody out there seems to accept the idea that excessive sun exposure can cause certain cancers of the skin.

That's the general belief out there. And there is good reason for that belief, because indeed the sun as full spectrum light includes long wavelengths. It's probably easier to think about those long wavelengths as the reds and oranges and yellows and so forth that are present. And well, they're always present from sunlight, but they're most obvious to us when the sun is low in the sky, so-called low solar angle sunlight at sunsets and also at sunrise.

But of course, as full spectrum light, sunlight also includes UV, ultraviolet light of different types. We'll talk about those types today, as well as blue light and green light. And in midday sun, when the sun is overhead, we just see the sun as white light, right? Because it's containing all those different wavelengths.

So while this is not a discussion about wavelengths and optics, for sake of today's discussion, just understand that long wavelength light tends to be more of the red, orange, yellow variety, okay, loosely speaking. And down at the other end of the spectrum, the short wavelength light is more of the blue and green and so-called ultraviolet light.

So it's well accepted light of different wavelengths, such as UV, blue light, green light, all the way out to red light, even near infrared light can penetrate into cells. It can actually pass through surfaces. It turns out that long wavelength light can actually go deeper into the surface of our skin, right?

It literally can penetrate just by shining a red light on your skin. It can actually penetrate the skin to a deeper layer than can short wavelength light like UV light. And it's well accepted that UV light, when it penetrates mostly that epidermal layer of the skin, that outermost layer, it can cause changes in the way that DNA functions.

It can cause mutations such that DNA, which as many of you probably remember from high school biology, DNA is transcribed into RNA and RNA is translated into proteins. The proteins are the things that the cells produce. They're actually made up of proteins. Well, UV light can disrupt which DNA are expressed and how they are expressed, in some cases leading to overproduction of too many cells or disruptions in the functions of cells.

And that's why people link UV light to skin cancer. That's the whole idea there. And that's the whole notion behind using sunscreens. And notice I'm saying sunscreen. So ways to screen out UV light or maybe all sunlight in some cases, in order to prevent that penetration of the UV light into cells, which can cause mutations, which in some cases can lead to skin cancer.

Now I realize as I'm saying this, there's probably a group of you out there saying, what's the evidence that sunlight can actually cause skin cancer? Well, there is clear evidence that sunlight can cause skin cancers. Which skin cancers and how deadly those skin cancers are, we'll get to in a few moments.

That turns out to be a very interesting twist in the whole story. But I want to highlight the fact that there's very little controversy as to whether or not UV light can cause mutations in cells, right? But what you should be asking yourself is, well, why would long wavelength light like red light perhaps be good for skin?

We'll talk about that later. There are therapies, phototherapies that use, that exploit red light, which can penetrate deep into skin that actually can enhance the health of skin if done correctly. Whereas short wavelength light, which only hits that epidermal layer on the outside of the skin, may be bad for our skin.

And I say maybe because it's really a function of dose and timing and genetic background, okay? If all this is seeming rather complicated, I'm going to make it very simple. And before I do that, I do want you to ask yourself a question. I want you to ask yourself where you reside on the continuum of beliefs about sunscreen, UV light, and skin cancers.

So here it goes. My read of the landscape out there is that there are some people, it's a small minority, but there are some people who feel that sunscreen in any form is bad for them. They think, okay, sun is great for them and sunscreens of any kind, chemical or physical barriers, bad for them, okay?

Some people believe this. I'm not saying I believe this. In fact, I don't believe that. I'm a big believer in sunlight and the power of sunlight for health, but I am not what is called a sunscreen truther, okay? I'm not somebody who thinks that sunscreen has no value. In fact, quite the opposite under certain conditions and certain sunscreens.

I want to say that for the record. Other people out there believe that certain sunscreens can be valuable, but only the sunscreens that lack certain chemicals because they are concerned about chemicals in certain sunscreens being so-called endocrine disruptors or maybe even causing cancer on their own, okay? Other people are so afraid of sunlight and believe that it causes so many issues as it relates to skin cancer that they basically create beekeeper uniforms for themselves so that anytime they're out in sunlight, they want to have sunglasses on, they want to have a hat, they want to cover their neck, every part of their body, okay?

They sit at the opposite extreme of the people who don't believe in using any sun protection whatsoever. And now, of course, there's the backdrop of how much natural melanin production we each make, that is how dark our skin happens to be according to our genetics. And of course, there's the issue of where we live on the planet and how much sun we have available to us in order to potentially expose ourselves to.

And perhaps also ask yourself, if you are in what I believe is the largest category of people out there, which is the category of people who probably don't wear sunscreen every day, maybe they put it on occasionally, but only if it's very bright out, very hot out, because they don't want to get a so-called sunburn.

And I believe most people fit into that general category of A, not wanting to be burned, B, not wanting to age any faster than they would were they to not wear sunscreen, at least that's their belief, and C, they've just been told that sunscreen is good for them and they'll reach for whatever sunscreen is on the shelf or that was recommended to them either by their dermatologist or that they happen to find in the pharmacy or when they're out skiing and they notice it's a bright day and so they buy some sunscreen and slather it on.

So before I go any further, just ask yourself those questions. You know, where do you reside? Are you afraid of sunscreen? Do you love sunscreen? Are you in the beekeeper category? Like you think all sun is bad, it's going to give you skin cancer, it's going to age you faster.

We'll get to the aging component in a few minutes, but just ask yourself that question as we wade into the material I'm about to cover. So what's the story with sun exposure, sunburn, sunscreen, skin cancer, and aging? I spoke to several different dermatologists about this, including one expert in skin cancers specifically.

And what I was told is the following. First of all, sun exposure will disrupt the collagen and elastin, but mostly the collagen composition of your skin in a way that makes it appear as if you're aging faster. Okay, so sun exposure, yes, ages the skin. Now that does not mean, however, that you want to avoid all sun exposure because the same dermatologist said that some sun exposure is healthy for us.

Why? Because our skin is also an endocrine organ. It's involved in making various hormones. It's part of the vitamin D production pathway. Although a little bit later, we'll talk about the fact that most people get their vitamin D from their diet, and in some cases also from supplementation. But it is a good idea to get some sunlight for sake of vitamin D production, but also the production of other hormones like testosterone and estrogen.

Okay, so every single dermatologist that I spoke to said that some sun exposure is good for us, but that too much sun exposure will accelerate the appearance of aging in our skin. So let's pin that up on the wall as fact, okay? This again is not saying you should avoid sun completely.

It's also not saying you should get excessive sunlight exposure. It's saying sunlight exposure by virtue of the UV wavelength's ability to cause mutations in the epidermal layers of the skin and to impact the collagen composition of the dermal layers below it, as well as some of the other proteins present in the keratinocytes, okay?

One of the major skin cell types and other cell types of the skin does lead to the appearance of aged skin, which is one rationale for wearing sunscreen. Now, when I say sunscreen, everyone, including myself, thinks about lotions or in some cases, sprays. But let's pay attention to the one fact that I do think everybody, regardless of what category they are in the general population, or what background training a dermatologist has, believes, which is a physical barrier, a shirt, a hat, a jacket, a physical barrier can provide, in some cases, very good protection from the sun.

And I don't think there's any controversy whatsoever as to whether or not the composition of the physical barrier is having negative effects on the skin, okay? You will find those niche communities out there that are saying, okay, certain chemicals present in certain materials that clothing are made with can be problems for the endocrine system, but we're not talking about that here, okay?

What I'm saying is that all dermatologists I spoke to, and I think most every rational human being on earth, would say that a physical barrier can help to a great degree in order to protect our skin from the sun as it relates to sunburn, but also acceleration of the appearance of aging in our skin.

Okay, so I don't think there's any dispute about physical barriers for protecting the skin. How much you want to protect your skin from the sun, well, that will depend on what category you decided you were in from the earlier discussion. We'll get back to that. What else did all the dermatologists and skincare experts that I spoke to also agree upon?

Well, they all said that indeed, excessive sun exposure can increase the propensity for certain skin cancers. I want to go on record by saying, I believe that. Why? Well, because of this ability of UV light and some other wavelengths of light potentially to cause mutations in skin cells that can lead to certain skin cancers, okay?

I don't think that's a debated topic out there. There might be a few people out there who are going to hang their hat on a study that I'll go into in a little bit later, which is that the relationship between sun exposure and all-cause mortality is a tricky one.

It's one that we'll parse, okay? Meaning, I'll just give it a little hint into what I'm saying. People who avoid the sun entirely don't tend to live as long as people that get some sun exposure, but there are a bunch of confounding variables that have to be understood in order to really interpret that statement and the study that we'll parse a little bit later.

For now, let's just accept the reality that the vast, vast majority of dermatologists out there and skincare experts really understand that sun exposure can accelerate aging of the skin, but most will also tell you that some sun exposure is good for you, not just for skin health, but for overall brain and body health.

Now, as it relates to skin cancer, the dermatologist oncologist that I spoke to, all right, who did his training at Stanford, and I'll provide a link in the show note captions to his clinic, and you can learn more about some of his work. He's published some really nice papers, said the following, and this was surprising to me.

He said, "It turns out that the skin cancers that sun exposure causes, while they can be serious and should be taken seriously, they should be treated, those generally are not the most deadly of the skin cancers." Now, why would he say something like that, okay? He said it because it turns out that there are lots of different kinds of skin cancer.

Some of them arise or can arise through sun exposure. Others, and indeed, some of the most deadly of skin cancers are independent of sun exposure. And this is where things can get a little bit tricky. You'll hear out there, oh, you know, sun can cause skin cancer, but not the skin cancers that kill you.

I don't think that's really a fair statement. You'll also hear, however, that all the skin cancers that are out there are the consequence of sun exposure, and that also is not true. And if anything, this provides motivation, not just on the part of the dermatologist, but it should be motivation from within all of us to make sure that we understand our background genetics, not just how much pigmentation we carry in our skin by virtue of our genetics, but we should know by asking, if you're not going to get genetically sequenced, which you can do nowadays, of course, but you should know whether or not your family, your genetics tends to carry certain mutations that make you more prone to skin cancers in general, not just the type that can be exacerbated by sun exposure.

What I'm basically saying is that if you have particular genetics in your family, even if you avoid all sun exposure, you know, nobody should do that, of course. You need some sunlight. I mean, like all other, or most all other creatures on earth, sunlight is important for us. It's important for setting our circadian rhythms.

That's why I'm always telling people to get sunlight in their eyes early in the day, which by the way, when the sun is low in the sky, low solar angle sunlight, the UV index tends to be very low, okay? So you are at the lowest possible risk of getting burned, of getting any kind of mutations to your skin.

That doesn't mean you should overdo it. It doesn't mean you should stare at the sun and damage your eyes. I've talked about this a lot on other podcasts, how to get morning sunlight exposure properly. But when the sun is low in the sky, that's generally a safe time to get sun exposure.

It's that midday sun, typically between the hours of, you know, 11 AM or even 10 AM, depending on time of year and where you're at, and two or three or 4 PM that the sun is overhead and at its greatest intensity and where the UV index can be very high.

It's very easy to look up the UV index. And when the UV index is very high, right? I was down in Australia earlier this year and the UV index down there is so high. You can almost feel it. You actually can feel it. You step outside and you immediately feel like, wow, my skin is really being bombarded with the sunlight.

And I'm somebody who tolerates sunlight pretty well because my dad's fairly, you know, dark pigmentation just naturally by virtue of being South American. Normally I can tolerate the skin pretty well, but you should not rely on just that subjective feel. You should look up the UV index and we'll provide a few links of good UV index sites that you can look up the UV index and where you might want to be extra cautious about providing a physical barrier or a chemical barrier to protect your skin.

Now, a lot of people out there also believe that if you avoid sunburn, you're avoiding skin cancer. Perhaps you're very pale or it's the early phase of the summer season, or you have a susceptibility to sunlight such that, you know, you step outside and you get too much sunlight on a given day and you get a sunburn, that reflects an immune reaction, an inflammatory reaction within the dermal layers of the skin.

So that means the vasculature, right? Those vessels and capillaries, they're going to dilate. You oftentimes will get infiltration of things like cytokines, which are of the immune system. You get an inflammatory response. That's why it's red. That's why it's tender to the touch. The nerve endings there can be overly activated.

So the reason why your skin actually feels warm, right? When you touch your sunburn is because in fact, you have an activation of some of the nerve endings at that site, as well as the activation of the local immune system properties that give rise to, again, vessel and capillary dilation.

It's a wound of sorts induced by excessive sun exposure. Now, does sunburn cause skin cancer? There's no direct relationship between sunburn and skin cancer, except the fact that sunburn reflects excessive sunlight exposure. And yes, as I mentioned before, it's conclusive that excessive UV sun exposure to the skin can cause certain mutations in skin cells that give rise to certain skin cancers.

Why are we parsing things at this level of detail, right? Is this all just semantics? No, it's not just semantics. Many people believe that if they didn't get a sunburn, they are not at additional risk for inducing skin cancer or other issues with skin, right? We're not just talking about skin cancer.

We're talking about accelerated aging of the skin, according to sun exposure. So let's make this very simple. You don't need a sunburn for the sun to accelerate the aging appearance of your skin. You don't need a sunburn to induce the kind of mutation that may, again, I want to highlight may, give rise to a skin cancer.

It's also not the case that if you've got a sunburn or even multiple sunburns, that you'll necessarily develop skin cancer. Although by virtue of the fact that sunburn reflects UV exposure, multiple sunburns would reflect increased UV exposure and therefore increase risk for certain skin cancers. So all of this to say, avoid sunburn however you can.

And if you're somebody who just loathes sunscreen, that doesn't want to even hear the discussion we're about to have next about which sunscreens are safe and which ones appear to be less safe, if you're just one of these people that does not want to put sunscreen on because you're very concerned about whatever chemical might be in sunscreen, well then consider that the physical barrier of an article of clothing or a hat or a bandana of sorts can indeed shield you from the sun to some degree, often to a great degree.

And again, I don't think there's any controversy as to whether or not those are safe. As many of you know, I've been taking AG-1 for more than 10 years now. So I'm delighted that they're sponsoring this podcast. To be clear, I don't take AG-1 because they're a sponsor, rather they are a sponsor because I take AG-1.

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Again, that's drinkag1.com/huberman. Okay, so before we dive into our discussion about sunscreens and the chemicals in sunscreens, let's just take a moment and talk about vitamin D. Vitamin D is important for a great number of bodily and brain functions. As I mentioned earlier, most people get their vitamin D from the foods they eat.

If you eat dairy, in most countries, the dairy is fortified with vitamin D. Many people nowadays supplement with vitamin D anywhere from 1,000 IUs to 5,000 IUs. There are folks out there who perhaps even take 10,000 IUs, seems a bit high for most people, but it's going to depend on how much sun exposure you get, the pigmentation of your skin.

But there are a number of people, especially in countries where they don't get a lot of sun exposure in particular times of year, and maybe they're not eating enough dairy fortified with vitamin D, who would benefit from vitamin D supplementation. And many people find they feel better when they supplement with vitamin D, but I encourage you that if you're going to supplement with vitamin D to probably start at the lower end of supplementation, like 1,000 to 3,000 IU, maybe 5,000 IU, best would be to measure your vitamin D levels.

Many people are surprised to find that even if they live in a part of the world where they get a fair amount of sun exposure and they eat some dairy that's fortified with vitamin D, that for whatever reason, their vitamin D levels are still too low and benefit from supplementation with vitamin D.

The dermatologist that I spoke to told me that yes, even if you wear sunscreen or a physical barrier, okay, this is interesting. Even if you wear sunscreen or a physical barrier when you get outside into the sun, it can still have a positive effect on your vitamin D levels.

This was surprising to me, but then of course it makes sense. Sunlight is full spectrum light. It's not just UV and short wavelength light. The ability for longer wavelength light to penetrate the skin is clear. And those longer wavelengths can also impart a positive influence on the vitamin D pathway.

Okay, so if you're concerned about wearing sunscreen because you're worried that it's going to impair your vitamin D synthesis or metabolism in any way, probably no reason to be concerned. Now, if you're somebody who is in the beekeeper category, who's completely avoiding sun exposure for whatever reason, well, then you probably want to get your vitamin D levels checked and you may want to rely on supplementation or something of that sort.

At the same time, because of variation in genetic background, there will even be some of you out there who are super anti-sunscreen, who are peeling your shirts off all the time, who are getting lots of sun exposure, who may surprisingly have vitamin D levels that are still low. That's rare, okay, for all the obvious reasons, but it could still be the case.

And indeed, some of the dermatologists that I spoke to said they occasionally have a patient like that. Vitamin D, as you may recall, is involved in a bunch of different things. It acts as a hormone. It's involved in calcium absorption. It's involved in some of the other hormone pathways.

And I should mention that there's a study, I'll link to this in the show note captions, that shows that some amount of sunlight exposure to the skin, this is an Israeli study where they had people, you know, get several tens of minutes of sunlight exposure in the afternoon during particular times of year.

They didn't have them going naked outside, okay? This was sort of like context and culturally appropriate. Skin exposure to the upper body and to the legs could induce increases in hormones such as testosterone and estrogen, which were correlated with, it wasn't causal, but it was correlated with improvements in mood, well-being, libido, et cetera.

Well, some of that probably relates to testosterone and estrogen synthesis directly. Again, the skin as an endocrine organ, okay? There are certain elements within the keratinocyte skin cells that can literally communicate with some of the organs of the body that produce testosterone and estrogen, even some of the glands, pituitary, et cetera.

This is through a number of different stations. It's not necessarily direct, but also through the sun's ability to impact the vitamin D pathway that then impinges on those testosterone, estrogen, and things like luteinizing hormone pathways. We don't have time to go into all this now. I covered this in an episode about testosterone and estrogen.

You have hormones such as luteinizing hormone, which then stimulate the gonads, the testes to the ovaries, to make testosterone and/or estrogen. The skin is a not so obvious player in this whole thing, whereby external environmental stimuli, such as the availability of sunlight, which in most places in the world varies across the year, can stimulate more or less vitamin D production, luteinizing hormone production that can impinge on testosterone and estrogen production.

These pathways are one of the reasons why when we get the right amount of sunlight, not too little, not too much, we feel better. We feel better because certain hormones are being produced at certain levels when we're getting that sun exposure. And when we don't get that sun exposure, we have lower levels of those hormones.

This is well-established. And the study that I linked to in the "Show Note" captions, which I've covered in previous episodes, is but one example of that phenomenon. Okay, let's talk about sunscreens. Now, the reason I changed my tone of voice with this is that if you look on the internet, you will see claims that I don't use or believe in sunscreen, and that is just false.

I've worn sunscreen my entire life. I don't necessarily wear it every day. I don't tend to burn easily, okay? I have some natural level of pigmentation in my skin based on my genetics, as I mentioned earlier. But as we talked about earlier, just avoiding sunburn is not going to protect me or anyone else against certain sun-induced mutations in skin cells and the aging effects that sun can have.

So I do believe in certain sunscreens, meaning I will put sunscreen on on certain days, on certain parts of my body. However, I do believe, now having spoken to multiple dermatologists and looked into the literature very deeply, that there are certain chemicals in certain sunscreens that are of concern.

I don't mean that if you put these on once or even twice, that you are going to suffer negative consequences. I mean, they are of concern, meaning we should pay attention to them. And when given the option, we should opt for the healthier choices. And in fact, there are known healthier choices.

To make all of this very clear, I'm going to tell you what is very clear to the dermatology community at this point in time, okay? In June of 2024, here's what we know. There are two major types of sunscreens out there. Well, really three. We talked about physical barrier before.

No one argues about a physical barrier. No one's worried about the chemical composition of physical barriers, okay? When we talk about sunscreen, so lotions, creams, sprays, et cetera, there are two major types. The first are organic types, which is essentially chemical sunscreens, okay? So when you hear organic sunscreens, that means chemical type sunscreens.

And then there are inorganic types, which are sometimes referred to as mineral-based sunscreens. Here's what most everybody seems to accept, that mineral-based sunscreens, meaning sunscreens that tend to include either zinc oxide or titanium dioxide, or both in some cases, are generally thought to be safe up to concentrations of 25%.

25% is a pretty high concentration. You can find sunscreens out there that have 25% zinc oxide or 25% titanium dioxide. They're rare to find, however. More often, you'll find sunscreens that have 15%, 10%, 18% zinc oxide, sometimes alone, or in combination with titanium dioxide. You'll find some pure titanium dioxide sunscreens out there, although those are a bit more rare, right?

A little bit harder to find. Here's the story. Zinc oxide and titanium dioxide reflect back UV light, the short wavelengths of light, that would otherwise potentially cause mutations in your skin cells at the level of the epidermis, okay? In the outermost layers of skin. Remember, short wavelength light doesn't pass very deeply into the skin.

Sunscreens containing zinc oxide and/or titanium dioxide were engineered for that specific purpose, to reflect back UV light. This is very different than organic or chemical sunscreens, which contain certain compounds. These go by different names, oxybenzone, avobenzone. There are a bunch of these different chemicals that are contained in so-called organic or chemical sunscreens.

Those chemicals, in general, don't serve to reflect back UV light, but rather absorb UV light, okay? So when they're applied to the skin, they're designed to absorb the UV light so that the UV light can't negatively impact the skin. Those chemical, again, chemical, aka organic components within organic sunscreens, again, sometimes called chemical sunscreens, are designed to absorb UV light.

Mineral-based sunscreens, so-called inorganic sunscreens containing things like zinc oxide or titanium dioxide, are designed to reflect back UV light. Why am I telling you this? Well, I'm telling you this because it's generally believed that the zinc oxide and titanium dioxide containing sunscreens are safe up to concentrations of 25%, whereas there is some, again, some concern about the chemicals within chemical, aka organic sunscreens, as potential endocrine disruptors, so disrupting things like testosterone synthesis, estrogen synthesis, and other hormones.

It's not all just about testosterone and estrogen, folks. Other hormone pathways that many people, including some governing bodies and agencies that assess the safety of different cosmetic and sunscreen products are concerned about. Now, how concerned they are depends on where you are in the world, okay? So in Europe, they have different stringencies for what is considered safe versus unsafe or just of concern, as opposed to in the US.

Here's what every dermatologist in the US, 'cause those are the ones I spoke to, told me, which is that it is advised that on children younger than six months of age, you do not use chemical-based sunscreens. Why? Well, young skin, even the skin on the external part of the body, in children six months or younger, acts more like mucosal skin in that it can very easily absorb things transdermally through the skin.

However, even as we age, so into puberty, our young adult years, and even into our elderly years, there is still a capacity for things to pass transdermally through the skin, although because of some of the additional barriers formed within the dermal and epidermal layers of the skin, things like extracellular matrix, the changes in collagen, et cetera, there is less tendency for compounds to pass transdermally through the skin.

Now, that just simply highlights the fact that if you are a very young person or if you're applying sunscreen to a very young person, maybe six months or younger, but also perhaps older, depending on how careful you want to be, to avoid these chemical-based sunscreens. There is very little, if any, evidence that the mineral-based sunscreens are of concern for transdermal passage into the skin at concentrations of 25% or less, meaning sunscreens containing zinc oxide and titanium dioxide are probably safe, or at least have been deemed safe enough that they are freely available on the market, and we are told that they are safe for people of all ages.

So if you are somebody who is concerned about the chemicals in sunscreen, most every dermatologist or chemist who works on sunscreens will tell you, well, mineral-based inorganic sunscreens are going to be your safer option if you're concerned. But get this, the chemical-based sunscreens, while some of the chemicals in them, indeed, can be quite scary when you read the literature, you look at some of these things like oxybenzone, avobenzone, and some similar chemicals, even at low concentrations, have been shown to be endocrine disruptors.

People talk about how the fact when they apply these sunscreens, they can taste them in their mouth. There's a lot of fear around these, and some of that fear is substantiated. When one goes and looks at the studies that have been done on these chemical-based sunscreens, you may find it interesting to note that the way these studies were done often involves having people apply a ton of these chemical-based sunscreens, like two full bottles of these sunscreens over the course of a very short period of time, and then have their blood drawn, and then it's revealed that some of these chemical components are within the blood.

So a big issue that's not often discussed because it's very difficult to control for in a natural setting, but is straightforward to control for in a laboratory setting is how much sunscreen one is applying and how often, and across how many years of time. So there's no real prescriptive that can tell you, hey, if you put chemical sunscreens on once, that's problematic, although certainly pay attention to that six months and younger, what is essentially a rule that I mentioned earlier, and do not put chemical-based sunscreens on really young kids.

You might want to avoid them entirely, depending on how stringent you are about this stuff. But when it comes to chemical-based sunscreens, personally, I avoid them, but then it becomes a question of if you could only use a chemical-based sunscreen, you simply look at the label. Some of these have, by the way, zinc oxide, titanium oxide, and chemical-based components.

Okay, keep that in mind. Some are purely mineral-based, some are purely chemical-based, but if you look at a sunscreen label, you know, okay, well, this is the only thing available on this very hot day with a very high UV index, and otherwise I'm going to get a burn. Well, if you're really concerned, then I would resort to a physical barrier.

If you are less concerned, then you could perhaps tell yourself, okay, you get to put it on that day, but you might not want to use it every day, and you might want to use a small volume of it, right? Or maybe just on parts of your face or your ears or your neck that are particularly sensitive to sun.

Okay, these are the things that need to be taken into consideration. But when we step back from all of this, all of the literature, including, by the way, some of the literature that assessed, and I'll put a link to this review, a review on the potential neurotoxicity of titanium dioxide nanoparticles.

I'll get into this in a moment. It has been explored whether or not titanium dioxide is more risky than zinc oxide. We'll talk about that in a moment. But when you step back from all of this, here's what you get. Physical barrier, no one argues about that. No one believes that clothing is dangerous per se when it comes to avoiding excessive sun exposure.

Again, excessive relates to your skin tone, your background genetics, your activities, and where you are in the world and what time of year, okay? Very specific to your needs. Very few folks are concerned about mineral-based inorganic sunscreen. So if you want to use sunscreen, as many people do, and you want to make sure that it's not an endocrine disruptor and it's not a neurotoxin or something else that's been raised for some of these chemical-based sunscreens, well, then find a sunscreen that has 25% less zinc oxide and/or titanium dioxide.

If you were a bit more concerned about, say, titanium dioxide and some of the suggestive evidence, only suggestive evidence that maybe titanium dioxide is more risky than zinc oxide, especially when it's in its nano form, the very small form that may indeed allow it for more easy passage through the layers of the skin, that transdermal passage, well, then find a sunscreen that is purely zinc oxide sunscreen.

And again, they always have other things in them, but what I mean is the only active ingredient in a zinc oxide-only containing sunscreen is zinc oxide, and then there are a bunch of other things that allow it to be a lotion, for instance. Again, up to 25% concentration. Why would somebody not want to use zinc oxide containing sunscreen up to 25% and opt for anything else, you might ask, right, if that's considered safe?

The reason is the consistency of the zinc oxide is it's pretty sticky and thick and it's kind of pasty, right? Back in the '80s and '90s, some of you may recall that zinc oxide sunscreens that would actually color the nose white, so you could really see it, it was really prominent on the face.

They tried to turn that into a fashion statement and didn't go over so well over time. But in any case, the addition of titanium dioxide to those zinc oxide-containing sunscreens allow it to be a bit silkier so that it would spread on more evenly. And then you may say, well, why even put chemicals in sunscreen at all if there's risk?

The reason why chemical-based organic sunscreens even exist is that they can come up with compositions of those sunscreens that are very silky then that could spread on clear over makeup and things of that sort. But there are these concerns about some of those chemical components as endocrine disruptors and potentially as mutagens that could cause other issues or any number of different things.

You can find all sorts of concerns out there on the internet. Most of those concerns are not substantiated, but these chemicals can be problematic at high concentrations. And that takes us back to the point made earlier, which is that in the studies of those chemicals and the reasons, in some cases, being banned in certain countries and other countries carrying warning recommendations, the amount of those chemical-based sunscreens that were applied was exceedingly high.

So if you're wearing sunscreen very often, you're wearing a lot of it, probably best if you're towards a mineral-based sunscreen. If you are concerned at all about the chemicals in chemical-based sunscreen, wear a mineral-based sunscreen and/or use physical barrier. And if you're somebody who just doesn't believe that sunscreens are safe whatsoever, well, you know, as far as I know, it's a free world.

You don't have to wear sunscreen, but then I would say you need to be very aware of the fact that sun can induce the appearance of accelerated aging in the skin, right? That's an actual process that takes place. There's really no debating that, frankly. And sun exposure can potentially accelerate or even give rise to certain skin cancers, and nobody wants that.

Okay, before we move on to a discussion about what can be done to increase the youthfulness of our skin or the appearance of youthfulness in our skin, we need to have a bit more discussion about skin cancers. Notice I said skin cancers, plural, because there are many different forms of skin cancer.

Some of them relate to sun exposure, as we discussed earlier, others do not. And in fact, some of the more deadly skin cancers are independent of sun exposure. They can relate to genetics and to other factors. So the most straightforward story about all of this is that approximately 80 to 90% of melanomas, which are skin cancers, and they are very serious skin cancers that can indeed be very deadly, arise in what's called de novo skin.

De novo skin is non-mole skin. Now, does that mean that you should not pay attention to the shape and any changes in your moles? No, you absolutely should. But for people who have naturally darker pigmentation everywhere or who have very few moles, then you aren't going to be able to use the monitoring of your moles as the only readout of potential development of skin cancer.

And frankly, everybody should be thinking about these more serious skin cancers independent of moles or changes in moles. Here are a couple of things that everyone should pay attention to. If you have a pimple-like lesion, or you have any kind of spot on your skin that seems like it's an acne that's lasted more than a month, or you have an area that's seeping something that might look like plasma or pus or blood, and it persists over a long period of time, like a month or more, absolutely get that checked out by a dermatologist, okay?

Don't wait any longer than a month, get it checked out. In addition, it's highly recommended that you go in and you get your moles checked by a dermatologist. And frankly, that you get all of your skin checked by a dermatologist at least once per year. This is going to really protect you against both the sun-induced skin cancers and other forms of skin cancer, the most common form of sun exposure-induced cancers are basal cell carcinomas.

And indeed, those are less deadly than many of the melanomas, but they still can be exceedingly problematic and they can be deadly. So it's very important to get these checked out. Now there are websites, and I'll provide a link to one of them in the show note captions, for which you can look at a bunch of different examples of different moles and how they change over time.

And if you happen to have a mole that resembles the appearance of any of the moles in that image gallery, then you would be wise to go to a dermatologist right away because it could be, again, could be cancer of some sort. You do not want to let these things linger for too long.

At the same time, many people get concerned about one mole that didn't have an irregular border and then suddenly has an irregular border. There are a lot of different features that you'll learn from the website, or if you talk to your dermatologist that relate to whether or not something is predicting skin cancer or has become skin cancer.

It's not just irregular border, it's changes in size, certainly changes in pigmentation, vascularization, bleeding, any kind of seeping. There are a lot of different things there. So don't be alarmed at first appearance of one of these things, but do take it seriously. And keep in mind that there are things that your dermatologist can do to help prevent certain skin cancer.

So for instance, there's a growing trend now among dermatologists to suggest laser resurfacing of skin. That is a laser used to essentially disrupt that epidermal outermost layer, turn it over so that it regenerates 'cause it can indeed regenerate to create new cells there. Keep in mind that UV light and other factors in the environment can cause mutations within that skin layer.

Sometimes they're caused by genetic factors, but often environmental factors like sun and chemicals and other things. And by encouraging turnover of that skin layer through laser resurfacing, which by the way, may also increase the sort of youthfulness appearance of your skin, so many people are motivated to do it for that reason, can dramatically reduce the incidence of certain kinds of skin cancer.

In fact, the dermatologist that I spoke to who's an expert in derm oncology, okay, cancers of the skin, said that laser resurfacing can cause a 30% reduction in skin cancers because of this ability to rejuvenate that epidermal layer. And that's especially true for areas of the body like the face, ears, neck, tops of the hands, et cetera, for which the sun often induces the most damage because those are the most exposed parts of the body on a regular basis.

And by the way, this whole thing about skin cancer is not a trivially small number, it's a big number. In the US alone, there are up to 4 million cases per year of what's called squamous cell carcinoma, one of these forms of skin cancer. So getting checked out by a highly qualified dermatologist on a yearly basis, maybe even more, if you're really concerned about this, 'cause you have a lot of familial, genetically inherited skin cancers, things of that sort is really highly advised.

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Again, that's drinkelement.com/huberman to claim a free sample pack. Now, with respect to everything we've talked about about sun exposure, sunscreen, and skin cancer, I'd be remiss if I didn't discuss a study that's often used kind of as a wedge or a weapon in the online debates about sun exposure, skin cancer, and mortality.

And the title of this study is quote, "Avoidance of sun exposure as a risk factor." That's right, sun exposure as a risk factor "for major causes of death, a competing risk analysis "of the melanoma in Southern Sweden cohort." So the basic design of this study was to evaluate people's self-reported amount of sun exposure across many years, and then to correlate that with all-cause mortality, and then to relate it to different causes of disease, in particular, cardiovascular death, compare this to smokers.

Keep in mind that some of the people who were reporting their sun exposure were smokers, some weren't. And the conclusion of this study that drew a lot of attention and continues to draw a lot of attention is the following. Quote, and here I quote from the abstract, "Non-smokers who avoided sun exposure "had a life expectancy similar to smokers "in the highest sun exposure group." Okay, I'm going to repeat that.

"Non-smokers who avoided sun exposure "had a life expectancy similar to smokers "in the highest sun exposure group." So what many people take this to conclude is that avoiding sun exposure is as dangerous as smoking, okay? That's not the conclusion that I'd like you to take away, because what this study basically shows is, and here I continue, quote, "Compared to the highest sun exposure group, "life expectancy of avoiders of sun exposure "was reduced by 0.6 to 2.1 years." So you go, wait a second.

Can this really be true, that people that are avoiding sun exposure have a lower life expectancy than people who get sun exposure? And indeed, in this particular study, that does seem to be the case, but the interpretation of this is not completely straightforward. Here's what we know. Getting some degree of sun exposure appears to be good for life expectancy.

That is true. But is it directly related to sun exposure? That's a critical question. And is the increased sun exposure that one gets, if you do get sun exposure, linked to other issues, in particular, the development of melanoma? As you recall, melanoma was even in the title of the study.

So here's how I think we should think about this study. It does appear that getting sun exposure is correlated with longer life expectancy, but there could be any number of different reasons for that. For instance, people that are getting regular sun exposure, presumably, are also enhancing activation of the vitamin D pathways, which is related to any number of different things.

They, no doubt, are experiencing increased feelings of well-being. I talked about papers that have substantiated that earlier. And frankly, we didn't even need a scientific study to substantiate that, although it's always great to have it. We know that being out in sunshine for some period of time each day, as long as we don't get burned in the sun, feels good.

Why does it feel good? It leads to the production of testosterone, estrogen, some of the endorphins that generally make us feel good. It is directly related to the pathways associated with dopamine release. There's a whole story there about seasonality, both in humans and other animals, about dopamine synthesis. When we get sunlight, there's elevated dopamine and serotonin and testosterone and estrogen and feelings of well-being and libido.

This is all well-substantiated in animal models and humans. So getting sun exposure makes people feel good. When people feel good, they tend to be lower stress. When people are feeling good and they have energy, because there indeed is a direct relationship between sun exposure, especially to the eyes early in the day, and our feelings of elevated mood and alertness and energy, they tend to exercise more, walk more.

And of course, if you're outside exercising more, walking more, cycling, swimming, you're also going to get more sun exposure. And we know that exercise is strongly related to improved or extended life expectancy. Okay, so the study basically says getting sunlight as opposed to very little sunlight is good for life expectancy, but it doesn't say get too much sunlight, right?

Because, and this is interesting, it is very clear that the people who lived longer because they were getting more sunlight also tended to have more cancers, including melanoma. But this is a very important point. It's also the case that the longer one lives, the more likely you are to develop a cancer, okay?

So as you can see, these studies that many people just draw one straightforward conclusion from, such as people who get less sun exposure don't live as long as people to get more sun exposure. Well, that's true. But when you get more sun exposure, very likely you're doing other things like exercise and feeling better that relate to living longer.

So it's very difficult, if not impossible to isolate one single variable, in this case, sun exposure as the key variable. However, I'm happy to go on record saying that we know from so many studies of animal models and humans that sun exposure, especially early day sun exposure, when the sun is low in the sky to set your circadian rhythm and late day sun exposure, okay?

I'm not talking about middle of the day, getting baked in the sun and sunburned or things of that sort. But around the time of sunset, especially sun exposure to the eyes, is powerfully modulating your circadian rhythm to elevate daytime mood focus and alertness and improve sleep. Both of which are strongly correlated with improvements in mental health, immune system function, feelings of wellbeing, enhanced cognition.

I mean, there's this whole story about people with Alzheimer's and disruptions in circadian rhythms and sleep. So sun exposure to the eyes in terms of setting circadian rhythm, powerful. Powerful improvement of life expectancy and immediate health. Sun exposure to the skin, no doubt, very powerful positive modulators of certain hormone and neuromodulator pathways such as dopamine, testosterone, estrogen, and so forth that make people feel good and do things generally that are good for them.

Okay, generally, not all the things people do with elevated dopamine, testosterone, and estrogen are good for them. We know that for sure. But getting some sunlight, that is some appropriate dosage of sunlight, especially to the eyes early in the day. Don't stare at the sun, don't damage your eyes, but getting some of that sun exposure to your eyes early in the day and some to the skin, especially in the early and later part of the day, clearly is positively correlated with various health metrics in terms of mental health and physical health and not surprisingly with lifespan.

So I mentioned the study 'cause I do think it's very interesting, right? I think it's really interesting that people who completely avoid sunlight are not living as long as people who get some sun exposure. And some of this actually is on par with what's experienced with cigarette smoking. I think something that everyone agrees is negative in terms of life expectancy and certainly is not good for a great number of different systems within the brain and body.

But I think the study sometimes is used to highlight the wrong conclusion, which is that sunlight itself is extending lifespan. I think that that very simple conclusion can be taken too far and can start to negate some of the equally important messages about excessive sunlight exposure causing certain problems as it relates to skin cancers, which we talked about earlier, as it relates to things that you can do in order to offset some of that risk with, if I were to suggest, a physical barrier if you need it, a chemical-based sunscreen if you choose to use sunscreen.

And of course, that's an independent choice that each of us have to make for ourselves. Okay, let's talk about youthfulness of skin or the appearance of youthfulness in skin. Before I did this episode, I put the call out on social media for questions about skin and skin health. And I must say that the vast majority of questions related to this topic.

And it's a very interesting one because it relates to a lot of decisions that people are making about what to do, what to buy or not buy as the case may be. And it is an enormous, probably hundreds of billions of dollars industry, if not trillion dollar industry over time, this business of devices, products and procedures to try and reverse aging or the appearance of aging in skin, or even create de novo, new synthesis of collagen in skin and other things to make skin look more youthful.

Okay, so if we step back from this whole area, we have to ask ourselves, what do we know for sure about what makes skin look youthful and what can be done to make skin look more youthful? And to understand the answers to those questions, we simply have to go back to the beginning of today's discussion for just a moment.

Remember that we have the epidermal layer of skin, we have the dermal layer of skin, we have the vasculature, the blood vessels and capillaries, you have the nerve inputs there, and you have a bunch of different cell types in there, the keratinocytes. You have different proteins within those cells like collagen, elastin that over time can, yes, be mutated by things like UV rays from the sun, but that over time tend to lose their elasticity, which leads to wrinkles and sagging skin.

You also have this issue of hydration of the skin, right? Skin has a lot of watery components within it, actual water within it. And those watery components are what give it its kind of plump, moist look, smooth look, as opposed to desiccated, sagging, wrinkled look, to speak in extremes.

And there are hundreds, if not thousands of different chemicals out there that dermatologists, as well as cosmetic surgeons, as well as just, frankly, manufacturers of products, assert are going to be good for skin. So let's talk about where there is a lot of evidence for certain things that you can do if your goal is to increase the youthfulness or the appearance of youthfulness in your skin.

And one of the main ones is collagen itself. And now I have to admit, I was very surprised when I looked at this literature, but I was positively surprised. Here's why. As you know, there are various macronutrients present in foods. You can have proteins, fats, and carbohydrates. When we ingest proteins, such as beef, chicken, fish, eggs, as well as some vegan sources of proteins, like beans, or lentils, or tofu, or things of that sort, they contain different amounts of different essential amino acids.

And those essential amino acids and other amino acids are used as the building blocks for proteins in our muscles, in our tendons, in essentially all the organ systems of our body. The lipids are also used for cell membranes, et cetera, okay? This has been discussed various times on this podcast before, people like Dr.

Lane Norton, Dr. Gabrielle Lyon, and others. It's well-established that when these proteins are broken down in the gut, some of those amino acids go and serve for the purpose of tissue repair. Others are for the purpose of other things. What most people in the field of nutrition agree upon, and what certainly I believe, is that if you were to, say, eat a little bit of liver, right, you might have a little bit of cooked liver, or a little bit of skeletal muscle in the form of like a steak, that there's no selective trafficking of the amino acids that are broken down from the liver that you eat to your liver, right?

So when you hear that eating liver supports your liver, it may do that by the broad process of certain amino acids and vitamins and lipids, et cetera, serving your liver and other organ and tissue systems of the body, but not selectively your liver. However, when we talk about collagen, this protein that forms one of the most essential aspects of what makes our skin what it is, which is elastic, and to have some tensile strength where you can push on it, it returns to its original position, especially if it's well-hydrated.

And makes our skin very youthful in appearance when we're young, and then as it degrades when we get old, makes it look less youthful, wrinkles and sagging and so forth. Well, then why would eating collagen protein, which can come from any number of different sources, it can come from fish sources, it can come from, believe it or not, animal health sources, can come from any number of different sources, tendon, et cetera, why would ingesting collagen be selectively trafficked to the collagen in our skin, right?

That doesn't square with everything we know, and yet, when you look at studies, including meta-analyses of studies where people supplement with collagen powders, and these powders typically come from fish or tendon, any number of different sources, when people do this, and then measures are taken as to skin appearance, skin elasticity, there are a bunch of measures that can be done in humans in the laboratory to do this, you often will find studies that show statistically significant improvements in collagen composition and skin appearance, and even the appearance of reduction in wrinkles and so forth.

So this is an interesting exception where the ingestion of a particular protein that naturally exists in abundance in certain tissues, such as skin, but also other tissues, like tendon, ligaments, et cetera, seems to be assisting in either the repair and rejuvenation of collagen, or perhaps some other aspect of collagen synthesis that leads to improvements in collagen composition and the appearance of skin in humans.

That's very interesting, and the study that I find particularly interesting is one that I'll link to in the show note captions, it's entitled, quote, "Exploring the Impact of Hydrolyzed Collagen "Oral Supplementation on Skin Rejuvenation, "A Systematic Review and Meta-Analysis." And the basic takeaway of this and other meta-analyses, and the studies within this meta-analyses, is that when people supplement with anywhere from five to 15 grams, okay, grams, of hydrolyzed collagen per day, in particular in combination with vitamin C, it doesn't have to be a lot of vitamin C, that one can observe, okay, not always, but can observe some visible improvements in skin composition, meaning less wrinkles, even some reversal of wrinkles, less skin sagging, more youthful appearance, more kind of, let's just call it rebound elasticity of the skin.

I realize that's not the appropriate technical term, but the ability of a skin to bounce back from an indentation when you push down on it, as opposed to saying down or sagging. So some pretty impressive results when one considers that what people are basically doing here is just mixing up some hydrolyzed collagen protein, and then drinking that down once per day or so.

Now, that is not to say that you have to supplement with hydrolyzed collagen, why? Well, collagen is also present in various foods. So for instance, drinking bone broth, beef bone broth, chicken bone broth is a rich source of collagen. You can go online and simply look up, just by web search, you can just say what foods contain high levels of collagen, and you'll get a list of things back there.

Hopefully a few of those are not just palatable to you, but you actually like, and you can start to include those in your daily diet, or you could supplement with hydrolyzed collagen protein. There are any number of different sources for these. It's interesting that while indeed I don't believe, and there is frankly zero evidence for selective trafficking of amino acids arising from a particular organ source to that particular organ when you ingest it, it is interesting that consuming hydrolyzed collagen in the form of a supplement or deriving it from foods like bone broth, et cetera, does seem to be able to improve collagen synthesis or the appearance of skin, making it more youthful.

For those of you that are interested in ingesting collagen peptides as a way to improve the youthfulness of your skin, should mention that the dosages there come in a range, depending on the studies that you've looked at. And the dermatologist that I spoke to said, if one decides to go down this route of supplementing or getting collagen from food sources, you want to aim for anywhere from 15 grams to 30 grams of collagen peptides per day, okay?

That's a bit higher than what was used in a number of studies, but you'll find studies that use 30 grams. And that that whole process can be augmented, can be improved through ingestion of 500 to a thousand milligrams of vitamin C as well. But check the label on those collagen peptides that you might be supplementing with, 'cause oftentimes they already include that 500 to a thousand milligrams of vitamin C.

I should also mention that the dermatologist I spoke to said that they like collagen protein supplementation, not just for the reasons discussed up until now, but that they liked them for a number of other reasons, such as the potential anti-inflammatory effects of collagen proteins. To be honest, I don't know what the exact mechanism of that is.

Maybe if you get a certain protein threshold, the inflammation is down. But anyway, that's still cryptic to me. But in any case, they did describe some of the potential mechanisms by which collagen ingestion can do its thing in terms of improving youthfulness. It's broken down in the blood into dipeptides and tripeptides, which then are used within the collagen itself of the skin.

This is the hypothesis. And that it can increase the chemotaxis, the mobility of fibroblasts, which make up some of the skin tissue and give rise to the appearance of more youthful skin. There's also evidence that ingestion of hydrolyzed collagen peptides can improve the elasticity of the skin barrier on the outside, right?

Make it look nice and taut. If I guess we say nice, we're sort of passing subjective readout on this. Make it appear taut through the increase of certain proteins unrelated to collagen, such as filigrenes, elastins, et cetera. What about other peptides? Okay, so this is a big topic nowadays, especially in the online communities.

I did an entire episode of this podcast about peptides. Keep in mind that insulin is a peptide. Ozempic, what is essentially an agonist for glucagon-like peptide one. This is a very popular prescription drug now for the treatment of obesity and for the treatment of diabetes. There are lots of things that qualify as peptides.

A peptide is simply a small chain of amino acids. A polypeptide is a bit longer chain of amino acids. And then proteins are made up of amino acids. Okay, so when we say peptides, that means many, many things. But these days, when you hear about quote-unquote peptides, especially in online communities, generally people are referring to exogenously given, okay?

So pills, ointments, or more typically injections of peptides that are designed to achieve some specific biological or physiological outcome. And one of the more common of these peptides being used nowadays is one that I've talked about before called BPC-157, Body Protection Compound 157, which is essentially a synthetic version of something found in gastric juice in all of us.

It's known that certain peptides within the gut that BPC-157 is known to mimic, or it actually is a synthetic version of that exact sequence or a portion of that sequence, can assist in tissue and wound repair of different kinds. Tendon, anything involving fibroblasts, all of that has been well-demonstrated in vitro in a dish, okay, so not in vivo, as well as in vivo in certain cases, but only in animal models.

To my knowledge, there's only one study, and frankly, it's not a very good study at all, on BPC-157 in humans, and yet a lot of people are taking BPC-157 either orally in the form of a capsule or pill, or more typically injecting it. What does it do, or what does it likely do in humans?

We know from animal models that BPC-157 increases angiogenesis, the growth of capillaries and blood vessels. We know this. It can accelerate wound healing by virtue of increasing fibroblast motility. For this reason, it's used post-injury in sports. It's used by people who want to build more muscle. It's used by endurance athletes.

It's used for cosmetic purposes. Anytime people are using BPC-157, for any of those purposes, it's likely that they're using it in part to increase the blood flow that's available to a given tissue and the repair of that tissue. Now, again, I do want to caution people that there is very little, basically no evidence in humans besides the anecdotal evidence that people say they healed faster.

What I do know is that anytime you get vascularization of tissue, you're going to get improved blood flow, so it all makes sense mechanistically. I also know that vascularization due to BPC-157, even if it's injected locally into a given tissue, is likely to occur globally throughout the body. This is why some people taking oral BPC-157 or injecting it just subcutaneously at the level of their stomach, a little bit under the skin at the level of their stomach, report faster wound healing even in a distal limb or like a hand or a nerve injury in their foot or something like that.

That also tells us that there's going to be increased vascularization of other tissues, such as skin, such as tumors, if tumors exist. So you need to be very careful. I need to say that upfront as a cautionary note because it is very clear that many people are starting to either inject BPC-157 or apply it in the form of a topical cream in effort to get more vascularization of skin in order to make that skin appear more youthful.

And more and more products are out there that contain BPC-157. I can't in good conscious recommend those products. I can only offer to you the likely mechanism by which they work if they work, and also offer you the caveat that it is unclear that BPC-157 can go transdermally if it's applied topically.

So if you put it on a, say, wrinkly portion of your face, so like I've got crow's feet. Crow's feet come from either aging, smiling, or both. You know, the crow's feet are the kind of wrinkles that extend out the corners of your eyes when you smile, or for me, 'cause I'm, you know, 48, you know, and probably do that even when I don't smile.

The logic would be that if you take a cream containing BPC-157 and you put it on there, that you'll get increased vascularization of that area, delivery of more growth factors and nutrients, and those wrinkles will either be halted in their aging progression or that they will reverse. That's the logic.

To my knowledge, there are no clinical studies, and I'd love to know from you, if you've tried these products, please put your experience of those in the comments on YouTube, so we can get a sense of whether or not people are having good results with this. That, of course, is not a controlled study, but I'm very curious as to know.

Many of the products that contain BPC-157, by the way, also contain copper. Copper is a trace mineral. It's found in your diet. There is some evidence that copper is important for some of the collagen and other elements of skin synthesis pathways. And so the mechanistic logic and the biochemical logic is there on paper.

However, it's also clear that ingesting too much copper can induce an inflammatory response and would lead to the exact opposite desired effect that people who are using copper and usually copper BPC-containing products are taking them for, which is to halt or reverse the appearance of aging in their skin.

Why am I going through this whole gymnastics of, you know, BPC-157 and copper? Well, because nowadays many, many products are starting to include "peptides" for skin rejuvenation. And most often those peptides are of the copper variety, of the BPC-157 variety, and oftentimes also with things related to collagen synthesis, sometimes collagen directly.

So you'll find oral products that one takes by pill form that are BPC-157, copper, and collagen, or things that promote synthesis of collagen. You'll find ointments that are pure BPC-157, still unclear if those go transdermal. Okay, so this is still a very, very young science. And most of this is not being explored in randomized control trials.

However, I know some of you out there are pretty experimental. You like experimenting with this kind of stuff. You like hearing what's working for other people. Here's what I suggest. If a sunscreen or a lotion or a pill or an injection is asserted to contain peptides to help with skin rejuvenation, make sure you look and see which specific peptides are included.

Know the risks associated with BPC-157. It's uncertain risk about acceleration of tumor growth, but the mechanistic logic is just as strong for that with BPC-157 as it is for BPC-157, encouraging vascularization of any other tissue, muscle, tendon, ligament, or skin for that matter. So I'm not telling you what to do, just know what you're doing and understand the likely mechanisms behind it in the absence of any of these randomized control trials.

I will say in service to making sure that your diet and or supplementation includes enough trace mineral copper. Copper has been shown to play a key role in DNA repair, which is a critical component of the turnover of collagen and other proteins in skin. It has been shown to reduce so-called reactive oxygen species.

So it serves as a so-called antioxidant and this relates to what I just said, reduced inflammation, but too much copper is a problem. So I wouldn't run out and start supplementing with excessive amounts of copper. Please don't do that. But you want to make sure that you're getting sufficient amounts of copper from your diet and you can simply look up online what sufficient amounts of copper are given it's a trace mineral.

And it's very likely that if you ingest any kind of supplement that is a multivitamin mineral supplement or a foundational nutrition supplement, that includes at least some copper. So it's likely that you're sort of quote unquote topped off in terms of the amount of copper that you need, but very unlikely to be excessive amounts of copper.

But if you start supplementing with copper beyond that, again, you can induce an inflammatory response. So it's a dosage kind of middle ground issue there. You don't want your copper too low. You don't want your copper too high. You want it right there in the middle. Okay, as I mentioned before, we will talk about other components of food that are great for skin health.

And we will also talk about components of certain foods like advanced glycation end products. I don't know if you've heard of those before, but very interesting, not good stuff that you want to avoid if you can, especially if your concern is youthful looking skin and healthy skin and frankly health overall.

But before we do that, I think it's worth paying attention to a few things that you can potentially take that can really improve the youthfulness of your skin for which there is excellent science to support it. Okay, so when I spoke to board certified dermatologists who trained at excellent institutions, what people can do to improve the youthfulness or the appearance of youthfulness in their skin and that there specifically be peer reviewed studies to support their statements.

They mentioned hydrolyzed collagen protein in combination with vitamin C. We talked about that earlier. They mentioned a bunch of do's and don'ts as it relates to sun exposure and nutrition, et cetera, some of which we've covered, some of which we are yet to cover, but will soon. And they mentioned supplementing with niacinamide.

Niacinamide is a form of vitamin B3. It is also sometimes referred to as nicotinamide. And I was told that when taken at twice per day at a dosage of 500 milligrams per dose for a total of one gram or 1000 milligrams per day, that niacinamide supplementation can increase the production of ceramides, which relate to the lipids in skin that improve the moisture in skin.

And by the way, moisture in skin is a key component of the youthfulness or plump appearance of that skin. And when I say plump, I don't necessarily mean outwardly rounded plump. I mean, the fact that the skin looks like the outermost layer of the skin, which you now know as the epidermis, is kind of taut and the skin looks hydrated and smooth at the level of its outer appearance, all of that is improved by niacinamide supplementation, but that the supplementation has to be carried out for three to six months or more before that effect is noticed.

Now, the origin of the niacinamide effect on the youthfulness of skin could also be related to the fact that there's evidence that niacinamide supplementation can reduce inflammation of skin overall. We haven't talked so much about the immune skin relationship, although as I alluded to at the beginning of the episode, this is a key relationship.

But for those of you suffering from rosacea, from acne, so rosacea being a reddening of the skin, we're going to talk more about it later and specific things that can be done for it. Acne almost always involves some reddening, often painful reddening of specific pox on the skin, sometimes even the appearance of, you know, pus-filled bumps, this sort of thing, that niacinamide supplementation may also assist there because of the reduction in inflammation.

And we'll talk all about the relationship between inflammation and acne. Regardless of whether or not you suffer from rosacea or acne or not at all, that niacinamide supplementation may benefit you. Also because niacinamide supplementation appears to balance the level of oil production in the skin, you need oil in the skin, you need oil down in those pores, but not too much.

And that it can definitely help reduce the appearance of clogged pores. And if you're concerned about pores that appear too large, this typically happens in the face, around the nose, on the upper cheeks, although other regions of the body as well, niacinamide supplementation may assist with that as well.

There's also a number of people out there that are concerned with specific spots that they see as hyperpigmented spots. So regardless of whether or not overall your skin is very light or very heavily pigmented, supplementation with niacinamide can reduce the appearance of accumulation and maybe even the actual accumulation of melanin in a particular spot, so-called dark pigmented spots, that some people decide that they don't want for whatever reason, usually just cosmetic reasons.

Although there may be reasons why hyperpigmentation in a given area could relate to skin cancers. We talked about that earlier. Another reason to go get not just your moles, but all of your skin checked at least once per year. Now, if you decide to supplement with niacinamide, you have the option of either taking that 1,000 milligrams and two 500 milligram dosages per day.

You also have the option of using any number of different topical niacinamide ointments or serums that exist out there. Keep in mind that many skincare products already contain niacinamide, so check the label. And there, the dermatologists tell me that to be effective, the niacinamide needs to be present at at least a two and as high as 10% concentration within those ointments or serums.

Keep in mind that many serums and ointments also contain what's called hyaluronic acid. Hyaluronic acid is a natural component of the skin that provides a physical substrate for holding in water, so moisture within the skin. It does a bunch of other important things too within the extracellular matrix and elsewhere, the regions between the cells that is.

And supplementation with hyaluronic acid or ointments or serums that contain hyaluronic acid and niacinamide are pretty common out there because of the already stated effects of niacinamide and the fact that hyaluronic acid can serve as what's called a humectant, something that serves to sort of barrier in moisture at the level of the skin, okay?

So it gives that kind of plumping moist look of skin that's characteristic of youthful skin as opposed to aged skin. The dermatologists and the cosmetic surgeons that work on faces that I spoke to, I told you I consulted with a fairly large and diversified group of folks in preparation for this episode, all agreed that supplementation with collagen, vitamin C, niacinamide and hyaluronic acid was something that they suggest to their patients.

The other supplement, well, actually it's a prescription treatment most often that dermatologists recommend if the goal is youthful appearing skin, are things within the so-called retinoid pathway such as retinol, okay? Many of you have perhaps heard of this and it's a whole story related to the relationship between vitamin A and skin.

Okay, so tretinoin is the common name for it, although some of you may know it as retin-A and prescription drugs that are similar to that are basically derivatives of vitamin A, why? Why are these used for skincare? Why are they used to increase the youthfulness of skin? Well, vitamin A gets into skin cells and is converted into something called retinaldehyde, then into something called retinoic acid.

Now, very important to know that retinoic acid is involved in a lot of different cellular processes, especially during neural development. This is why, and please pay careful attention to this, this is why women who are pregnant or breastfeeding should avoid taking these products because it can seriously disrupt the development of the fetus, okay?

And keep in mind that many times people don't realize they're pregnant for some period of time, so this is of paramount concern, okay? We could have a whole discussion as to the role of retinoic acid in fetal development, but you don't want to tamper with that pathway, okay? Very serious consequences can occur.

Okay, so when retinoic acid gets into cells, it can activate what's called transcription factors. Transcription factors bind to DNA, okay, your genetic code, and can induce the transcription and translation of DNA into RNA and RNA into proteins of particular types. So think of transcription factors as sort of setting a menu of different proteins that ultimately will be formed, okay?

By binding to DNA, and then you get DNA to RNA, RNA to protein, and you're getting a set of proteins related to a particular process. That's generally how transcription factors work. And retin-A, tretinoin, and things similar to that are going to induce the formation of collagen protein within skin, as well as other proteins that relate to the formation of de novo skin, new skin, and can replace old degenerated skin.

So the dermatologists that I spoke to were really bullish about the fact that, believe it or not, they felt that people starting in their 20s could very well, as long as they're not pregnant or lactating or planning to get pregnant, could take retin-A or things similar to it in order to stimulate the production of more skin and look more youthful.

Now, for people already in their 20s, you know, by my read, they're already youthful, but that they could initiate the use of these compounds, at least in one's 20s and continuing on, really, as long as they wanted through life. And they told me about, quote, "remarkable results." So I said, well, why isn't everyone aware of this?

Why isn't everyone taking them? Well, it turns out that these different compounds can also increase sensitivity to light, make you more prone to sunburn, to some of the other effects of light on skin, even from screens or from artificial lights. So one has to be careful about inducing too much skin sensitivity to light of all kinds, not just sunlight, that they can also induce some redness or dryness.

So one has to get the dosage right, the frequency of use right, and they can be a little bit tricky to work with, but that if one can home in on the right dosages, the right frequency, et cetera, the dermatologists felt like this was one of the best things that one could do to improve the youthfulness or the appearance of youthfulness in one's skin.

Now, I find this interesting for a number of reasons. First of all, I've heard of Retin-A, right? I've heard of these compounds before, but I hadn't heard about all these, you know, reportedly spectacular things like improved angiogenesis, vascularization of the skin. This is why people are taking the rather experimental, untested BPC-157 that I talked about before, the improved elasticity of skin, which somehow seems related to the ability of these compounds to remove degenerated elastin within the skin, to clear that out, as well as to induce de novo synthesis, and even the number of different fibroblasts that are present in skin.

So more new skin, clearing away of old skin, improved vascularization. And while all of this sounds a little bit too good to be true, the mechanisms by which it's asserted to work all hold up. So that's always reassuring, right? Mechanism isn't everything, but it's really nice to see there.

For instance, these compounds are known to get into the nucleus of cells, right? To impact gene expression. We talked about that before. You have receptors on the surface of cells. Okay, so cell surface receptors. You also have nuclear receptors. And the ability of certain things, we call them ligands, but these are chemicals, right?

In this case, you know, in the vitamin A pathway to get into the nucleus of cells and impact gene expression. This is actually how hormones like testosterone and estrogen change the way that people look so dramatically during puberty. They actually, you know, they operate by binding to cell surface receptors.

They also get into the nuclear compartment of the cell. They bind to nuclear receptors and they turn on entire genetic programs that cause, for instance, deepening of the voice or the growth of hair or breast tissue, et cetera. So these are powerful compounds. Now I talked to a cosmetic surgeon expert in face specifically.

Remember, cosmetic surgery is done for a number of different areas of the body, but for face specifically, who also specializes in these sorts of treatments for skin. And they've started using, and are frankly quite confident in, the use of retinoid esters that can be applied to the surface of the skin.

These things are available not by prescription. There's far less research on these sorts of compounds, but these compounds get enough positive support from the people that have tried them, reporting improved youthfulness of skin, et cetera, that some of them are becoming quite sought after and people, let's just say, are very enthusiastic about them.

And I will say that in discussing the various mechanisms of this with these cosmetic surgeons and some dermatologists, the logic holds up. So you're starting to see more and more of these. Now, as I mentioned at the beginning of today's episode, there is zero business relationship between me, the podcast, or any of these people that have marketed serums or creams or prescription drugs for that matter, related to skin health and skincare.

However, I have provided a couple of links in the show note captions of some of the different sources of these. Obviously, if you need a prescription for something like tretinoin or something similar, because you're interested in this whole retinol, retin-A, vitamin A pathway story, you need to talk to a board-certified dermatologist who could potentially prescribe that for you if they decide it's right for you.

But in terms of these topical ointments and serums and creams and things like that, I do provide a link to at least one source of those that uses the retinoid ester. Just keep in mind that these various ointments and serums do not yet have the randomized control trials to support them that some of the other compounds that we were discussing do have.

Now, I'd like to talk about things that one can do to improve the health and appearance of one's skin that don't involve taking anything or putting on any kind of ointment or serum or anything like that. And what I'm referring to is phototherapy. Now, at the earlier part of the episode, I talked about how different wavelengths of light, like UV light and long wavelength light can penetrate skin to different depths and some of the negative, but also positive things that that can do.

So for instance, we talked about UV light mutating DNA in cells and potentially causing cancers, accelerating the aging process and so forth. But as you also recall, long wavelength light, so-called red light and near infrared light, which is even longer wavelengths of light can penetrate deep into the skin tissue.

So pass that outer epidermal layer into the dermal layers of the skin and can access the vasculature, the neurons, some of the glands located deeper in the skin. And of course, the cells there, like cells in the epidermis, I should point out, contain things like mitochondria for which red light has been shown to be beneficial.

Why? Red light and near infrared light phototherapy has been shown to reduce reactive oxygen species and thereby to improve mitochondrial function in cells. And that in turn has been shown to be beneficial for all the different processes within cells that involve mitochondria, which of course include energy production, but a bunch of other things too.

So when I say that phototherapy has been shown to be beneficial for cells of the body, it's not just cells of the skin. In fact, a Nobel prize was granted in the early 1900s for the use of phototherapy for the treatment of lupus. So this is not a new technology.

At the same time, while there are many studies exploring the use of phototherapy for improvement of skin health and appearance, most of those studies have fairly low sample sizes, but there are a lot of those studies. And fortunately by now, there are a few meta-analyses and reviews that take into account lots of different studies using slightly different wavelengths of light applied to different portions of the face for different purposes, treatment of acne, maybe even putting red light near infrared light on one half of the face to have a so-called within person control to compare the changes in skin or lack of changes in skin as the case may be between one side of the face and the other.

I'll put links to some of these studies and some of the meta-analyses and reviews of these studies. One that I like in particular was published in 2018 entitled "Light Emitting Diodes in Dermatology, A Systematic Review of Randomized Controlled Trials." Of course, randomized controlled trials being one very powerful way to analyze the utility of a practice or a compound.

It's not the only way to assess the utility of something. I know some people argue that they are very useful, but keep in mind in the field of medicine, we often have entire fields or even entire chapters of medical books that are based on case studies. For instance, we implicate the so-called hippocampus of the brain for its function in human memory, which it absolutely has.

And that fact largely grew from one major case study that then exploded into a number of different animal model and then human studies later on. So we all love randomized controlled trials, reviews of randomized controlled trials and the uses of their phototherapy for treatment of skin conditions and improving the quality of skin are wonderful and point to the fact that phototherapy can indeed improve the appearance of skin in conditions like acne, can accelerate wound healing, can improve the youthfulness appearance of skin, but these effects tend to be somewhat mild to moderate when they occur.

And certainly there are many studies that show no significant effect, no statistically significant effect. That said, I'm of the belief based on my read of the literature, and this is a literature I've spent a lot of time with, frankly, because I did an episode all about light and health.

I've also been very interested in the use of phototherapy for the treatment of eye diseases and offsetting age-related decline in visual function. There's some interesting evidence there. Again, mild to moderate effects, but that can be meaningful in the real world. And when I step back from all of the literature, here's what I see.

And this is what I ran by a dermatologist to make sure that they thought that this protocol would be useful or not useful, right? I asked them, I didn't tell them, do you think this will be useful? Tell me yes, I asked them. And what we basically converged on was that if somebody decides to do phototherapy, the use of phototherapy that involves long wavelengths of light, so red light plus near infrared light, typically, at a distance of about a foot to two feet from the light source, depending on the intensity of the light source, although that doesn't seem to be so critical, but one can't be across the room from the red light source, nor should one get right up next to the red light source so that there's a lot of heat generated from the red light source that one can feel.

But at a distance of about a foot to two feet away at fairly high intensities, done for anywhere from 10 to 15 minutes, five to seven days per week on a consistent basis, does seem on average to lead to improvements in the youthfulness appearance of skin. Why this would be the case isn't exactly clear, but there are a number of different logical interpretations such as reduced inflammation, improved mitochondrial function, all downstream of reduced reactive oxygen species, improved blood flow to that particular area because of the effect that long wavelength light can have on vasodilation, sort of expansion as opposed to contraction of blood vessels and capillaries.

All of this makes mechanistic logical sense, and the effects that one sees in these various peer-reviewed papers, randomized controlled trials, seem pretty good, meaning they are mild to moderate. None of them are sort of jaw-dropping, like, wow, complete reversal of severe acne or massively accelerated wound healing. And we also, of course, have to take into account that many people who are doing phototherapy often are combining it with other things, sometimes in today's era, like injections of BPC-157 or the use of hyaluronic acid or niacinamide, et cetera.

So these things aren't always being examined in isolation, but when we look at this literature, I think it's fair to say that there is now substantial evidence for the use of phototherapy for improving the quality of skin, and in some cases for reducing the symptoms of acne, reducing the symptoms of psoriasis, basically any condition where improved blood flow, lowered inflammation, fewer or reduced oxygen species, improved mitochondrial function, delivery of nutrients, anytime some or all of those things are gonna be involved, phototherapy makes logical sense, and so it's no surprise that we're seeing increased evidence for phototherapy in these conditions.

Now, I've provided a link to the review of the randomized controlled trials that I mentioned a bit ago. I also provided a few links to some specific studies that show pictures of before and after, in some cases on two sides of the very same face. I did an entire episode about light and health.

I'll also provide a link to that episode, and if you don't wanna listen to or watch that entire episode, you can go to specific timestamps in that episode to learn about the uses of phototherapy for the treatment of skin, eye, and other conditions related to mental health and physical health.

Now, keep in mind that when people hear phototherapy, they almost immediately think about a device, and that makes sense, right? Red light, near-infrared light. However, if you recall, there's this thing called the sun that emits a full-spectrum light, which of course includes red light and longer wavelengths of light, okay?

So just 'cause you can't see those longer wavelengths of light, that doesn't mean they're not there, just like UV light. You can't sense UV light with your eyes. By the way, ground squirrels and some other animals can. It's thought to be the case that they have photoreceptors to detect UV because they actually, this is sort of strange but interesting, you'll never forget this, that they'll take their urine and they'll spread it on their stomach with their little paws and they'll stand up and they'll like signal flash one another from across the prairie or whatever it is or across the lawn to signal to one another.

So they're sending UVP signals across the lawn. I'm not making this up. I actually studied a little bit of this when I was an undergraduate, but not at the level of the urine and the signaling, at the level of the retina. Any discussion about skin has to include a discussion about nutrition.

Why? Well, remember the fact that I mentioned at the beginning of today's episode that your skin and your immune system have a very intimate relationship. It's bi-directional. Your skin reflects the status of your immune system in many ways. And this is why many people with autoimmune conditions, things like lichen planus, you can look it up, or if you mind particularly striking photographs, please don't look it up.

But people that have autoimmune conditions that often manifest in skin conditions. We'll talk more about this in the context of psoriasis in a little bit. But anytime we're talking about the immune system or skin, we need to take into account the gut microbiome and nutrition. So many people asked, what are the things that they should eat to have healthy appearing youthful skin?

They also asked, what are the things that one eats that could exacerbate things like acne? And what can one eat in order to reduce their acne? So let's just start off with the basics. And here I'm going to be fairly brief because I think we all know the big take-home message about nutrition nowadays.

We hear over and over again, and we should pay attention to the fact that the vast majority of our food, well, I should say, if one desires to be healthy, mentally healthy, physically healthy, and a high-performing individual in any number of different things, cognitive, physical, or otherwise, we want to consume the vast majority of our foods from non-processed or minimally processed sources, so-called whole foods.

So fruits, vegetables, if that's within your diet, some people include grains, some people don't. I'm not here to discuss that. Meat, eggs, fish, chicken, and so forth, if that's within your diet plan or your nutrition, or if you're a vegetarian or vegan, you make the associated adjustments so that you can make sure you're getting enough protein and amino acids, but it's in keeping with your ethical and maybe your health goals, okay?

So we're not here to discuss vegan, vegetarian, omnivore, of which I am, or carnivore, okay? That's not the discussion. I think all of those groups agree that getting the majority of your nutrition from non-processed or minimally processed foods is going to be best, and that, of course, if you're human, sometimes you'll ingest processed foods, but really trying to avoid highly processed foods is critical.

Now, with respect to the specific foods that can improve skin appearance and skin health, it's very clear that diets that are of the so-called low-inflammatory type, that don't spark inflammation, so these would be things that sometimes are referred to as the Mediterranean diet or a paleo-like diet. You hear these terms, but what are we really talking about?

Mostly whole foods, minimally processed foods, okay? And then there's variation depending on whether or not you emphasize or de-emphasize meat and fish or emphasize or de-emphasize vegetables, this kind of thing. Again, I'm an omnivore. I love fruit. I love vegetables. I do like rice, oatmeal, and some pastas. I like a great sourdough bread.

I like butter. I like olive oil. I like meat. I like fish. I think I am representative of most people out there because I eat most all those things, but I also eat the occasional croissant. I also eat the occasional slice of pizza. I don't eat a lot of that stuff, but I eat it now and again.

And then of course you have people that are super strict. What do we know about the relationship between specific foods and skin health and skin appearance? Well, anti-inflammatory diet, we've more or less spelled out what that represents without getting into too many specifics. And then there are the specific components within foods.

So vitamins, minerals, and micronutrients, as well as things like collagen present in bone broth that can be really useful to include. So one of the, I think, best accounts on dermatologic health and skin health and appearance on the internet is Dr. Andrea Suarez. She's a medical doctor, board-certified dermatologist, and she has a wonderful video that describes the various foods that one can eat to promote skin health and skin appearance.

And rather than repeat that entire video, because A, that wouldn't be right, and B, it already exists out there in excellent form. I'll just give a brief synopsis of some of the things that she suggests because I entirely agree. And again, there's no need to be repetitive. And she does an excellent job.

So she certainly mentions collagen and bone broth. She also mentions various sources of omega fatty acids that are often lacking in people's diets that they should pay extra careful attention to get. So things like walnuts, flax, fatty fish. I personally am a big believer in supplementing with liquid form fish oil.

That's what I do. Why am I a big believer in that? Well, I don't tend to cook much fatty fish. I love the taste of it if it's prepared right, but I don't tend to do that very often. So I use a liquid form fish oil or capsules, but the liquid form is generally more affordable.

This was discussed in an episode that I did with Dr. Rhonda Patrick. So we can put a link to that particular segment in the show note captions. It's also suggested that we eat a lot of leafy greens, so dark leafy greens. You're probably noticing a lot of these recommendations are kind of typical for what people describe any time they're talking about nutrition for health.

She highly recommends people get enough folic acid for the role that folic acid plays in DNA synthesis and repair of skin cells as among other cells and cell proliferation. And of course we should get our colored fruits and veggies. So our oranges, our strawberries, the reds and oranges are critical out there.

And she also highlights something very important that I want to reiterate, which is that we have a critical need for vitamin A for our skin health. And this was covered, albeit through the lens of exploring the pharmacology of tretinoin and those retin-A compounds. But vitamin A is crucial for a number of different processes within the cell types that make up skin.

She appropriately cautions against supplementing with vitamin A because as a fat soluble vitamin, it's very easy to overdose vitamin A. If one is supplementing with too much of it, she recommends rather getting enough vitamin A from things like oranges, carrots, sweet potatoes. She recommends as much berry intake as is appropriate for someone and one can afford.

The berries are so delicious, but they tend to be expensive depending on time of year. Ingesting things like garlic because garlic has sulfur, which is key for collagen synthesis and repair. And she talks about the critical role of taurine. Anyway, she does such a terrific job of describing the nutrition for skin health and skin appearance.

Those are just a few of the highlights. I do encourage you to check out that video and her other content is spectacular as well. Again, she has an Instagram account, YouTube channel that are really wonderful. So again, without doing a deep dive into nutrition, decide whether or not you're going to be vegan, vegetarian, omnivore or carnivore, and then make sure that you're getting enough of the vitamins and minerals and micronutrients from your foods or supplement if necessary.

But note that caution about vitamin A supplementation in excess. And also make sure you're avoiding excessive amounts of highly processed foods. You know, I mentioned earlier these advanced glycation end products. These are things that are present in a lot of processed foods, like crackers and chips and things like that, that make those foods inflammatory.

So you're getting the theme now. Inflammation is bad, not just for the skin, but for all organ systems of the body. It's not just about the high density of calories and the high density of taste present in highly processed foods. Those are problematic, but a lot of the issue with these highly processed foods is the high heat conditions used to make those foods stable on shelves or stable in packaging over time.

Okay, so there's a whole discussion to be had here that frankly, I don't think Amy had enough, but that is outside the scope of today's episode. The point is that when these highly processed foods are basically made, right, they're constructed, they involve the interactions between sugars and proteins and fats at high heat that make them stable on the shelf or in packaging.

And those can be very inflammatory. And that can show up in the form of reactive skin. It can make your psoriasis worse. Yes, it can make your acne worse. It can make your skin more tender and painful. It can make your skin basically more reactive to some of the underlying predispositions you might have, either because of genetics or other things you're doing or not doing.

Maybe you're going through a particularly stressful time. Maybe you're getting a little bit of extra sun and you're eating more highly processed foods and those things are combining and making your skin break out or flush more than it would ordinarily. Again, there's so many reasons to eat most of your foods from non-processed or minimally processed sources.

And of course, and now I sound like a broken record 'cause you can hear this all over the internet, ingesting foods that are excessively high in sugar, excessively high in sugars combined with fats, just not good to do. Pro-inflammatory, it's going to cause all sorts of issues. And we're going to get into this more as it relates to acne in particular, because as you probably know, when you ingest foods that are high in sugars or even just carbohydrates generally, that also contain a lot of fats, and in particular when those foods are highly processed, well, then you initiate an inflammatory response and you often can initiate additional things happening in the pores of cells that can start to really aggravate acne and cause more acne.

This has to do with the whole insulin pathway. So when we talk about acne, I'll talk about diets that create a high glycemic load. We're not necessarily talking about the glycemic index of food. You may know that when people measure the glycemic index of food, they're looking at the blood sugar response after eating that food typically in isolation and not in combination with other foods.

What I'm talking about is eating combinations of foods that induce high levels of insulin, high levels of blood glucose, that then leads all sorts of things in the hormone pathways and cell growth pathways that exacerbate acne. So we'll get there in a moment, but I think the take-home message around nutrition is pretty clear.

So much so that I don't want to spend any more time on it. We all know what the best nutrition really is for us, regardless of whether or not you're vegan, vegetarian, omnivore or carnivore. It's non-processed or minimally processed foods representing probably anywhere from, let's say 75 to 100% of your food intake, depending on how strict you want to be.

And then sure, make some room if you want for some processed foods, but just know that those advanced glycation end products and the high glycemic load that comes from those processed foods can really exacerbate inflammatory responses in skin and set forward a whole domino set of issues related to hormone pathways and cell growth pathways that make everything, acne, psoriasis, and overall appearance worse.

Yes, your skin will appear to age faster. And on the positive side, most of the foods that we think of as healthy and anti-inflammatory are actually quite delicious. So enjoy. Ah, and I forgot to say what's absolutely clear. You know that myth that they told us when we were teenagers, that eating a lot of fried food would make you break out, would make your skin worse?

Guess what? It's true. That high heat preparation required for creating things as delicious as the donut or French fries, right? There's a reason people love these foods. They're so delicious. They do cause problems. They're pro-inflammatory. Does that mean you can never have a French fry? No. You decide what's best for you, but know what you're doing.

As a segue to talking about acne, we need to talk about the gut microbiome. And this is a direct outgrowth of our discussion about nutrition. Here's the simple takeaway that I believe everyone should follow, not just for sake of healthy appearing skin, but also for sake of every organ and tissue system in your body, which is the data clearly show that ingestion of sufficient amounts of fiber, so prebiotic and probiotic fiber, so fruits, vegetables, sometimes this can also come from grains.

Some people will supplement with additional fiber if they feel they need it, as well as ingestion of low sugar fermented foods. I've talked about this before. So regular listeners of this podcast may have heard this. Things like kimchi, sauerkraut, the sort of sauerkraut that has to stay in the fridge.

So not the stuff that's stable on the shelf at room temperature. Anything containing a brine, that salty brine. So pickles, but not the pickles that are stable at room temperature, the ones that have to be kept in the refrigerated section of the grocery store. These low sugar fermented foods are powerful enhancers of the gut microbiome.

And when the gut microbiome is healthy, you have reduced overall inflammation in the body. This is often reflected at the level of the skin. And basically skin health and the youthfulness appearance of skin is enhanced, okay? This can also help with conditions like acne or psoriasis, especially in conditions where there's a direct immune system skin relationship that we'll talk about more in a little bit, okay?

So I highly recommend people have anywhere from one to four servings of low sugar fermented foods per day, or try and enhance the health of their gut microbiome generally. Maybe you take a pill probiotic, although those can be very expensive. There's a little bit of data suggesting that if you chronically take pill probiotics that yield very high levels of bacteria, well then maybe there's some associated brain fog.

That's a little unclear, pun intended, but they are very expensive. They have to be kept refrigerated and let's face it, low sugar fermented foods, if you find the ones that you like, are really great to ingest 'cause they're tasty and they're good for you. Now, why am I talking about this?

In part, because we keep coming back to inflammation as a general issue for skin health. And that points us also towards some specific do's and don'ts as it relates to lifestyle. Let's face it, pun intended, if you sleep well, so maybe you need six hours, maybe you need seven, maybe you need eight, maybe you need nine, but if you sleep well on a consistent basis, your skin is going to look so much better, so much healthier, more vibrant than if you are not getting enough sleep.

If you drink alcohol and you wake up the next morning, you know your skin's going to look puffy, it's not going to look good. But many of you can ingest alcohol without issues. I've done an entire episode about alcohol. Yes, it's a poison, up to two drinks per week.

For adults who are non-alcoholics, it's probably safe. Zero is better than any, but let's face it, alcohol is going to exacerbate most skin issues. This is just clear from the literature. Doesn't mean you never have a glass of wine, doesn't mean you never have a beer or a cocktail if that's your thing, but alcohol consumed in excess, and it doesn't take much to get there, is going to cause sleep issues, microbiome issues, so indirectly and negatively impact the skin appearance and health, and indirectly and negatively impact the health of other tissues in your body.

But it's clear, some of that is reduced to increase inflammation, some is related to decreased sleep quality or duration. So get great sleep, avoid alcohol in excess, maybe avoid it altogether, drink plenty of water. This sounds like such basic advice, but proper hydration is key. Get enough water and electrolytes.

It absolutely will impact your inflammation levels by reducing them, it absolutely will impact your skin health and appearance in a positive way. So these are just basic things that I'd be remiss if I didn't mention. The other one is smoking and nicotine from non-smoked sources. So it's very clear that smoking, vaping, dipping or snuffing is bad for skin appearance and health.

Bad, bad, bad, every dermatologist said this, why? Well, with smoking, you can imagine why, okay? A lot of carcinogens and toxic end products generated from smoking, even from vaping. Yes, even from vaping, it will make your skin age faster, that's clear, but it's also the substance itself. Why? All of those things, in addition to increasing inflammation, nicotine itself is a vasoconstrictor, so you're doing the exact opposite of what you want when it comes to skin health and appearance.

And that's why people take things like BPC-157, that's why people take nicotinamide, that's why people are trying to improve the hydration status of their skin. So if you're somebody that's vaping nicotine or even taking nicotine in some other form, pouch or smoking nicotine, and you're interested in having youthful appearing skin, you are really shooting yourself in the, I don't know, face.

And as we all know, our emotions impact the appearance of our skin, and yes, it can exacerbate so-called breakouts. And we'll get to that in a moment as to what the exact pathway is. But I've done entire episodes about controlling your stress. We have a master stress episode that talks about real-time tools that you can use, like the physiological psi.

Provide a link to a clip about the physiological psi, it's the fastest way that I'm aware of to reduce one's levels of stress. This is something my laboratory has studied in detail at Stanford. There are also things you can do, and we're all aware of what they are, proper sleep, meditation, non-sleep deep rest.

We'll provide a link for that. All things that we can do that are zero cost, very minimal time investment. Physiological psi takes about 10 to 15 seconds. Non-sleep deep rest, aka yoga nidra, sometimes called, takes anywhere from 10 to 20 minutes per day. And that reduced stress can dramatically improve not just the health, but the appearance of your skin.

And it makes perfect sense as to why that is. The stress hormones such as cortisol, but other hormones too, such as adrenaline, when they are chronically elevated, because of the fact that adrenaline impacts vasoconstriction in the skin, it's gonna reduce blood flow to the periphery, to the skin. It can cause all sorts of issues at the level of nerve endings that can lead to, believe it or not, enhanced flushing when we're under stress.

This is why we measure the galvanic skin response. So not just sweating, but also blood flow and other things to the skin when we are studying stress. Okay, so direct relationship between stress and skin appearance. Learn to control your stress. Stress is part of life, but learn to control your stress in real time and through tools like non-sleep deep rest that are zero cost that can help you reduce your overall levels of stress, get great sleep.

Don't use nicotine. If you do use nicotine, know what you're doing. Maybe use it sparingly and please don't smoke or vape it, dip it or snuff it. There are other forms and I don't recommend those forms because they're very addictive. And keep in mind that things that improve blood flow, reduce inflammation, give you lower stress, better sleep, all of that is going to make you look more youthful.

It's not an imagined effect, it is real. Let's talk about acne. Acne is very common. It impacts anywhere from 80 to 90% of young people at some point. Some people get very bad cystic acne, you know, deep acne in the cheeks, on the back of the neck, the back, it can be very uncomfortable, very painful.

Some people only get the occasional pimple, but they get them very deeply, they're very painful. And look, nobody likes acne. Nobody likes the appearance of acne on themselves. It can be very distressing for people, can cause additional stress that then feeds back in terms of inflammation. And, you know, I guess my first, you know, request, I suppose, I can't tell people what to do and never do, but, you know, for people that have acne, you know, be compassionate, okay?

Young people, be compassionate. I remember when I was younger, some of the kids with bad acne got teased and it really upset me. It was really frustrating, especially when going through puberty because there's this hormonal component to acne. Now, fortunately, there are things that we can do for acne.

I'll provide a link to one of the major sources I used for researching this episode. I also, of course, spoke to dermatologists, one of whom really knows an exceptional amount about acne and its relationship to the immune system. The paper that I'm referring to now is a systematic review and network meta-analysis of topical, pharmacological, oral pharmacological, physical, and combined treatments for acne vulgaris, which is the technical name for acne.

There are a lot of things that impact acne. Let's just briefly talk about what acne is. Anytime you talk about acne, you're usually thinking about pus or oil. That's called sebum. The sebum accumulates in, essentially, the follicle around the hair. This also occurs on non-hairy skin or where there's just tiny little hairs that often aren't visible.

That's why it's very unusual to get acne on, say, the glabrous skin of the palms. I suppose it could happen, but it's very rare. At any given moment, 10% of people worldwide will have acne. As I mentioned, up to 90% of young people have acne, so very common, very distressing.

The accumulation of that sebum in the follicle can be due to a number of different things. Some of it can be related to androgens, things like testosterone, increasing the amount of sebum that's produced, okay? This is why you often see acne during puberty. In addition, the anabolic, the pro-growth effects of androgens, such as testosterone, and by the way, these occur in both males and females because both males and females have testosterone and estrogen.

The androgenic effects of testosterone can also cause hypertrophy growth of the hair follicle, right, so an increase in the number of keratinocytes, the cells in and around the follicle, which can compress that and hold some of that additional sebum beneath the surface, and that's why you're getting a swelling of what looks like a pimple or a cyst.

So there's the potential for a hormonal influence on increasing acne. Now, if someone's going through puberty, you just have to deal with that increase. If there's a sudden increase in acne when one is post-puberty, you may want to look at levels of androgens that are being produced. And nowadays, with increasing numbers, apparently, of things like polycystic ovarian syndrome, which in part relates to increases in androgens, this is becoming an additional concern.

So getting a quality blood test, looking at androgen levels over time can be very beneficial for both males and females. Now, in addition, insulin that is related to our diet. So insulin and glucose generally go up together or down together, depending on whether or not we're ingesting foods or amounts of foods that greatly increase our insulin and blood glucose.

So insulin is part of an anabolic pathway as well, a cell growth pathway, pro-growth pathway, we should call it, that involves mTOR, mammalian target of rapamycin, that is a general growth signal for cells. So this occurs in the eye, this occurs in the liver, mTOR is involved in growth of cells of all kinds, including cells within the skin.

When our diet increases the amount of insulin and glucose to a degree that is in excess of some threshold, that's going to be different for everybody, depending on your activity levels, your metabolism, the way you manage insulin. When that happens, you get increases in mTOR that then can feed back on those androgen receptors, increase the levels of things like testosterone further, that then feed back on the production of increased sebum, okay, that oily stuff, increased keratinocyte proliferation, and you get more acne.

In other words, having a diet that has a high glycemic load or evokes a large insulin response can be problematic. So what to do? Well, we talked about it before, you wanna eat mostly non-processed, minimally processed foods, you definitely wanna exert portion control, right? You don't wanna eat much sugar or sugar in excess, you don't want big spikes in insulin and blood glucose, you want to avoid an inflammatory diet.

So again, fewer, if any, highly processed foods because of those glycation end products that we talked about before. And on the positive side, if one exercises something like say intermittent fasting, and here I don't necessarily think young people, especially people going through puberty should do this because they're growing, they need nutrients, so you have to strike that balance between getting enough nutrients and not overloading the system with insulin, glucose, and calories.

But things like intermittent fasting could be useful, or making sure that if you ingest complex carbohydrates, as I mentioned, I do, okay, I'm an omnivore, that you don't do it in excess to the point where you're getting big spikes in insulin and blood glucose. All of this, the dermatologists tell me, can help serve to reduce acne.

And while it might seem indirect, you know, this relationship between testosterone and sebum accumulation, the relationship between insulin and mTOR and increased testosterone and sebum accumulation and growth of the keratinocytes, these are real pathways that have been established. And some of those are discussed in detail in the review.

So much so that there has been the exploration of specific foods, in particular dairy and whey. You know, we hear a lot about ingestion of whey protein. It's a very high quality protein, high bioavailability, high in the amino acid leucine, which for those of you that are interested in muscle building and repair, there's a lot of discussion about leucine being a critical component there.

You want leucine. But it does appear that people that over-consume whey, people that over-consume dairy can run into issues. Now, does that mean you shouldn't consume whey protein? No, I take whey protein. Do I suffer from acne? No. If I did, would I reduce my whey protein intake? Well, I might decide to run a bit of an experiment where I reduce the amount of whey protein that I eat for a little bit and see how that goes.

Should I reduce the amount of dairy I ingest? Ah, well, here's where things get interesting. So in discussing this with a dermatologist who also happens to know a lot about nutrition, they told me something very interesting. A lot of people think that high-fat dairy will exacerbate their acne, but here's the situation.

Non-fat and low-fat dairy has emulsifiers, this is actually based on work I believe, some of which was done at Stanford, that can spike insulin more than full-fat dairy. So some people, in an attempt to reduce the amount of acne they're getting, will move from high-fat dairy, or full-fat I should say, to non-fat milk, or non-fat dairy, or low-fat dairy, and their acne will actually get worse, and that could be because of the insulin spike associated with some of the emulsifiers in that non-fat and low-fat dairy.

So what this means is that you don't have to avoid dairy altogether, but you might be better off ingesting full-fat dairy. You might be best off not ingesting any dairy at all, maybe you want to run that experiment on yourself and just see what works and what doesn't work, or if there's no change at all.

In addition, if you're consuming a lot of fried foods, so those French fries, you're ingesting cheeseburgers and things of that sort, it may not be so much the fat content of those meals, but rather the big insulin response that occurs when we ingest high-fat meals in combination with things like sugary milkshakes, or fried foods, like French fries and things of that sort, that's leading to the acne by way of increased inflammation.

All right, so there are a lot of different pathways, inflammation, androgens like testosterone, insulin leading to increases in testosterone and inflammation, a lot of pathways converge to exacerbate acne, and oftentimes it's just the removal or even just the reduction of some of this food intake or types of food intake that can really lead to big improvements in one's acne.

So all of these things combined to support lower inflammation, appropriate amounts of sebum production, because you do need sebum production, you do need keratinocytes in and around the hair follicle, but you don't want too many of them, and so on. But what can be done to directly address acne?

Well, there are a number of different prescription treatments that your dermatologist can suggest, but one thing that all the dermatologists agree upon is, first of all, getting adequate sleep, reducing stress, taking care of your gut microbiome, the nutrition recommendations that we've been talking about up until now, but also, get this, this is interesting, not over-cleansing.

A lot of people with acne will start to wash their face constantly and will often use harsh cleansers that can exacerbate that acne, either by virtue of removing some important skin microbiome components that then lead to even other infections like fungal infections or additional inflammation, 'cause you're removing that microbiome barrier, but they all recommend regular cleansing of the skin, usually two or three times per day, but not in excess of that, using a gentle, unscented, unfragranced cleanser, okay?

So there are a number of different types of these. I personally, basically my entire life that I, at least as far as I can remember, I've always used unscented, unfragranced dove soap, okay? I have no relationship to dove soap. I'm sure people out there are going to say, "Oh my goodness, you know, it contains a bunch of things that are bad for you," but that's what's worked for me and not the liquid form, just bar soap, and there are things like Cetaphil, these are some brand names, and there are a bunch of other more sophisticated, gentle cleansers that one could use.

There are also a lot of products out there that contain what's called salicylic acid, okay? This is often as, you know, a clear fluid that you put onto a cotton ball or a tissue and then you spread on the face. It's very important, very, very important that if you're going to use these products that you do it on clean skin, that is skin that's been cleaned with a combination of mild, zero-fragrance soap and lukewarm water, okay?

Because of the relationship between inflammation and acne, that's what gives it its red appearance. You don't want to use extreme temperatures of especially hot water when washing your skin. So lukewarm water, mild soap, and then, and only if it's been recommended by your dermatologist, the salicylic acid. Salicylic acid comes from the same class of drugs as aspirin, so it tends to reduce keratinocyte stickiness, right, the extent to which those cells stick together.

Why do I mention aspirin? Well, you may have heard that some people will take aspirin to reduce the stickiness between their platelets in an attempt to improve heart health. We'll cover that on another episode at some point. But salicylic acid reduces the stickiness of the keratinocytes, so it can lead to less clogging of the pores by accumulation of keratinocytes, or I should say by less accumulation of the keratinocytes, and it can reduce swelling in and around the area related to the acne.

Sometimes if people get an acne pimple, especially if they have an event or they don't want to be seen with that pimple, the use of a little bit of corticosterone cream put on there can reduce the redness or swelling. The dermatologists tell me you should absolutely not pop your pimples.

Part of the problem when you pop a pimple, I know there are entire videos about this online. I know, please don't go look at them. The whole community is around this, it's super gross. But I know people find it very satisfying in some cases to pop these pimples, get the infection out.

While there are certain use cases for that where someone has an infection, it just absolutely needs to get out, then be cleaned, then covered with a bandage and maybe some topical antibiotic, that would be a use case for that. The dermatologist practically begged me to tell you don't pop your pimples because A, they will go away in not too much time if you leave them alone, and B, you can always put a little bit of corticosterone cream on top of them to reduce the redness or swelling.

But most importantly, they tell me that when you pop those pimples, what ends up happening is you get a mechanical, a physical disruption of that area, which to you might just seem like, okay, whatever, it turns a little bit red and that's transient, but you get the influx of what are called matrix metalloproteases.

These are enzymes, and remember, anytime you hear an ace, it's usually an enzyme, matrix metalloproteases that then, and go eat at the extracellular matrix, and then you can get an indentation scar that is permanent, okay? So if you're concerned about the appearance of your skin, avoid popping those pimples.

I know it can be hard to do, but really try and avoid popping pimples. It can lead to scarring because of the matrix metalloproteases and the eating away of the extracellular matrix. Keep the area clean, cover it up if you need to, get some corticosterone cream on there if you want to reduce the redness.

If it's really bad and you have some big important event, like you're getting married tomorrow and it's right on the tip of your nose or something like that, then you can potentially go to the dermatologist and get it injected with a corticosteroid to reduce the redness in a more potent way.

But they did ask that I ask you to please not pop your pimples. And if you're somebody that suffers from acne, I'd like you to know I provide a link to a paper in the show note captions entitled "Acne and Diet, A Review of Pathogenic Mechanisms." And I also provide a link to the review I mentioned before that covers all of the other aspects of treating acne, topical, pharmacological, oral, pharmacological, physical, and combined treatments for acne vulgaris.

Because again, I do sympathize with the fact that acne can be very distressing, very painful. Fortunately, there are a number of different avenues that you, without a dermatologist, but ideally you and a dermatologist can use to attack acne at the level of inflammation, through diet, through lifestyle, if needed prescription medications.

And again, gentle cleansing and thinking about the various things that indirectly will impact that acne. So much so that a few of the derms told me that they have patients young and old who will be suffering from really bad acne that will sometimes just make a few adjustments to their diet, the exclusion of certain things, mainly highly processed foods, maybe reducing dairy a little bit or weigh a little bit or completely and increasing the amount of things that reduce inflammation.

So more fruits and vegetables and meat, fish, eggs from healthy sources and seeing dramatic improvements in acne. So that's always reassuring to hear. It doesn't always require a prescription medication, but if you need it, you should take it. Okay, let's talk about rosacea. Rosacea is reddening of the skin.

And some people suffer from this pretty severely, other people mildly, some people transiently, but it tends to be kind of distressing for people. And the reason it's distressing is that it can look like blushing or flushing of the face when in fact one isn't emotionally embarrassed. However, being embarrassed or having any flushing of the skin can exacerbate existing rosacea.

So it's thought to be caused by a combination of genetics. There can perhaps be some, again, over-inflammation of the skin, which probably reflects inflammation more globally at the level of the gut and body, et cetera. We've been talking a lot about that today. And there are things that can exacerbate rosacea such as alcohol intake or anything that acts as a vasodilator that dilates the vasculature innervating the skin.

So the approach to treating rosacea is pretty much similar to the other things that we've talked about, consuming a low inflammation, low glycemic load diet, trying to get enough sleep, keeping alcohol intake in particular to a minimum or cutting out alcohol completely. The reason I say in particular is that a lot of people that suffer from rosacea who cut out alcohol completely essentially eliminate their rosacea or dramatically reduce it.

So oftentimes it's alcohol that's the culprit either directly or indirectly, we don't know. Again, alcohol is a poison, but it could be the indirect manner in which alcohol impacts sleep and the gut microbiome negatively that's causing the rosacea. Without knowing the direct or indirect mechanism, reduce or even eliminate your alcohol for a bit and see if your rosacea improves.

That will give you a strong indication of what might be going on and even better, it could give you a potential solution to the problem. Now, for those that don't experience a reduction or elimination of rosacea, if you eliminate alcohol, get your sleep right, get your diet right, there are some additional things you can do.

First of all, you want to follow the same recommendation we talked about for acne, which is also the general recommendation for skincare. Use lukewarm water, not excessively hot or cold water, a gentle unfragrance cleanser. You want to use sunscreen regularly. Remember, sun damage to the skin is also inflammation, so that's going to exacerbate rosacea.

And of course, sunlight, because of the release of nitric oxide, is also going to act as a vasodilator. Does that mean you have to go full beekeeper mode? No, it doesn't. You can if you want to, I suppose, but use a quality mineral-based sunscreen, which we talked about earlier in the episode.

And you should use some sort of moisturizer to help lock in the moisture within your skin. You could use things like hyaluronic acid or use any kind of gentle moisturizing cream that's not going to cause inflammation or kind of irritate the skin in any way and can keep the moisture within the skin.

And there are a lot of different versions of these available out there. And frankly, a lot of them are not terribly expensive. You can find super expensive varieties of any and all these things. But many of the things that meet the criteria of gentle unfragrance cleanser, SPF 30 mineral-only sunscreen, as well as a quality moisturizer are not necessarily the most expensive available.

And what justifies the higher expense in some cases could be, I don't know, the silkiness or the packaging. It could be any number of different things. I'm not going to say that the cheapest varieties are necessarily as good as the most expensive varieties, but I do think, and the dermatologist that I spoke to definitely confirmed that there's a lot of price inflation out there related to kind of the overall milieu of packaging and purported exclusivity of certain skincare products.

Look for the things that meet the criteria. You are trying to establish for your skincare. But just like with acne, just like with general skincare, if you have rosacea, you want to think about mild treatments for the skin at the level of cleaning, at the level of sun protection, at the level of locking in moisture.

And then there's some additional things that if you can spare the expense could also be beneficial like nicotinamide, niacinamide, as it's also called. Or there's also been some evidence that things like licorice root can be a benefit, okay? These things are typically found as a topical ointment or in a topical ointment.

But in the case of niacinamide, nicotinamide, we talked about how this can be available in an ointment form, a topical form, or it can be taken as two 500 milligram dosages per day. I gave you the long list of the various mechanisms by which it can improve skin health, reduced inflammation, production of collagen, et cetera.

All of that still holds for the potential treatment of rosacea. Be sure to avoid any kind of things that are acting as strong astringents or that increase heat. So people who have rosacea will often try to avoid hot peppers. So spicy foods of any kind, I know that's tough.

I'm somebody who really enjoys spicy foods. So if you have to avoid spicy foods, I sympathize with you. That's rough. Anything that acts as an astringent or can really irritate the skin from the inside or from the outside. So think not excessively hot foods as it relates to spicy or temperature.

Things of that sort. Now, I should point out there are different types of rosacea. The dermatologist I spoke to who is expert in rosacea told me there are four major types of rosacea. Many of them respond to the sorts of guidelines that we've been talking about up until now.

Some of them that also include acne need some additional treatment. Talked about acne treatments that can be easily folded into the treatment for rosacea. There are people who have very stubborn rosaceas. This may be due to excessive use of cleansers. And again, we're talking about how over cleansing can really be a problem.

So we're not saying don't wash your face. We're not saying don't take a shower, please do. In fact, and I should have said this earlier, by the way, for a lot of reasons related to your comfort and appearance and other people's comfort. After you work out at a gym, regardless of whether or not you're rolling around on the floor with a foam roller, or you're rolling jujitsu, or you're lifting weights, you're doing cardio, it is a good idea to take a shower and cleanse with a gentle cleanser as soon as possible.

I know this sounds like just basic advice, but a lot of people just throw on a clean shirt or they don't rinse off or they don't wash their face and they're wondering why they're getting all sorts of skin issues. Well, there's a lot of bacteria in gyms, a lot of sweating people.

There are a lot of bacteria on you, a lot of bacteria on the equipment. And yeah, you can spray down the equipment and do these various things, but it's a good idea to shower as soon as possible, or to bathe rather as soon as possible, wash your face after going to a gym for your sake and for the sake of others.

Now, some rosacea is very stubborn, meaning it does not go away even if somebody makes all the appropriate lifestyle adjustments, tries any number of different medical treatments. And by the way, rosacea is a medical condition. And in some cases, people will get angiomas, you know, the accumulation of blood vessels near the surface of the skin that can be, you know, for them something they don't want.

So we could say unsightly, but they just don't want it. Or in some cases they'll treat their rosacea and then they'll get an accumulation of broken vessels near the surface of the skin. This is pretty common for people that experience rosacea and treat rosacea. For these people, there is a treatment, it has to be done in a dermatologist's office called pulse dye laser, where they use a laser of a particular wavelength that can penetrate, excuse me, the superficial layers of the skin.

And now you know how different wavelengths of light can penetrate to different depths within skin and destroy the blood vessels or the broken blood vessels that then call in immune system cells to clear out the destroyed endothelial cells and other stuff around it and take it away, get rid of those blood vessels that sit beneath the surface.

Let's talk about psoriasis. So when I was researching this episode, I asked the dermatologist, is psoriasis related to yeast or overproduction of skin cells? And what they told me was really interesting. They said for more than 80 years within the dermatologic community, it was thought that psoriasis was just an overproduction of skin cells, but it wasn't really known what the source was.

And it turns out that now almost all the derms, at least the ones I spoke to, said that it has something to do either directly or at least powerfully and indirectly with the immune system. So what can be done to treat psoriasis? You can probably guess. Things that reduce the overall level of activation in the immune system.

Not so much that you become susceptible to infections 'cause that's not good, but you treat this like any other autoimmune condition. There are now drugs, these are prescription drugs, that directly target the interleukins, the components of the immune system, that are directly involved in psoriasis, such as interleukin-17 and interleukin-23.

And I'm told that these drugs are very effective in the treatment of psoriasis. So that's very reassuring. You know, I know, especially in communities online that are focused more on behavioral tools and nutrition-based tools or supplementation-based tools, of which I am, right, we focus on those. But as you probably noticed in this and other episodes of the "Huberman Lab" podcast, we also talk about prescription drugs that have proven to be very effective in certain conditions.

So it's very reassuring to hear that there are excellent prescription drugs that can target the specific interleukins that are overactivated in psoriasis because psoriasis is now known as an overactivation of the immune system and a kind of turning of the body on itself, if you will, to create this itchy, scaly, uncomfortable, and in some cases, unsightly overproduction of skin cells at the scalp and elsewhere.

Okay, so we've covered a lot of topics thus far. We've talked about skin biology. We talked about various skin conditions that are very common, such as acne, psoriasis, and so forth. We talked about ways to increase the youthfulness or the appearance of youthfulness in skin that are based on data, some that are a bit more experimental.

And we talked about even some laser procedures and phototherapy, things of that sort. And at the same time, I acknowledge that there are many topics and conditions related to skin health and skincare that we did not talk about. We didn't talk about eczema. We didn't talk about Botox. We didn't talk about an enormous number of topics that I know are of interest and relevant to many of you.

So as a consequence, the plan is to host various expert guests, both dermatologists, expert in particular areas, as well as, yes, a cosmetic surgeon who, believe it or not, does not like to cut, but rather likes to use fairly non-invasive procedures that touch on some of these very same mechanisms.

Yes, injections of certain things, things that operate at the surface level of the skin, and sometimes surgical procedures that, you know, I know when people hear cosmetic surgery, they think, oh, people just trying to improve the youthfulness of their look or something of that sort. But, you know, that also relates to certain serious skin conditions for which surgery and non-surgical approaches can assist in.

So the point is that any discussion about skin health and skincare is going to be an ongoing discussion, one that I do plan to continue on this podcast in the form of expert guest episodes, maybe even another solo episode. We've occasionally done so-called toolkit episodes where we summarize some of the main points of previous solo episodes and that arrive with guest episodes and that reflect the latest knowledge that gets published in between episodes.

I do plan to cover this topic in more detail going forward. Meanwhile, I like to think that what I've covered today provides at least an introduction to the biology of skin and an understanding about the various things that we all can and should do for our skin health and appearance, as well as ways to attack certain pain points related to certain skin conditions that come from expert sources, from excellent literature that has been established over many, many decades.

And I personally find this organ that we call skin to be infinitely fascinating, not just by virtue of what it does, but by virtue of all the different organ and tissue systems that it interacts within our body, and by virtue of the fact that our skin is this incredible living organ on the outside of our body that tells us oh so very much about how we and others are doing in terms of our immediate and potentially our long-term health.

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