Huberman Lab - The Science of Healthy Hair, Hair Loss and How to Regrow Hair

Episode Date: April 10, 2023

In this episode, I explain the biology of hair, hair growth, why hair growth slows and what causes hair to stop growing and/or “fall out.” I discuss the essential role of hair stem cells and other supporting biological factors for healthy hair growth. Then I describe various approaches (mechanical and chemical) to slow hair loss by increasing blood flow to hair stem cells, including minoxidil, tadalafil, PRP, microneedling, Botox and ketoconazole treatments. I also discuss how age-related hormone changes cause hair loss and explain the effectiveness of treatments such as caffeine, saw palmetto, growth hormone, finasteride and dutasteride. For all hair growth options, I describe potential side effects, how soon to expect results and the amount of hair regrowth to expect and I highlight effective combination treatments for hair regrowth even in hair “dead” (bald) zones. For many listeners, thinning, brittle hair, or pattern baldness are a source of anxiety and stress. This episode explains the mechanisms underlying hair regrowth tools and the science behind them so that you can evaluate potential treatments and associated side-effect profiles and select the best one(s) for you. For the full show notes, visit hubermanlab.com. Thank you to our sponsors AG1 (Athletic Greens): https://athleticgreens.com/huberman Helix Sleep: https://eightsleep.com/huberman HVMN: https://hvmn.com/huberman ROKA: https://roka.com/huberman LMNT: https://drinklmnt.com/huberman Supplements from Momentous https://www.livemomentous.com/huberman Timestamps (00:00:00) Hair (00:04:13) Sponsors: Helix Sleep, HVMN, ROKA (00:08:04) Psychological States & Hair (00:13:19) Hair Anatomy & Stem Cells (00:26:05) 3 Phases of Hair Growth (00:35:40) Sponsor: AG1 (Athletic Greens) (00:36:55) Minoxidil & Blood Flow (00:45:37) Increase Blood Flow: Massage, Tadalafil, Platelet-Rich Plasma (PRP), Microneedling (00:56:10) Microneedling, Minoxidil & “Dead Zones” (01:00:13) Sponsor: LMNT (01:01:25) Botox Treatments (01:06:27) Androgens, Hair Growth & Pattern Hair Loss; Scalp vs. Beard Hair (01:15:46) Topical Caffeine & Slowing Hair Loss (01:21:06) IGF-1: Growth Hormone & Sermorelin; Insulin Sensitivity: Myo-Inositol (01:25:52) Iron & Hair Growth (01:27:04) 5-Alpha Reductase & Saw Palmetto; Curcumin (01:33:22) Ketoconazole & Offsetting Hair Loss (01:38:46) Topical & Oral Finasteride (01:51:00) Post- Finasteride Syndrome (01:56:01) Dutasteride (01:58:53) Mechanical & Chemical Stimulation for Hair Growth (02:02:46) Zero-Cost Support, YouTube Feedback, Spotify & Apple Reviews, Sponsors, Momentous, Social Media, Neural Network Newsletter Title Card Photo Credit: Mike Blabac Disclaimer

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 hair. Hair is a topic that occupies the minds of many people. There are people that are losing their hair and want to halt or There are people that are losing their hair and want to halt or reverse that loss of hair. And today we will talk about all the ways that science has taught us. We can slow or even reverse hair loss. I confess that researching today's topic was a particular joy for me, not because I'm

obsessed with hair, mine or the hair of others, but because hair turns out to be fascinating from the perspective of seller biology and stem cells, which is a topic that I've long been interested in and that for much of my career, I've focused on in the context of development. So when your brain and your nervous system develop, it develops from a small batch of cells that turns into many, many trillions of cells. And it does that by cell replication, Something that we call the cell cycle, and we'll talk a little bit about this, and so called mitosis today. I promise not to get

into too much detail, but what makes hair so very interesting from a biological standpoint is that every hair, every single individual strand of hair has its own little stem cell niche, meaning its own little pocket down there in the follicle, in which specific stem cells give rise to those hairs for different durations of time, depending on the hair, where it is on your body, etc. So for instance, the hairs on your head will undergo ongoing growth for four to six or even eight years. So were you to not cut your hair? It would continue to grow. One? It would continue to grow. One single hair would continue to grow. I guess we could say all the hairs will continue to grow for up to eight years.

That is very different from, for instance, your eyebrows, which have a much shorter period of hair growth lasting on the order of months. That's why you don't see people with eyebrows that extend down to their waist, but you can see people with hair on their head that extends down to their waist if they don't cut it. Now that discrepancy illustrates for us just how incredible hair follicles and the stem cells that reside within hairs are and their enormous potential to give rise to these things that we call hairs, which are simply proteins, of varying length. So today we are going to address what determines the length of a hair, or rather what determines how long a hair continues to grow before it ceases growing and eventually falls out. We're going to

talk about what regulates those stem cells, what allows them to continue to produce hair or cease producing hair. And as we do that, you will learn all the biology in clear simple terms, regardless of your background, that will really set the stage for understanding what we'll also talk about, which is how to slow hair loss or halt hair loss entirely or even reverse hair loss. So we will talk about hormone related hair loss in both men and women.

We will talk about some of the mechanical and stress related influences on hair loss. So we will talk about hormone related hair loss and both men and women. We will talk about some of the mechanical and stress-related influences on hair loss. And we will talk about the chemical and mechanical approaches to halting and reversing hair loss. Everything from to thyroid estrogen, IGF-1 pathways. Again, all made very clear, regardless of whether or not you have a background in biology or not. I will also dispel some of the common myths about balding and hair replacement. If you've heard, for instance, that you inherit your patterns of balding from your mother's father, that is not true. Although it is true that you do inherit certain genes that influence whether or not you have a

predisposition to balding in particular parts of your head and believe it or not even in particular parts of your body But it is not the case that you can simply find a photo of your mother's father say at age 50 or age 60 or 75 and determine whether or not you'll have the exact same pattern of hair loss So that's a myth that I'd like to dispel right here and now and I will dispel some of the other myths about hair loss, hair replacement, and hair regrowth as well. 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 Helix Sleep. Helix Sleep makes mattresses and pillows that are of the absolute highest quality. I've talked many times before on this podcast about the fact that sleep is the foundation of mental health, physical health, and performance. Helix understands that everybody's sleep needs are slightly different. So if you go to their website, you can take a brief quiz and that quiz will ask you questions such as, do you sleep on your back, your side, or your stomach, maybe you don't know, which is fine, you can simply answer, I don't know, or do you tend to run hot or cold during the night. He looks

to take those answers and then matches you to a mattress that's ideal for your sleep needs. So for me, it matched me to the dusk of the USK mattress. And I've been sleeping on a dusk mattress for over two years now, and my sleep has been better than it ever was previously. So if you're interested in upgrading your mattress, go to helixleap.com slash huberman, take their brief two-minute sleep quiz, and they'll match you to a customized mattress for you.

You'll also get up to $350 off any mattress order and two free pillows. They have a 10-year warranty, and you get to try out their mattress for 100 nights risk-free. They'll even pick it up for you if you don't love the mattress, but I think you will. I certainly love mine. Again, if you're interested, go to helixleap.com slash huberman for up to $350 off and two free pillows.

Today's episode is also brought to us by HVMN ketone IQ. Ketone IQ is a ketone supplement that increases blood ketones. I want to be very clear that I like most people. I've heard of the ketogenic diet, but I like most people do not follow a ketogenic diet. That is, I'm not in ketosis. However, most people don't realize that you can still benefit from increasing your blood ketones, which is what HVMN ketone IQ does. I take ketone IQ prior to doing really focused cognitive work.

So I take it once in the afternoon, anytime I'm going to prepare for a podcast or do a podcast or if I'm going to do some research or focus on a grant, anything that requires a high level of cognitive demand. And that's because Keyton's are the brains preferred use of fuel even if you're not following a ketogenic diet. I sometimes also use Keyton IQ prior to workouts, either resistance training workouts or endurance

workouts, such as running. Again, that's because ketone IQ by raising blood ketones is really a brain fuel. If you're interested in trying ketone IQ, go to hvmm.com and use the code Huberman to get 20% off. Again, that's hvmm.com and use the code Huberman to get 20% off. Today's episode is also brought to us by Roka. Roka makes eyeglasses and sunglasses that were designed with the biology of the visual system in mind.

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 challenges for you to be able to see clearly throughout the day. So for instance, when you go from a shady area to a well lit area, your brain and eyes have to make a bunch of different adjustments that eyeglasses of the conventional type don't always compensate for. Roca eyeglasses and sunglasses compensate for those sorts of changes and all the sorts of changes that your visual system has to contend with, so you always see things with

crystal clarity. The company was founded by two all-american swimmers from Stanford, and initially their eye glasses and sunglasses were designed for sports performance. And indeed, all of their eye glasses and sunglasses can be used while running, while cycling, they won't slip off your face if you get sweaty, they're extremely lightweight, but they also have an enormous number of varieties of eye glasses and sunglasses that are designed to be worn at work or to dinner. So they have the sort of classic performance eyeglasses where it makes you look like a cyborg. If you like those, they also have more conventional

aesthetics that you'd be comfortable wearing pretty much anywhere. If you'd like to try Roka eyeglasses or sunglasses, you can go to roka.com. That's roka.com, enter the code Huberman to save 20% off your first order. Again, that's roka.com, enter the code Huberman at checkout. Okay, let's talk about hair. And in researching this episode by talking to experts in the

biology of hair and the stem cells that exist in all of us that give rise to our hair growth and the pigmentation in our hair. And in talking to experts who understand how to halt and even reverse hair loss, that there is a tremendously interesting biology surrounding hair. But there's also an incredible psychology around hair. In fact, most people who experience even marginal hair loss undergo pretty severe anxiety. Now, I confess this is not something I can relate to. I am losing my hair in certain places.

I'm 47 years old. I've got a couple of patches up front where there's very minimal hair. I think that, as we'll later learn in this episode, reflects a higher density of DHD dihydrotistosterone receptors at that particular location as opposed to elsewhere on my scalp. But keeping my hair is not something that I've fredded about much of my life.

And yet, as I was researching this episode, I remembered an anecdote from my childhood where my father told me, and I think it was because I was stressing about something. I said, I was trying to get to sleep, and he said, don't stress, calm down, and here's why. If you stress too much, it can actually make your hair fall out. In fact, I have a cousin who lay down one night stressed and woke up the next morning and all of his hair was on his pillow.

And I'll never forget that story. I think he was trying to get me to stress less. I don't know if that story made me stress less or not. But in any event, I don't know that that story is true. I'm not going to challenge the authenticity of that story. I didn't have a chance to reach out to my father and ask him to verify or not. But as we'll soon learn, it is true that our psychological well-being can impact both the coloration or lack thereof and the growth rates of our hair. That's a real thing. And the reverse is also true, which is that as hair starts to thin or fall out or change color, many people experience intense anxiety or even depression. This was not something I was really aware of. Perhaps that's just because I've always kept my hair pretty short anyway.

I was assuming that my hair started to really fall out, I just shaved my head. But that's me, and that's not most people out there. I think most people would loathe to lose their hair and in fact, given the enormous number, probably up in the high billions of dollars and euros and other currency, of course, that people invest in trying to halt a reverse their hair loss. It's clear that hair is very, very important to people.

What we know is that by age 50, approximately 50% of all men and women will have experienced significant enough hair loss that they start to notice it. And a large percentage, up to 85% of those people will experience some sort of anxiety that leads them to go out and try and either halt or reverse that hair loss. Now, why at age 50? Well, an important point arises from that, which is that the hair loss is not occurring between the 49th and 50th birthday.

Hair loss is ongoing from about age 30 to age 50. It's only by age 50, however, that about 50% of people out there start to notice that hair loss. And this is typically because they'll, you know, they'll be in a bathroom or looking in a mirror, and the lighting will be bright enough that it permeates the outer boundary of their hair, and they'll notice that their hair is thinning in a particular location. That's usually how the sort of thing happens.

So again, our psychological states can impact our patterns of hair growth or loss, and of course, patterns of hair growth, but more typically hair loss and hair grain can really impact psychological state. So this is a subject that people take intense interest in. And today we're going to talk about how hair normally grows, why it grows at the rate and for the duration that it happens to. And then as we talk about ways to intervene with that hair loss, those biological mechanisms will come up because they really provide a nice framework

for explaining why certain treatments work more or less well, or why certain treatments might have certain side effects or total lack of side effects. It will also highlight a really key theme that will come up several times in today's podcast, which is that there are both mechanical and chemical approaches to slowing and reversing hair loss. Mechanical approaches would be things as simple as massaging the scalp, but mechanical changes to the scalp can cause either hair loss or facilitate hair growth. This is why things like micro-needling are so prominent in the context of trying to reverse hair loss. But again, there are also chemical approaches to trying to halt a reverse hair loss.

And this relates to the fact that the hair growth itself is strongly regulated by hormones such as estrogen, thyroid hormone, insulin-like growth factor, and that other hormones, in particular the Androgens, so things like testosterone, but mainly its derivatives, like dihydrotestosterone, are very much involved in setting the stage for hair growth by controlling how big or small that pool of stem cells that gives rise to hair growth is. So if any of the terms I just use are confusing to you, don't worry. I will make all of those very clear in a moment. It's actually all pretty straightforward and simple. And so I'd like to just start by talking about what hair is, how it grows, why it stops

growing, and why hair normally falls out. Let's talk about the biology of hair. And in doing so, I also want to talk about stem cells. Now, keep in mind that when you hear the word stem cells, you only like most people. Think about the sorts of cells that people are getting injected into their face to get rid of wrinkles or give them new skin or to give them more hair if it's injected in the scalp or into a joint to repair a joint or a muscle. Those stem cells are what we call exogenous stem cells, exogenous, meaning from outside

the body. The stem cells that we're going to talk about today are so-called endogenous stem cells, cells that we all make that can give rise to other cells. And that's really the definition of a stem cell. Stem cells are present in all of us from the very beginning of life. So when sperm meets egg, that cell, which we think of as the egg, starts to duplicate. It incorporates the DNA from the sperm and the egg, of course. It starts to duplicate, and then those cells give rise to more cells and more cells, and the ability of all those cells to replicate and create more cells are because those cells really are stem cells. Now, at some point, we are a completed body plan, as the biologists say.

We end up with a brain and a spinal cord and limbs and fingers and livers and guts and all the things that we need in order to be a functioning human being, even though we're a baby at that time, we haven't grown up. We have all the bits that we're going to have for our entire life. At that point, many of the stem cell populations disappear. For instance, past puberty and probably earlier, you don't get many more new brain cells. You get a few, but you don't get many more new brain cells because the brain doesn't have many stem cell populations, whereas other organs in your body maintain little pockets of stem cells, or in some cases many, many stem cells that can give rise to more and more

of that tissue across the lifespan. And hair is one such tissue. So if we take a look at hair, what we find is that, indeed, there are these things that we call hairs, but there are also stem cells, and those stem cells are actually what give rise to the hairs that we see on the head of our scalp, or that we see on the surface of our body. So right off the bat, you should know that every single hair that you have is there because you have a stem cell population that is giving rise to that particular hair. So let's take a step back or rather, I should say, let's

zoom in on one hair and the stem cell population that gives rise to that hair because in doing so, you're going to learn all the different components that you can tap into if your goal is to halt the loss of hairs or to replace hairs that have already been lost. So if we were to just zoom in at the level of one hair, what you would find is that that hair has what typically is called a hair root, so that's the portion below the skin. And when we say below the skin, it means that it dives down into a narrow trench, which is in the so-called epidermis, which is this outer layer of skin. It also has a shaft, the shaft is the part that grows out above the skin.

So what you see on somebody's head, or you see on their on their arm, or when you see an eyebrow, you're seeing the shaft of the hair, the root of course goes below the skin. What most people don't realize, however, is that down at the base of the root, there's actually a little cave, a little pocket. So, if you were to look at this, it would look like a little bowl, a little round area with a bunch of stuff in it right below the root. And within that little cave, there are stem cells.

There are populations of cells that have the ability to divide, we call this mitosis. It's a process by which cells can actually divide and take DNA with them and then give rise to other cells. We call those cells that divide and move out. We call those daughter cells. We call the cells that give rise to them progenitor cells. But they are effectively stem cells that give rise to what we call daughter cells. We call the cells that give rise to them progenitor cells, but they are effectively stem cells

that give rise to these what we call daughter cells. Those daughter cells then become the various types of cells that make up the hair. So when you see a hair, you're not seeing something that grows throughout the lifespan. You're seeing something that's going to be born down there in that little cave, then is going to grow.

It's actually going to stack up on top of itself, and that's because hairs are made up of a protein called keratin. There are a bunch of different kinds of keratin, depending on what kind of hair you're looking at. But these are little proteins that stack up on top of one another, and they're structured in a way that makes them pretty darn durable.

I mean, it's possible, of course, to pull a hair out, but if you've ever tried to tear a hair in particular, they care like one from the face or even a one off the top of your head, it's actually a pretty tensile, strong little thing. And that's because keratin's stack up on top of one another and bind to one another with a really strong bond. So what you end up with is a bunch of protein

stacked up on top of one another and that's the actual hair. Okay, so we've got the hair shaft, the hair root, and then we've got the stem cells down there in that pocket that give rise to the various cells that make up the actual hair. We also have down there in that little cave, which by the way is actually called the hair bulb,

if you really wanna know the technical name, because it's shaped like a bulb. We have not just stem cells, but we have cells that give rise to the pigment of the hair that create what's called melanin. Now, some people have very blonde hair, very light hair. Some people have darker hair. But everybody, unless they have what's called the albino mutation, where the hairs are truly white, they lack all melanin. And it's a pretty rare condition, although it does happen. Most people have some degree of melanin in their hairs because there are little pockets

of melanin-producing cells, melanin is just a protein, that essentially gets injected into the keratin, into the hair, and it gives it its darker color. Now there are a couple other components about the hair that you need to know about, especially if you're interested in reversing hair loss or reversing grain of hair. One of those components is a little gland. So next to every hair root within the dermal layer of the skin, so this is below the epidermis, there is a gland called the sebaceous gland. And the sebaceous gland makes oily stuff and the oily stuff is called sebum. I don't know what the name is, or evokes something kind of gross,

but sebum is actually really cool and really important. The sebum gets injected or seeps rather into the area right around the hair as the hair starts to approach the surface where it goes from essentially root to shaft. And the sebum does two things. First of all, it forms a little bit of a seal right at the place where the hair exits the skin. And that seal is very important actually for waterproofing

of your skin. So we don't often think of ourselves as waterproof because we are so accustomed to water just landing on our skin and rolling off, but that's because of some of the oily properties of our skin. And it's also true that our skin is pretty densely packed with cells, but in the absence of sebum, we would not be as waterproof as we are. Now, as I mentioned, sebum has two important properties. The other important property of sebum is that it actually is a strong antibacterial and anti-microbial. Most people don't realize this. The oils of your skin provide a lot of immune boundary so that things don't get into the

hair root or the region around it and infect our skin. So sebum, while the name is sort of unattractive, to be honest, is actually performing some essential roles both for waterproofing and for our immune system function, protecting us from various kinds of infection. We're going to return to sebum later, as it turns out, sebum is also very important as it relates to psoriasis, and as it relates to some of the fungal components that can cause hair loss.

Okay, so I just got to file that away. There's another important component of the region around hairs, which is the erector pili muscle. The erector pili muscle is a muscle that lies diagonally between that bulb portion of the hair or a little bit above it and goes up to the surface of the skin. The erector pilly muscle is a muscle that contracts when we get cold or when we get scared. So if you've ever had goosebumps, that's because the erector pilly muscle contracts pulling the skin at the surface down

around the little hair follicles, or at least where the hairs meet the surface of the skin. And so those little bumps are actually where little micro hairs reside. And the dimples between them are the dimples that occur when this erector pili muscle pulls down. Now, why would this muscle exist? And what has a couple of important functions.

One of the functions is that when it pulls down, it causes, as the name suggests, the hairs to stand up, maybe not perfectly vertical, but they, when you hear, oh, I was so frightened, my hair stood up on end, and that's because the hairs become erect. They stand up. Now, why would this happen when we get cold? It happens because when the hairs stand up,

air can be trapped between those hairs and can actually warm our body. This is not so much the case if you have very light hair on your skin. If you're a very hairy person, this is going to be a more robust aspect of your physiology. And yes, this is why dogs like huskies can go out in the snow and still remain warm. When they get cold, their hairs actually stand up a bit on end because the contraction of these erectorpele muscles, trapping air in there and then their body warms the hair, trapping the hair, and it's probably they've got a blanket on made by the interface between the hair, the air, and their skin. So just to recap, all the components of hair and the different things around it that are going to be relevant for understanding how to replace hair that's lost.

We have the hair itself, which has the shaft that sticks out over the skin, it goes a little bit into the skin, but basically sticks out over the skin. We have the root portion, which goes down into the skin, it goes through the epidermis and into the dermis, then we have this bulb-like region down at the bottom. Down at the bottom of that bulb, we have stem cells that actually give rise to the actual hair and we have pigmenting cells that pigment that hair. In addition, and this is very important, there are capillaries that go into that bulb region down at the bottom of the hair, and that can serve and support the stem cells, the melanin-producing cells, which are called melanocytes. The melanin-producing cells and the stem cells get a lot of blood flow that allows them

to keep providing new hair, or the proteins that make up hair, and the pigment that goes into those hairs. Those little capillaries deliver not just nutrients and things of that sort into those hairs. And those little capillaries deliver not just nutrients and things of that sort, but they also deliver oxygen. Because it turns out that the whole process of growing more hair is a very active process. Now, as soon as you hear oxygen

and you hear that the growth is an active process, that's a cue to why so many of the stories around how to keep your hair and regrow hair involve statements like, don't wear a hat. how to keep your hair and regrow hair involve statements like, don't wear a hat, it'll make your hair fall out. Or if you want your hair to grow back, don't wear hats, or massage your scalp, or increase blood flow, or why some people will suggest that people take peppermint oil,

for instance, or menthol type oils of different kinds, and massage them into the scalp, things that make the scalp tingle, or there will be light therapies designed to what? To increase blood flow to the scalp. The whole rationale there is that you're trying to increase blood flow to the stem cell and the melanocyte populations that support the hairs and that actually create the hairs. Now whether or not those approaches work, we'll touch on a little bit later.

I'll just give you a little bit of a hint right now, which is that while no single one of those approaches that I described is known to regrow hair in a very robust way, because of the requirement for oxygen and nutrients, and because it's such an active process for the stem cells and melanocytes to grow and darken the hairs that grow out of your skin. It is true that manipulations or treatments that increase blood flow to those regions can at least slow the loss of hair or can even extend the duration over which hairs continue to grow. So if you've heard things like, don't wear a hat if you want to maintain your hair or

massage your scalp if you want your hair to grow. So if you've heard things like don't wear a hat if you want to maintain your hair or massage your scalp if you want your hair to grow faster, in some sense that's true, but none of those manipulations on their own is going to robustly enhance the rate of your hair growth. Those things are designed to be done in conjunction with some other treatments that have been shown in many, many clinical studies to increase the rate and duration of hair growth. So now you have in mind a picture of what's happening at the level of individual hairs. And if you're anything like me, you're probably thinking, wow, there's a lot going on down there, just below the surface of the skin. And indeed, there is.

But really the things to think about are that stem cell population that actually give rise to the hair proteins, so that actually create the hair. The melanocytes that darken that hair, they give it pigment. That sebaceous gland and the oil sebum that provides some important antimicrobial and other properties to that general region. And that erector pili muscle. That erector pili muscle, as I mentioned earlier,

is important for creating goosebumps. And it's important for keeping huskies warm in cold environments, but it's doing some other really important things creating goosebumps. And it's important for keeping Huskies warm in cold environments, but it's doing some other really important things as well. And we'll talk about those as time goes on in this episode. Right now, what I want to do is just talk for a moment about how hairs actually grow and why they grow the way they do.

This is extremely important toward understanding hair replacement and slowing hair loss. There are three basic phases of growth of a hair. The first phase is the phase in which the stem cells down in that bulb give rise to the cells that make up the proteins of the hair. The actual growth of the hair. Keep in mind that the hair is actually growing from the bottom up. You might think, of course, it's growing from the bottom up.

Everyone knows that. But a lot of people think that the hair starts growing right at the surface of the skin. That's not the way it works. The hair is actually growing from deep within the root and stacking up and then eventually extends out across the top of the skin. That growth phase is called the antigen phase, ANA-GEN. And this for some people will ring a bell,

because if you've ever been interested in weightlifting, or even if you're an endurance runner, you'll hear about things that are anabolic, that promote growth, so anna of growth, or catabolic, that promote breakdown. So the first phase of hair growth is calledabolic that promote breakdown. So the first phase of hair growth is called the anogen phase. And it's a period of varying duration, depending on which hair in the body we're talking about.

So the anogen or the growth phase for hairs on the head, as I mentioned earlier, is anywhere from two to eight years. For most people, it's going to be about six years. What this means is that if we were to just not cut our hair, just let our hair grow for two to eight years, that hair would eventually grow to a length that it was at its maximum and then would stop growing. So we can say that the antigen phase of hairs on the scalp

is two to eight years, right? The duration of the growth phase. Contrast that, for instance, with the duration of the antigen phase for hairs of the eyebrows. The hairs of the eyebrows grow about 4.2 millimeters per month. Believe it or not, people have measured the sort of thing. Now, that's an average. So some people are going to have eyebrows

that I'm grow much longer per month. I'm somebody who, for instance, has mostly the same length eyebrow hairs, but every once in a while, I get one of those eyebrow hairs that really seems to be heading off my head, it really wants out of there. And so it's much longer than the rest. What does that mean? Does it mean that it grew faster?

Maybe, but chances are the stem cell population in that particular eyebrow follicle for that one eyebrow hair is longer than it is for the others. This is really important. I'm trying to illustrate two principles at once here. The first principle is that different hairs on your body, including the hairs on your scalp, have a growth phase of different duration. This is why the hairs on your head can grow very hairs on your scalp, have a growth phase of different duration. This is why the hairs on your head can grow very, very long, because they have a very long antigen or growth phase.

And the hairs on your eyebrows will only grow for a few months before they actually fall out. And then have to undergo replication of the stem cells to give you new eyebrow hair to then grow. What's important here is not just that there are differences in the duration of the growth phase, but rather that the rate of hair growth is not something that tends to differ

within a given body region, right? You'll hear people say, oh, my hair growth is really, really fast. Other people will say, oh, my hair growth is really, really slowly. That is probably not the case. Well, there could be slight differences in the rate of growth. That is the addition of more keratin to the actual hairs.

So creation of more hair more quickly. Almost certainly what's happening is that the duration of the antigen phase in some people is just much longer than it is in other people. And we don't realize this. And we tend to think more in terms of how fast hair grows, because if you were to just look at somebody's hair, you'd say, oh, you know, they're all more or less the same length.

I mean, some people's bangs are shorter than the back because they cut them, but if they were to just grow their hair, you'd say, oh, it's all more or less the same length. But if we were to zoom in with a microscope, we would see that there are a lot of hairs down there in between the other hairs that are very, very short, or even tiny, tiny, tiny. And those are coming in as the other ones are finishing their antigen phase. Okay? So that's the antigen or growth phase. After the antigen phase, comes the catagen phase. Again, this resembles the word catabolic or the breakdown phase.

During the catagen phase, the hair is actually receding not from the top down to the skin surface and then into the root, but the other way. It's actually receding from that bulb region up toward the surface. And that catagin phase is going to also be of different duration, depending on which area of the body you're in, and it will vary a little bit depending on who you are, meaning from person to person. We'll talk about the influences on the antigen and catagen phase in a moment.

Why is it important that it actually recedes from the inside out? Well, that's important because as it does that, there's actually a change in that bulb region down below. Because normally there's an interface, there's a conversation that's occurring between the stem cell population, the melanocytes, and the hair itself, and they support each other. And remember,

there's blood vessels going into that area, or rather, capillaries that are feeding that area as well. After the catagin phase comes the telogen phase, which means rest. The telogen phase is a period in which no new hair proteins are being added by those stem cells. During that collagen phase, that bulb down there at the bottom, instead of being nice and oval and having a lot of space in it with all these different things like stem cells, starts to pinch off from the little tube that comes down from the surface of the skin that normally would have a hair in it.

It starts to pinch off, and at some point, many hair follicles pinch off that bulb region, and it recedes and dies. And when it recedes and dies, the stem cell population and the melanocytes go with it. In other words, there is no longer a population of stem cells to give rise to more hair after that tealogen phase. And there's no longer melanocytes to pigment the hair. And in fact, the hair isn't there anymore, so there's no hair even to pigment, after that tealogen phase. Unless it's a hair of a particular type,

such as the hair on your scalp, which can then re-enter the cell cycle and get back into an antigen phase and regrow more hair from stem cells. So there are three critical stages of the life cycle of a hair that are relevant to today's conversation. There's the antigen phase during which the hair grows. There's the catagen phase during which the hair

actually starts to recede and die. The protein is actually disappearing from the bottom up. And then we have the tealogen phase, which is the phase in which the stem cell population is what's called the semi-queasant, semi-quiet, or completely cohesant, where it's not active at all. Those three phases make up the life cycle of a hair, keeping in mind that for some hairs they can re-enter the life cycle and go back into the antigen phase if there's stem cells there and if

there is oxygen there and if there is sufficient blood support and and this is a very important and if there are the appropriate hormonal signals to support growth and there is a reduction or an absence in the hormone signals that actually trigger that tillagen phase. I make this point now because much of the rest of today's discussion is going to focus on why particular hormones, such as dihydrotestosterone, cause hair loss, and why inhibiting things like dihydrotestosterone can support the preservation of hair that you have and the regrowth of hair. And to make a long story very short, and then we'll get into some additional details that

are relevant, and then I hope you'll stick around to listen to, dihydrotestosterone, which is a derivative of testosterone, causes changes in that bulb region where the stem cells reside, it shortens or halts the antigen phase of hair growth, and it extends and promotes the catagen and tealogen phase. So when we hear that, oh, you know, dihydrotestosterone makes your hair fall out or estrogen makes your hair grow, there are real chemical, or we should say,

biochemical legitimate reasons as to why that is, but it all comes back to this three phases of hair growth. The antigen growth phase, the catagen catabolicabolic or hair loss phase, and the tealogen phase, which is a resp period in which the hairs can either come back if it reenters the antigen phase or maybe it's over for good. Hormones are the accelerator and the break on each one of those phases. I'd like to take a quick break and acknowledge one of our sponsors, Athletic Greens. Athletic Greens, now called AG1, is a vitamin mineral probiotic drink that covers all of your

foundational nutritional needs. I've been taking Athletic Greens since 2012, so I'm delighted that they're sponsoring the podcast. The reason I started taking Athletic Greens and the reason I still take Athletic Greens once or usually twice a day is that it gets to be the probiotics that I need for gut health. Our gut is very important. It's populated by gut microbiota that communicate with the brain, the immune system, and basically all the biological systems of our body to strongly impact our immediate and long-term health.

And those probiotics and athletic greens are optimal and vital for microbiotic health. In addition, athletic greens contains a number of adaptogens, vitamins and minerals that make sure that all of my foundational nutritional needs are met, and it tastes great. If you'd like to try athletic greens, you can go to atlettegreens.com slash Huberman, and they'll give you five free travel packs that make it really easy to mix up athletic greens while you're on the road and the car on the plane, etc. And they'll give you a year supply of vitamin D3K2. Again, that's at lettagreens.com slash human to get the 5 free travel packs and the year supply of vitamin D3K2. So now you have in mind the anatomy of the hair and the area from which it grows and the stem cells, etc. In fact, there's

capillary innovation delivering oxygen and blood flow to the stem cells that et cetera. In fact, there's capillary innovation delivering oxygen and blood flow to the stem cells that give rise to the hair, and that there are these three critical phases of hair growth, antigen, catagen, and tealogen. Now let's talk about the accelerators on hair growth and the breaks on hair growth. There are many accelerators on hair growth, but the first one that I really want to underscore

is blood flow itself, which equates to the delivery of nutrients and oxygen. This is very important and it explains a lot of the treatments for halting and reversing hair loss. For instance, one of the longest standing treatments for halting and reversing hair loss is so-called monoxidil. Monoxidil, sometimes also referred to by the brand name Rogain, was actually a drug that was developed to treat hypertension. So this is a cardiac drug that lowers blood pressure and it does that by causing vasodilation. It allows more blood flow not just to the hairs on your scalp but to hairs everywhere

on your body. And indeed most people don't realize this but monocidil won't just slow the loss of hair from your scalp. It is also effective at slowing the loss of hair elsewhere in your body. How does it do that? Well, you now know, one of the major ways it does that, it does that by extending the anagen phase. So it basically makes that phase a bit longer.

It doesn't make it much, much longer, which is why for most people who are losing their hair quickly or who have already lost their hair, Monoxidil alone is not going to be its sufficient treatment. However, Monoxidil has been shown to be effective at slowing rates of hair loss and people that are starting to experience some hair loss, all get into dosages and things of that sort a little bit later. But right now, I just want to really focus on the logic of why people would take this drug, which is lowering hypertension at all as it relates to hair loss, right? That might seem like kind of crazy until you understand

the anatomy and the growth of hairs, which you now do. So that's what Menoxidil is doing. It's creating more blood flow to the hairs, which because Monoxidil does have this positive effect, most people would like to slow their rates of hair loss on their scalp anyway, it tells you that blood flow and delivery of oxygen and other nutrients from the blood is pretty critical if not very critical for the support of the hair growth cycle itself. Now, again, we haven't talked at all for the support of the hair growth cycle itself. Now, again, we haven't talked at all about the sorts of chemicals or the signals within the body, such as hormones that actually direct the growth of hairs. Here, we're just talking about a

mechanical change, allow more blood flow to the region and thereby extend the antigen phase, which is exactly what happens with manoxidil. Now, menoxidil does have other effects, and this is why dosing a menoxidil becomes a little bit complicated and can be a little bit tricky to troubleshoot. It can greatly lower blood pressure or lower blood pressure just a little bit depending on how sensitive somebody is to that particular drug.

So oftentimes physicians will start people on menoxidil dosages that are very low. Ideally, that would be the case, and then ratchet it up in order to figure out where the minimal effective dose or the kind of critical threshold is beyond which they start experiencing some pretty uncomfortable side effects, such as swelling of the ankles or headaches

or dizziness. These things can't happen with the use of Rogaine aka monoxidil. Now, monoxidil has also been associated with increases in the hormone prolactin. Prolactin is a hormone that's released from the pituitary. It is a hormone that acts also as a bit of a neurotransmitter like many hormones, and it tends to be antagonistic or in opposite to dopamine. So dopamine is a neurochemical, it's actually a neuromodulator, meaning it modulates

the activity of a bunch of neural circuits in the brain. It also controls the release of various hormones in the body. Dopamine is almost always associated with states of motivation, pursuit, and drive. It has a little bit of a kind of feel-good element to it, which is why a lot of people think dopamine is associated with reward and pleasure, but it's really about energy, motivation, and drive. Dopamine and prolactin are, as I mentioned before, antagonistic to one, they're in sort of a push pull. So people who take monoxidil, especially if they're very sensitive to it, or they take dosages that are too high, will experience increases in prolactin that in turn can cause

things like reductions in libido, reductions in overall feelings of well-being, apathy, and in some cases where the elevations in prolactin are more extreme, they can experience, for instance, increase in male breast tissue, gynecomastia, or even small bits of milk let down, things of that sort. In women who take monoxidil, this side effects

are much like the ones experienced in men, so there can be swelling, edema of the tissues, because if you get too much vasodilation and too much lowering of blood pressure, that's not good, headaches, dizziness and so on. So dosing a monoxidil is really important. If somebody's going to use monoxidil in order to try and slow or reverse hair loss, and

again, it mainly is going to be used to slow rates of hair loss, not to actually reverse hair loss. The really key thing is to get that dosage right. So the ranges of monoxidil that you'll see suggested and that people use out there are vast. And I should also mention that there are two major routes by which people get monoxidil to the hair follicle. One is to take it systemically as a pill

where it goes into the general circulation. The other is to take it topically as a cream. There are prescription and non-prescription forms of monoxidil, just to further complicate things. But the ranges of oral monoxidil that you'll see out there and that people take, range anywhere from 0.25 milligrams, all the way up to five milligrams per day.

So that's an enormous range. It's like a 20-fold range. The topical monoxidil is also found in various concentrations. The typical concentration is going to be a 5% concentration that people will use once per day. Topical treatment with monoxidil at 5% concentration is thought to just stay at the scalp,

but we now know that it can go systemically, it can get into the general bloodstream. Why that issue make complete sense to you because when you put something on your scalp, I've already told you these little pits, these little tubes that go down to those bulb regions below the skin that have direct access to the blood supply. So when you massage something into your scalp,

it not only has the opportunity to get into your general circulation, it often does, especially if it's something that's very water soluble, and that way you can get into the capillaries and into the general bloodstream, although topical treatments, of which we're going to discuss a number of them today, don't tend to get into the general circulation as robustly as taking something by way of pill

or capsule. Okay, so monoxidil works by way of increasing blood flow to the stem cell niche below the hair. The dosage ranges of the oral monoxidil are tremendous, 0.25 milligrams all the way up to 5 milligrams, once per day. The dose of range of the topical solutions tends to be a little bit more confined, typically it's a 5% solution and it's recommended that people use it one time daily, maybe twice daily. It's also important by the way, if you're going to take this route, that you actually leave that solution on the scalp for three to five minutes. This is important and should make complete sense as to why it's important. You can't just rub the stuff into your head and then rinse it off and expect it to be absorbed.

It actually needs to seep down into those hair follicles and access the niche. How do people arrive at the correct dosage for monoxidil? Well, for better or for worse, really. In some cases, it's accomplished by finding out that you have an unwanted side effect, like dizziness or swelling of your ankles or edema or I would hope this wouldn't be the case, but something that suggests there's hyperprolactinemia. You could get a blood test to measure your prolactin or you perhaps notice a drop in libido or some lethargy. These sorts of things that are common to reduce levels of dopamine, increase levels of

prolactin. I would hope that if people are working with a physician or if they're not in taking monoxidil, that they would start with the lowest possible dose. So for oral monoxidil, that would be 0.25 milligrams and then increase it as needed, rather than jumping in right at 5 milligrams. oral monoxidil that would be 0.25 milligrams and then increase it as needed rather than jumping in right at 5 milligrams because some of those side effects in particular the fluid retention and the hyperprolectinemia can be pretty uncomfortable and can disrupt a lot of aspects of life that most all of us consider desirable.

Okay, so we're really focusing right now on treatments that relate to the critical requirement for hair stem cells to receive blood flow in order to receive oxygen and nutrients to get the hair to grow. And that's really what monocetyl is about. It's also what all of those anecdotes you hear are all about like massaging the scalp, or putting red light on the scalp. Although red light might do some other things, in general, heating or lighting of the scalp or massaging of the scalp is really designed to increase blood flow to the scalp.

The reason monocetyl works at all is because it is going to increase blood flow around the clock, and that's because people are taking it topically and it's seeping into the general circulation, or at least as stings, somewhat restricted to the hair cell niche, or they're taking it early, and it makes it to that hair cell niche below the follicle. When we massage our scalp, however, that's a transient thing. You know, I can massage my scalp right now.

I'm no doubt increasing blood flow to certain areas, I'm probably decreasing blood flow to the areas I'm pushing down on, but it's all temporary. I don't know many people that can massage their scalp enough during the day or long enough during the day, rather that it would sufficiently increase blood flow. With that said, it is clear that increasing blood flow to the scalp by way of reducing hypertension,

which is effectively accomplished by broadening, by expanding the blood vessels and capillaries, is an effective way to at least hold on to the hair that you have. Is it going to completely halt hair loss? If you have a strong genetic bias towards hair loss, no. Is it going to reverse hair loss? Very unlikely that it will, but it can slow hair loss or even maintain the hair that you have.

So, if we were to take a step back and ask ourselves what other sorts of drug treatments are out there besides monoxidil that increase blood flow and that might increase the rates of hair growth or more likely increase maintenance of hair that one already has by increasing blood flow to the niche. And nowadays there are more and more doctors who are familiar with this requirement for blood flow understand the mechanisms by which monoxidil works, and understand the vast desire out there for people to hold onto the hair they have and regrow hair, and they're prescribing things like low dose to dallophil. So 2.5 milligram to 5 milligram to dallophil.

To dallophil was initially discovered as a drug to treat prostate health. It was a drug that we now know can increase blood flow to the prostate and thereby offset some of the issues associated with an aging prostate. Higher doses of tidalophil, sometimes also referred to as the by its brand name, which is Cialis, are used to treat erectile dysfunction, but at the dosages that are used to increase blood flow to the prostate and that now a number of doctors are using to treat erectile dysfunction, but at the dosages that are used to increase blood flow to the prostate, and that now a number of doctors are using to increase blood flow, not just to the prostate, but to all regions of the body,

including the scalp, such as 2.5 to 5 milligrams to dallophil. So this is something that I think deserves attention because it falls under the umbrella of increasing blood flow to the hair stem cell niche in order to maintain hair. It is not something that most doctors are going to be familiar with as the way to reverse hair loss because it won't do that. But the use of low dose to dialophil to slow rates of hair loss is very much in a logical mechanistic sense, exactly the same as the logic of using manoxidil to

slow rates of hair loss. It's all about increasing blood flow to support the stem cell niche below the hair follicle. The critical requirement for blood flow oxygen and nutrients to the stem cell niche is also why you hear a lot nowadays about the use of PRP, platelet-rich plasma for trying to offset hair loss or even reverse hair loss. We're going to do an entire episode about PRP. It is pretty controversial in certain circles and well accepted in other circles. A couple of key things to understand about PRP. First of all, it is being used in multiple tissues for different purposes in different clinics.

So for instance, board certified physicians in the United States, Canada, and Europe are doing PRP injections into ovaries to try and expand the number of healthy follicles and eggs so that people can conceive later in life, or even earlier in life if they don't have many follicles. People are getting PRP injections into their joints in order to try and support joint health. People are getting PRP injections into their joints in order to try and support joint health.

People are getting PRP injections into just about every tissue you can think of. However, PRP, despite what you may have heard, is not stem cells. Somebody tells you they're injecting stem cells. They're either outside the US, Canada, or Northern Europe, or they're injecting something else. So you want to really look into that. The safety issues there are subject, totally deserving of an entire episode. I'm not necessarily opposed to the future of stem cells

as a treatment, but keep in mind that stem cells are cells that can give rise to lots of other cell types and they are cells that divide and replicate. And there's a name for that when it happens in the adult body when you don't want that. And that's called cancer. Tumors are overproduction of cells from stem cells when those stem cells ordinarily should be quite essence.

Okay. So keep in mind the difference between stem cells and PRP. PRP, platelet which plasma, again, is legal in the U.S. and many other places because it involves drawing somebody's blood, spinning it down at a particular speed, which separates out different components within the blood, then taking the platelets and re-injecting those in a solution back into the person's body. So platelet-rich plasma, or PRP, is platelet-enriched plasma from that person. But the basis of PRP is really to encourage nutrient delivery

to a particular region in the body using somebody's own platelets because those platelets are enriched for various nutrients. So people are getting PRP injections into their scalp. Those are not stem cell injections. So those are PRP injections into the scalp. With some moderate success, these are very expensive treatments. They tend to be transiently successful. I'm sure there are people out there who are going to say PRP worked fabulously well for me. That meant be the case. I'm not going to dispute that and I'm happy for you.

Although there are not sufficient clinical data to suggest PRP as a treatment right now, especially given the cost, many thousands of dollars, many, many treatments. It's also the case that the PRP injections, when they work, might work for reasons independent of the platelets. What do I mean by that? Well, soon we're going to talk about a different type of treatment, which is a mechanical manipulation of the hair follicle, typically on the scalp, because that's typically where people want to regrow hair.

I don't know many people who are trying to maintain or accelerate or regrow their back hair for instance. They might be out there but I don't think there are a lot of them or their leg hair for that matter almost always it's gonna be scalp hair and one way that people are doing that is through mechanical stimulation of the hair follicle and the stem cell niche using what's called micro-needling micro-needling as the name suggests is taking a bunch of little needles, either in a little stamp, so a little square or nowadays typically it's a roller. So it looks like a paint roller except it's got tons of little needles in rows all over that roller.

Those needles range in length from half a millimeter to 2.5 millimeters, okay, millimeters. And one rolls that over the scalp. And if you're thinking, ouch, that probably hurts. Indeed, it can hurt a little bit or a lot depending on the thickness and the length of those needles. Micro-needling has been shown to do two things. It has been shown to reactivate semi-quiescent populations of stem cells that are in that tealigen phase, putting them back in antigen phase, and thereby stimulate more hair growth. It is also, and this is, I think, the best use of micro-needling. It has also been shown to be a very effective augment for some of the hormone-based hair

regrowth tools and pharmacology that we're going to talk about in a few minutes. So micro-needling and PRP have something very critical and common, which is the needle, the actual injection into the skin. And for those of you that are hearing this and thinking, why would disrupting the skin with needles actually support hair growth or regrowth? Wouldn't that just damage the follicle? Well, this gets into some of the, I think, interesting, if not fascinating aspects of our biology, which is that all of the cells in our body really can respond to both chemical and mechanical cues.

And when we hear needle injected in the skin, we think, ah, that must just be damaging everything, causing all sorts of inflammation. But it turns out that low levels of inflammation caused by things like micneedling or PRP injections, or even the introduction of any kind of fluid. For instance, saline fluid injected into a region can cause changes in the cells in that region, causing, for instance, stem cell populations that we're waning to reactivate

again, causing tylogen phase follicles that have melanocytes and stem cells that are dying off but not completely gone to reenter the cell cycle. So microneedling procedures, PRP injections, things like monoxidil, they all kind of center around this same general theme of increasing blood flow,

increasing oxygen delivery of nutrients, or in the case of micronealing Increasing inflammation just enough at that local site that certain cascades of biological function that relate to proliferation of stem cells or maintenance of stem cell populations are kicked off It's sort of like reminding the cells in that area that they need to stay alive in order to replenish whatever is lost. So sometimes a wound can actually induce some healing, although I do want to point out that the micro part of micro-needling is absolutely key. And this should be obvious to you when you think about scars.

I don't know about you, but I've never seen a scar with hair growing out of it. Or if there was, it was probably like one hair. But if you've ever seen a scar, if someone had their appendix out or someone had a brain surgery, you see that scar because there is no hair growing out of it. So the micro portion of microneedling is extremely important. We are not talking about causing significant damage

to a tissue in order to activate that stem cell population. We're talking about causing significant damage to a tissue in order to activate that stem cell population. We're talking about causing micro damage and micro levels of inflammation to stimulate growth. For those of you that are interested in using micro-needling or micro-needling in combination with chemical treatments like monoxidil or some of the other treatments we'll talk about in a little bit like finasteride and caffeine. Yes, believe it or not, caffeine is being used to regrow hair. Very interesting. Get into that in a moment. asteroid and caffeine. Yes, believe it or not, caffeine is being used to regrow hair. Very interesting. Get into that in a moment. But if you're interested in using micro-needling

alone or in combination with some of these other treatments, there's a wonderful review that was just published this last year. Wonderful because it's very comprehensive. Not so wonderful, not to the fault of the authors because most of the studies out there on micro-needling are not superb. There are ways of gauging the strength of a study, mainly related to their duration, whether or not there were control groups, et cetera. But the review itself is excellent. The title of the review is micro-needling

and its use in hair loss disorders, a systematic review. We will provide a link to this in the show note captions. And this review did a very good job of highlighting both the strengths and drawbacks of the various studies looking at micro-needling. It also explored the use of micro-needling in both men and women and of various ages. And it does appear to be the case,

the micro-needling shows some positive benefit in both men and women regardless of age, especially when used in combination with the various other treatments that we're talking about. I was also able to glean from this review and some of the papers described within it that needle lengths of about one millimeter to 2.5 millimeters seem to be more effective

than shorter needle lengths. So if you're scared of the needles and the needle lengths, keep in mind that done properly, micro-needling shouldn't be too painful. Some people experience a little bit more pain than others, but it's not considered a very painful procedure. It is, however, a procedure that can cause some bleeding of the scalp, and that bleeding of the scalp can be very apparent, especially if it's in the front of the head, as opposed

to in the top of the head, and hidden by some hair, or if you're already quite bald in a given region. So keep that in mind, I suppose one could wear a hat or a wig or something of that sort if they were really self-conscious about it. But the micro-needling itself is causing a physical disruption to the scalp, some degree of bleeding, inflammation, and again, all of that is part of the process by which micro-needling can actually improve hair growth. And of course, there's healing that occurs of the bleeding and the damage to the follicle.

This is a transient thing, but understanding the cosmetic implications in the short term, as well as in the long term, is certainly worth knowing. One thing that's very clear is that the combination of microneedling and monoxidil treatment together is far more effective than either of those treatments alone. In addition, the combination of microneedling and monocidil has been shown to be effective in recovering what are called dead zones. So these are regions of the scalp that are either completely bald or mostly bald, for which there is essentially no stem cell population there, and the combination of monocidil plus

microneedling is somehow able to recover those stem cell populations and allow new hair to grow, although the growth of that hair in those dead zone regions can take a very long time, 30 to even 50 weeks. Neither monoxideil treatment alone nor microneedling alone has been shown to be effective in recovering these so-called dead zones when those treatments are done separately. So this, I would say, is a strong reason to consider combining micro-needling and monoxidil, as opposed to just doing monoxidil or just micro-needling. I should also mention that monoxidil treatment, if you pursue it, is likely something that you are going

to have to do for the rest of your life if you want to hold on to the hair growth that you obtain with monoxidil, or if you want to maintain the hair that you are already obtain with monoxidil, or if you want to maintain the hair that you are already maintaining with monoxidil. Some people have been successful in taking monoxidil, maintaining some hair growth, or even stimulating some hair growth, and then coming off monoxidil, but most everyone who goes on monoxidil has to stay on monoxidil because when they cease taking monoxidil, even if they're

doing other treatments, they lose the hair that they gained with manoxidil, even if they're doing other treatments, they lose the hair that they gained with manoxidil. So that is an important consideration. The decision to go on manoxidil is likely a decision to be on manoxidil for the rest of your life. I'd like to just take a brief break and thank one of our sponsors, which is Element. Element is an electrolyte drink that has everything you need and nothing you don't. That means plenty of salt, sodium, magnesium and potassium, the so-called electrolytes,

and no sugar. Now, salt, magnesium and potassium are critical to the function of all the cells in your body, in particular to the function of your nerve cells, also called neurons. And we now know that even slight reductions in electrolyte concentrations or dehydration of the body can lead to deficits in cognitive and physical performance. Element contains a science-backed electrolyte ratio of 1,000 milligrams, that's 1 gram of sodium, 200 milligrams of potassium, and 60 milligrams of magnesium. I typically drink element first thing in the morning when I wake up in order to hydrate my body and make sure I have enough electrolytes.

And while I do any kind of physical training and after physical training as well, especially if I've been sweating a lot, and certainly I drink element in my water when I'm in the sauna and after going in the sauna because that causes quite a lot of sweating. If you'd like to try element, you can go to drink element that's LMNT.com slash Huberman to claim a free element sample pack with your purchase. Again, that's drink element LMment.com slash Huberman. So as you're probably starting to realize, there's a relationship between mechanical stimulation of the follicle and blood flow, both of which turn out to be critical for maintaining

hair and for stimulating hair growth. Not surprisingly, then, an increasingly common treatment for hair loss is Botox. Botox is the brand name for what is otherwise known as Botulinum neurotoxin. What is Botulinum neurotoxin? Well, Botulinum neurotoxin, sometimes just called Botulinum for short, is a toxin that's a bacterial toxin that serves to cut the protein that leads to synaptic vesicle release. What in the world did I just say? Well, when your nerve cells communicate with one another, they do that by way of electricity, but the electricity within those nerve cells, those neurons, triggers the release of chemicals from neurons into the synapse, the little gap between neurons.

And the release of those chemicals allows the next neuron to be chemically active, or, in some cases, it will suppress the electrical activity of that next neuron to be chemically active, or in some cases it will suppress the electrical activity of that next neuron. Botulinum neurotoxin serves to cut a protein present in neurons so that neurons cannot release the chemicals that cause other neurons to be active. This actually is pretty serious if you were to get botulinum neurotoxin injected into your muscle, you would be paralyzed because the nerves that control contraction of the muscles would not be able to control the release of that chemical onto the muscle, which makes it contract.

Botulinum neurotoxin is commonly used in what's called Botox. Botox is something most people are familiar with because people get injected in and around their wrinkles. Because many wrinkles are triggered by not just loss of tensile strength in the skin, but rather the nerves around the skin and in the skin are hypercontracted, which causes wrinkles. So for instance, I have crow's feet. I like to think that's because I've laughed a lot and smiled a lot, and it's probably also because I've squinted a lot in my lifetime. I have crows feet because the nerves there

have pinched the skin on either side of my eyes. And that's given me little creases there that are sometimes referred to as crows feet. Botox injections can be applied to the scalp in order to relieve tension of the scalp. And in hearing that, it should be obvious why Botox is being used to try and offset hair loss. It's decreasing the squinting, if you will,

or the tensile nature of the scalp skin so that more blood flow can arrive at that stem cell follicle area. So Botox treatment to the scalp is actually becoming pretty common. There are a couple of requirements with this Botox treatment. First of all, it has to be done by somebody who's really skilled. There are numerous images online and websites online of so-called Botox fails,

where people have gotten too much Botox or the injections have been done too deep or not at the correct locations on people's face or scalp. And it can give them droopy scalp or droopy eyes. All sorts of cosmetic nightmares can occur with Botox. The second thing to understand is that Botox does eventually wear off. That botulinum neurotoxin doesn't stick around forever and provided it's done correctly at the correct dosages. It doesn't actually kill the neurons that cause that tension of the skin.

So Botox injections have to be done repeatedly. The efficacy of Botox for offsetting hair loss is not clear. There aren't a lot of large scale clinical studies on this just yet, but it does seem to be at least one reasonably safe alternative to things like Menoxidil. Although I think if one were to just want to increase blood flow to the scalp, things like low dose Tidalophilm, which doesn't seem to carry any of the side effects that Menoxidil can carry, we talked about those side effects side effects that manoxidil can carry. We talked about those side effects earlier.

That would probably be the better alternative. Botox is a fairly invasive procedure, but some people opt for Botox treatment. In fact, there is a syndrome called cutus verticus gyrata. Some of you have probably seen this. It's more typical in men, although it does occur in women. It literally means a lumping of the skin on the scalp, or gyri of the scalp. Gyri, or gyrosit, pertains to the Latin word me, so it means bump or knee.

And so anytime you hear the word gyra in neuroscience or in biology, you're talking about a bump. Sometimes see people have ridges in the back, or it looks as if the skin was pushed together, kind of like the a sharp A dog, but on the scalp. People with cutest verticus, gyrata almost always experience pattern hair loss. Now part of the reason for that

is cuticus, verticus, gyrata is also associated with some Androgen or testosterone-related hormone issues that we'll talk about in a little bit. But in addition to that, it has been shown that relieving some of those gyrata by injections of Botox to allow those folds to sit flatter A is effective. It can lead to less of those gyri, those bumps, and can improve hair growth in those regions, even if those people don't take on any additional treatments to address the hormone issues.

So, that's really how people arrived at this understanding that Botox might be a good treatment in general for reducing the kind of squinting of the scalp that can occur and the resulting hair loss in those regions. I now like to turn our attention to the chemical variables that control the duration of the growth phase of hair, the duration of that catagen phase of the growth phase of hair, the duration of that catagen phase, which is when that hair essentially recedes from the inside out, and the quiescent or semi-quiescent tealogen phase. There are a couple of key chemical players here that we should

all be aware of. First of all, the growth factor, IGF1, insulin growth factor 1, which is produced by the liver, but that receives stimulation from the brain and pituitary to be released, is a strong regulator of hair growth, and we can think of it as the accelerator on hair growth. So it does that by extending that anagen or growth phase for longer. It doesn't necessarily speed up growth, but it extends it for a longer period of time. In addition, cyclic AMP, which is part of what's called

a second messenger pathway. In fact, cyclic AMP is a second messenger, is also a key player in stimulating growth of the hair follicle. Now, cyclic AMP does many different things in many different cell types in the body. It really acts, as the name suggests, as a messenger between signals that arrive at the surface of cells

and transmitting or conveying those signals to things that happen deep within the cells such as the turning on and off of various genes. So when you hear second messenger, don't let that confuse you or overwhelm you. Just understand that the whole process of getting signals from the outside of cells into the center of cells and controlling gene expression, for instance, causing a stem cell to continue to give off daughter cells or causing a hair cell to continue growing for longer, that whole process is a bit like

a bucket brigade of handing off water or a bucket from one component to the next or a long chain. It's like an assembly line. I think that's probably the simplest way to think about it. So for sake of this discussion, IGF1 is known to increase the growth of hair by extending that antigen phase as is cyclic AMP. So those are going to be considered the accelerators, at least in this conversation. The brakes on hair growth are going to be the things that either shorten the antigen phase or that extend the catagen phase or this quiescent phase, which is the tillagen phase.

And the two major brakes on hair growth that we want to think about are PDE, which is a phosphodiesterase. Anytime you hear ACE, it's likely to be an enzyme, and TGF beta 2. So this is a particular growth factor that somewhat counterintuitively doesn't stimulate growth, it actually stimulates lack of growth or shortens growth. So with all of that in mind, and please do also keep in mind that you don't need to remember all those specific terms, just understand that there are some factors like insulin growth factor one that act as accelerators on growth and there are factors that act as breaks on growth. We can start to think about why, for instance, half of all people by age 50 start to lose

their hair. Well, they start to lose their hair because of something called Androgen-related alopecia, which translates to English, means testosterone and testosterone derivative-induced hair loss. This is true in men and women. So hearing that, you should probably be wondering the following thing. Young men have higher levels of testosterone than old men, right? Well, the answer is yes. Although some older men in their 40s, 50s, even 80s maintain testosterone levels similar to many men in their 20s, but most don't. It's a downward slope starting at about age 40. How steep that downward slope is depends.

Women too have testosterone. In fact, women have higher levels of testosterone than they do estrogen. That's right. A healthy woman has higher levels of testosterone than she does estrogen. However, women on average have lower testosterone than most men.

So they still have far more estrogen and far less testosterone than most men, but the level of testosterone that they have within their body is higher than the level of testosterone that they have within their body is higher than the level of estrogen they have. Androgens such as testosterone and its derivatives, such as dihydrotestosterone, which will be much the topic of what we're getting into next, inhibit IGF1 and cyclic AMP. Again, androgen such as dihydrotestosterone inhibit, prevent the action of IGF1 and cyclic AMP, which you just learned a few moments ago, act to extend the antigen or growth phase of hair,

which then raises the question, well, if young people, both male and female, have higher levels of testosterone than they do when they're older. Why would people lose their hair when they're older and not younger? The answer lies in the conversion of testosterone to dihydrotestosterone. Testosterone, most people have heard of, dihydrotestosterone or DHT, is made from testosterone. There's an enzyme called 5-Alpha reductase. The converts testosterone into dihydrotestosterone in both men and women. Dihydrotestosterone binds to the Androgen Receptor at five times the affinity of testosterone.

So it is the most powerful Androgen in humans. And it is responsible for a number of things that we all really want and like, such as mental vigor, physical vigor, strength, healing capacity, drive, libido, and on and on. So DHT itself is not bad. So if we take a step back and we acknowledge testosterone levels are higher in males and females at younger ages as opposed to older, but as they get older, there is more five alpha reductase activity, which is converting more of that testosterone to dihydrotestosterone and dihydrotestosterone inhibits hair growth by reducing IGF1 and cyclic AMP. Well, then we should all be aboard why it is

that by age 50, about 50% of people experience pattern hair loss. That is androgen dependent alopecia. But translated to normal English is pattern hair loss. And in a moment, you'll understand why some people lose their hair from the crown region, I'm in the back of the head or back and top of the head, whereas other people lose their hair in the front of their head, in the flanks right on either side of the midline or maybe in the midline in front all together. And that's because different people, depending on their genetic lineage, have different patterns of Androgen receptors on their scalp.

And the pattern of Androgen receptors that you inherit indeed does come from your mother's side. So this is what gave rise to the myth that if you want to know if you're going to go bald or not just look at your mother's father, it doesn't quite work that way. In fact, if you think about the logic, you should really look at your mother's mother if you want to know your pattern of Androgen receptors on your scalp. However, most women don't lose as much hair from their scalp or they have ways of covering up the hair loss in their scalp because their hair is just generally longer or they have ways of covering up the hair loss in their scalp because their hair is just generally longer

or they're using other approaches so that you never really get a clear picture of what the Androgen dependent hair loss was in your grandmother. Now, we don't want to go too far down the genetics rabbit hole because as you know, you can't select your parents anyway. But if you want to know why, for instance, I'm losing a bit of hair on either side

of the midline in the front, it almost certainly has to do with the fact that I have a higher density of Androgen receptors there, as opposed to, say, on the crown of my head, where for whatever reason my hair seems to grow thickest. Other people lose hair on the crown in the back and top, but not in the front, and some people lose it all over. Now you understand why hair loss occurs in certain regions of the body. You should also understand that the Androgen receptors on the face

are also what are responsible for beard growth. And this is where I can get a little bit tricky, but a lot of things will start to make sense if you can understand this and internalize this. If you have a high density of Androgen receptors on your face, well, then as your DHT levels go up with age, you will be able to grow a thicker and thicker beard. In fact, it is rare to see someone who can grow a thick beard in their youth, but not so much as they get older. In fact, the reverse tends to be true. So the pattern of Androgen receptors differs between the scalp

and the face and the back. Okay, on your back, you have Androgen receptors and their DHT stimulates hair growth. So if you know someone who has a very hairy on your back you have angiogen receptors and their DHT stimulates hair growth. So if you know someone who has a very hairy back or if you have a very hairy back, that means you have a high density of angiogen receptors on your back. If you have a beard and that beard is thick, well then you have a high density of angiogen receptors

on your face. However, a high density of angiogen receptors anywhere on your scalp is going to predispose those regions to angiogen dependent alopecia or hair loss in those particular regions, which is going to predispose those regions to Androgen-dependent alopecia or hair loss in those particular regions, which is going to allow us to understand why all of the rest of the treatments for halting hair loss and for stimulating hair growth, almost all of those center on inhibiting either DHT directly or 5 alpha reductase, the conversion of testosterone to DHT.

So now I'd like to discuss the ways that one can chemically adjust certain things within the hair growth pathway, things like IGF1, PDE, TGF beta, etc. in order to stimulate hair growth or halt hair loss. The first thing on this list is actually going to be pretty surprising to a number of you. And that's caffeine. We all think of caffeine as a stimulant that we drink. I certainly drink coffee in your bamaaté, the occasional energy drink, things of that sort.

Caffeine does many things besides stimulate our central nervous system and make us feel less sleepy, however. One of the things that caffeine does is it is a fairly potent PDE inhibitor. By being a potent PDE inhibitor, it indirectly stimulates IGF1. Why? Well, because PDE can suppress IGF1 and by ingesting caffeine or by applying topical caffeine ointment or cream to the scalp, you can suppress PDE sufficiently enough to increase IGF1 and increase some hair growth or at least maintain hair growth in that region. This may come as a shock. It might seem a little bit esoteric or even outside the margins of typical treatments,

but head-to-head topical caffeine application can be as effective as monocidal application without actually lowering things like blood pressure and potentially increasing prolactin and some of the other negative, let's call them negative because they are side effects of monocidal. So caffeine ointments and caffeine present in various hair treatments and creams, et cetera, is starting to become a more prominent female there. I will include a reference to caffeine and its uses for offsetting hair loss. Keep in mind that topical caffeine appointments shouldn't necessarily be applied every single day, so this is the sort of thing you might do three times a week. The concentration of caffeine and

different appointments varies tremendously. Most of the studies of caffeine on the stem cell niches, the control hair growth and extension of the antigen phase of hair growth have been performed in vitro in a dish. Although there are some clinical studies exploring this, they are not nearly as extensive in number or duration as the studies of monoxidil because this approach just hasn't been around quite as long. However, when comparing side effects of monoxidil, cost of monoxidil, comparing the efficacy of caffeine and monoxidil, I think menoxidil, comparing the efficacy of caffeine and menoxidil, I think caffeine as a topical treatment for offsetting hair loss, stands

as a pretty good choice if you're going to start exploring this pathway. And there's no reason to think that if you were to try the caffeine ointment and it didn't work for you or you didn't like it for some reason or you needed to stop it for some reason that you couldn't stop it safely because it doesn't carry all the other blood pressure related effects and prolactinemia effects that Menoxidil does. So if you look out there into the hair maintenance and hair replacement literature, you look at the treatments that are being sold. Don't be surprised to see caffeine there. And also, don't be surprised when I tell you what I'm about to tell you now, which is

no, you can't simply just drink more caffeine in order to accomplish the goal of offsetting hair loss. It is true that when you ingest caffeine, it goes systemically. However, you have so many adenosine receptors throughout your body. Those adenosine receptors and the parking of caffeine in those adenosine receptors is the main way in which caffeine exerts its stimulatory effects, making you feel less sleepy. So, it does that because then adenosine can't have its effects, which are to make you sleepy. Well, those dentists in the receptor soak up so much of the caffeine that you would ingest

orally, that very, very little would make it to the scalp and to the hair follicles at the concentrations that you would want. So that's why you have to rely on the application of these caffeine ointments about three times a week. Keep in mind that no one has really explored the dosages of caffeine in these ointments in a systematic way. We are still in the early stages of all this. But I do think it's important to mention caffeine because of the lower incidence of side effects, at least reported side effects, and the general safety margins and the head-to-head, essentially comparable efficacy with monoxidil, because monoxidil has a bunch of other issues. Now keep in mind that both monoxidil and caffeine are generally used as a preventative for

reducing hair loss over time. They are not expected and they do not as far as we know create new hair growth to any sufficient degree. If any of you have used caffeine ointments or monoxidil and observed new hair growth to any sufficient degree. If any of you have used caffeine ointments or monoxidil and observed new hair growth that was robust, please put that in the comment section. I'd be curious about those experiences, but as far as I know, and from the clinical literature that I read, there's no examples of that. One other point about caffeine, it does appear that caffeine can not only indirectly stimulate IGF1 in the antigen phase of hair cell growth by way of reducing PDE and TGF beta, but it also seems to reduce apotosis, which is

naturally occurring cell death of that stem cell niche. We've been talking a lot about the antigen or growth phase of hair. We also talked about the catagen or the recession of that hair from the inside out, but remember that third phase, the tilagen phase, where that whole bulb down at the bottom, the bulges it's called, gets pinched off and the whole thing dies and takes the stem cells off to the grave with it. It appears that caffeine can offset the death of that niche and potentially maintain the stem cell population longer, making caffeine a really good choice to think about in conjunction

with the various chemical treatments aimed at directly attacking the DHT pathway that we'll talk about next. So there's one very direct way to increase hair growth and maintain the hair that you have on your head, and that's to increase IGF1. That can be accomplished through prescription drugs, such as growth hormone and things that stimulate the release of growth hormone and IGF1. Keep in mind growth hormone is released from the anterior Pertuitary during the first hours of sleep, especially when you haven't eaten anything for the two hours prior to sleep.

And especially when you get regular bed times. Yes, this is a real thing. If you are going to sleep at variable bed times, especially if you go to sleep much later than your usual habitual bedtime, you will miss that growth hormone pulse that normally occurs in the first two to three hours of sleep. This does not mean that you need to be neurotic about getting to sleep at the exact same time every night. There's probably a plus or minus 30 minute window and it doesn't mean that you can't stay out late or have a bad night sleep every once in a while or get woken up. Your hair isn't going to fall out. My dad's story, notwithstanding, your hair isn't going to all fall out because of that. But you do want to try and get that natural growth hormone release each night. And as I mentioned, there are prescription approaches and those are growth hormone itself. And things like Cermorellin, which is a peptide that increases growth hormone.

It's actually a secreted gog. It causes the secretion of growth hormone. And thereby actually a secretedog. It causes the secretion of growth hormone. And thereby, increases in IGF1. This is well documented. Both growth hormone and IGF1, as I mentioned, are available by prescription. They are not without their side effects. So, they do cause growth of all tissues. They do increase height in children. They increase bone mass and density. They can increase mainly fat loss, not so much muscle size, but they can increase leanness and they increase hair growth. They can increase turnover of skin, they can make skin look more youthful. All these things sound wonderful. And yet,

they also have problems because they can increase growth of small tumors that normally might be eliminated. So there is an increased cancer risk with growth hormone treatments in IGF1 or anything that increases IGF1 such as sermerellen, hypermerellen, any of the peptides that you hear about nowadays. That said, a number of people are using sermerellen as an indirect way to increase IGF1 and thereby to increase hair growth. It does seem to be fairly effective in doing that, especially when done in conjunction with other treatments that we'll talk about.

But keep in mind, these are prescription drugs and they do carry their own risks. The other thing about stimulating the natural production of IGF1 is that as its name suggests, insulin growth factor 1, it is insulin dependent in many ways. If not for its secretion, then for its action at the hair follicle and stem cell. So one of the things you really wanna pay attention to is to avoid being insulin resistant, or rather you want to try to be insulin sensitive. So if you're carrying a lot of excess body fat,

if you're obese, or if you have type two diabetes, meaning you're insulin resistant, you're going to want to deal with that. There are a number of prescription treatments to deal with that. Nowadays, people are very excited about all the GLP1 agonist, but in addition to that, regular cardiovascular exercise and resistance exercise, making sure that your body fat percentage

is not in excess of where it needs to be. And everyone has a slightly different idea of where it needs to be, both cosmetically and for health. So that's a conversation between you and your doctor and you and you, frankly. But you want to avoid being insulin resistant because being insulin resistant and being obese can indeed lead to hair loss.

And there are many people out there who are not obese, who nonetheless are experiencing hair thinning and hair loss because they are insulin resistant by way of reduced IGF1 activity. There are a few supplements, so these are over-the-counter supplements, such as myo and acetal, taking it dosages of about 900 milligrams before sleep, which by the way can also assist

in sleep, or things like burbering or metformin, which are known to improve insulin sensitivity. Each and every one of these has its own profile of positive and negative effects. The lowest number of side effects is associated with 900 milligram myo and acetal, taken about 30 minutes before sleep, most because it can make people a little bit drowsy, and it does aid sleep in some really great ways. But really exercise and maintaining a healthy nutritional program are also going to be key. You just can't discard those. Burberry, which is a substance made from tree bark, is sometimes called the poor man's metformin, metformin being the equally effective prescription version of burberry, or put differently, burberry is the non-prescription, but equally effective version of metformin.

Keep in mind that both burberry and metformin dramatically reduce blood sugar levels, and so if you're not going to take them with carbohydrates, it can lead to some feelings of discomfort. That's why I'm not a fan of them, but if your goal is to really improve insulin sensitivity, they are considered very potent tools on the list of things that can do that. The other thing that's really important for maintaining proper hair growth, this antigen phase, is that you need sufficient iron. This is because iron and ferritin play a key role in the cell growth pathways that go from the stem cells to the stimulation

of keratin within the hair itself. Don't have time to go into this pathway in a lot of detail, but you can have your blood levels of iron measured. This turns out to be pretty important because you don't just wanna start popping iron supplements because too much iron can be toxic, too little, means you're anemic. For women, the levels of iron that you want are somewhere between 25 and 100

and for men, somewhere between 30 and 150. Fortunately, the tests or the blood tests for iron are usually a very inexpensive ad to your current blood panel. So if you're going in for a blood panel for LDL, HDL, typical things, or if you're doing the more elaborate hormone testing, which I do recommend people do if they can afford it, or if their insurance covers it, do ask for an iron test as well, and if your iron is low, you may need to supplement your iron. If your iron is too high, that's not good either, but iron plays a key role in the antigen phase of hair growth. So you want to make sure you at least have sufficient iron, and if you don't, you want to make sure that you're getting it from nutrition and or supplementation. Okay, so earlier, we were talking about dihydrotestosterone.

Dihydrotestosterone, just to jog your memory, is a form of testosterone that combine the Androgen receptor at five times the affinity of regular testosterone. Both men and women have a lot of testosterone relative to estrogen. Just so happens that men tend to have more testosterone than women do overall. But both men and women, as they age, convert more of the testosterone they have to die hydro testosterone. And die hydro testosterone does two things that are bad for hair maintenance and hair growth. First of all, it shortens the antigen phase, that growth phase.

So whatever hair is going to grow is going to occur over a shorter period of time. Second of all, because of the presence of angrogen receptors on the stem cell niche area and around it, it actually miniaturizes the follicle and the stem cell niche. In other words, it makes the population of cells that give rise to more hair protein, smaller, and can eliminate it all together. And that is why anything that reduces 5-alpha reductase is going to reduce DHT, is going to maintain or extend the growth phase, the antigen phase of hair growth, and is going to offset or prevent some of the tillagen phase, the pinching off and the removal of that

stem cell niche. Now, one substance that we know can inhibit five-out for a ductase, although it does it pretty weekly, is Saul Palmetto, which is an extract of the Saul Palmetto berry. To be honest, I don't know how this was initially discovered. If anyone knows, please put it in the show note captions. When I looked online, I found a bunch of conflicting stories about who was the first person to start extracting

the extract of the Saul palmetto berries. So I have no idea which one of those is true. Maybe somebody can tell me. The good thing about salt palmetto treatment is that it is known to have very few if any side effects. There might be some side effects in about one percent of people, but it's not associated with a lot of side effects. It's also known that when taken at about 300 milligrams per day, and here

it doesn't have to be that strict. Most of the studies that I explored involved taking anywhere from 200 to 500 milligrams of salt palmetto, but most of them focused on about 300 milligrams of salt palmetto per day, divided into two or three doses. Why? Well, it has a relatively short half life, meaning it's going to get cleared from the bloodstream and more importantly, its biological action is going to be very short-lived. So if you can get a hold of 50 or 100 milligram capsules or tablets of salt palmetto and divide those up, take them in the morning after noon and evening or even just in the morning and evening to achieve a total of about 300 milligrams per day, that's going to very likely help you hold on to some of the hair that you would

have otherwise lost, maybe even grow some new hair. And I say maybe give you some new hair growth because sulpomato is not known to be a particularly robust treatment for the reversal of hair loss. It's known to have some effect, but it's generally taken in conjunction with a bunch of other things. And so it's really hard to tease out just what amount of hair growth or prevention of hair loss is due to salpometer specifically. But I mention it here because the mechanism of action is logical and fairly well known, which is this weak effect in reducing five

alpha reductase in there by reducing DHT. So again, because it has relatively low side effects, even though it's not super effective and because it's fairly low cost and it's available over the counter, I felt it was important to include. Now as soon as people hear things like salt palmato berry, they're probably also thinking, oh boy, here you come all the herbals. Now keep in mind that there are some herbal compounds that have pretty robust biological effects. compounds that have pretty robust biological effects. Talk before in our optimizing testosterone episodes about things like Tonga Ali and Fidoji Agrestis, which take in the correct dosages and in the correct way, can be pretty potent for increasing luteinizing hormone and free testosterone.

Not going to have huge effects. It's not like taking exogenous, anabolic steroids, but they can have real effects. So herbal compounds can be potent. However, I do acknowledge that there's a vast market out there of herbal compounds and plant-based compounds that people are arguing, mostly the people who sell them are arguing, can increase hair growth. And there are some decent studies of these things. The hard part about studying these herbal compounds

and these plant-derived compounds for increasing hair growth is that they are often taken in combination with one another. In fact, most of the hair growth supplements that involve these herbal compounds and plant compounds include five or ten, sometimes even more things altogether. So teasing out which ones are effective and which dosages are effective is merely impossible. There are just too many variables. So you will hear, for instance, that green tea extract, racie mushroom, pumpkin oil, zinc, curcumin, that all of these things can increase hair growth. Perhaps the only thing on that list that makes logical sense with respect to the biochemistry is that curcumin is known to, in some people, be a potent inhibitor, a

five-alverer ductase and DHG, so much so that I can personally say for me, I once took Curcumin turmeric, it's also called in high dosage, this is about a gram to two gram capsules and I felt absolutely terrible. I mean, just dreadful. I don't care if it allowed me to keep my hair forever. I would rather lose all my hair three times over,

well, I guess that means it would have grown back. I'd rather lose all my hair three times over, well, I guess that means it would have grown back. I'd rather lose all my hair. Let's just put it that way. Then ever take curcumin or turmeric and high dosages again. And in saying that, I know that many people take turmeric and curcumin and really like its anti-inflammatory properties and don't experience any side effects. I just happen to be particularly sensitive to curcumin by way of this DHT pathway. And I know this by way of blood work.

So I'm never going near that stuff again. That said, a lot of these herbal compounds and cocktails probably will have some minor marginal infinitesimally small, somewhere in that range, a fact on maintaining hair growth or in stimulating new hair growth. It's just that there really aren't clinical studies to support any one of them. And that's why I singled out salt pometo is one of the few for which the biochemical pathway of inhibiting file file for reductase

and the low incidence of side effects and the fact that many people have used it with some degree of success makes it a standalone, I wouldn't say recommendation, but a consideration. Another commonly discussed and used commercial compound for offsetting hair loss and stimulating hair growth is keto-conazole. Sometimes this is known as Nisarol, where Nisarol is the brand name of a shampoo. Keto-conazole is an anti-fungal that was initially developed to treat dandruff and severe psoriasis. So, keto-conazole has been shown to be

effective in increasing hair number. It's has been shown to be effective in increasing hair number. It's also been shown to be effective in increasing hair diameter, which is somewhat surprising because one of the common side effects of ketoconazole is drying, shitting, and brittle hair. So what's going on there is a little unclear we'll return to that in a moment. The mechanism of action for ketoconazole is pretty interesting.

Remember earlier we were talking about the sebaceous gland and the production of sebum, that oily stuff, whose very name seems to evoke disgust in certain people. Well, keto connozzles can disrupt some of the fungal growth that frankly we all have on our scalp all the time. I know this is a surprise to many of you, but you are constantly bombarded with viruses, bacteria, and funguses all the time.

But we manage to battle those off with our immune system either by physical barriers such as an oil barrier, like the sebum, or through antimicrobial action, so chemical approaches, our immune system, the sebum, etc. Ketoconazole acts as an anti-fungal that in some way seems to reinforce the properties of sebum at keeping out other fungal infections. And the net effect, at least as far as we know, is a mild reduction in DHT. Now, exactly how this happens isn't really clear.

What is clear is that the use of ketoconazole shampoos, two to four times per week, with a scalp contact time of about three to 5 minutes, has been shown to give about an 80% response rate of maintaining hair that would otherwise be lost. So that's pretty dramatic, 80%. What is less clear is whether or not ketoconazole shampoo can actually stimulate new hair growth. But as you're probably starting to realize, this is always a bit of a tough thing to disentangle maintenance of hair that you would have lost versus new hair growth. Certainly that's an easy thing to disambiguate if you have a patch of scalp where there

is absolutely no hair. These so-called dead zones that you can resurrect with certain treatments. But what about areas of your scalp where hair is thinning? So for instance, on the top of your your head this is where many women will first experience pattern hair loss alopecia is right at their midline. You know if especially if they have a part right there they'll start to notice that under very bright light for us in light in particular they'll notice that thinning of their hair there or in the forehead region. They'll start using ketoconazole shampoo. Again the typical recommendation is two to four times per week with a scalp contact time of three to five minutes and really rubbing it in and then using ketoconazole shampoo. Again, the typical recommendation is two to four times per week

with a contact time of three to five minutes and really rubbing it in and then rinsing it out. You don't need to be super vigorous, but you want to make sure that it gets down into the follicle and around the follicles, not just sitting on top of the hair, which is going to be especially important for people who have long hair to really massage it in. Well, they will experience a growth of hair in that particular region that almost certainly were due to miniaturization of the hair follicle and reduction of the total population of stem cells in that follicle as opposed to complete loss

of the stem cell population. The reason we say this is that there's no reason to think that ketoconazole can actually stimulate IGF1 or activate growth itself. It's probably offsetting some of the reductions in the antigen phase and some of the exacerbation of the tillagen phase. Now if you decide to use ketoconazole as an approach to offsetting hair loss, it's very important that you get a hold of a shampoo that's at least 2% concentration of ketoconazole.

This is important because a lot of the ones that are available out there, especially online, are going to be 1% or lower. So you want to try and obtain a ketoconazole shampoo of 2% or higher concentration of ketoconazole, because it has other things in it, of course. I should mention that there are occasional side effects with ketoconazole, the rates of side effects from the meta-analysis and reviews that I read,

where somewhere between 1 and 8% of people will experience some side effects. But those side effects tend to be pretty mild. Things like irritation of the scalp, things like thinning and brittleness of the hair that sometimes can be offset by using shampoos that contain things like biotin. I know many people are probably curious about biotin, which is a protein that can be incorporated into the keratin. Whether or not different biotin and rich shampoos can really enhance the

total amount of biotin that gets incorporated into the hair isn't clear, but it is clear that having sufficient biotin around is important. So if you get a little bit extra from your shampoo, you can imagine how that would, quote, unquote, tap off the amount of biotin in that hair. And there are people out there saying that biotin and rich shampoos have done wonders for them, who knows? I'm not going to dispute their experience. So if you're going to use ketoconazole, keep in mind that the more typical brand names that are out there,

you know which ones they are, oftentimes don't have 2% or if they do have 2% they can be very drawing and lead to brittle hair. There are newer and now fortunately a greater variety of ketoconazole containing shampoos. We as a podcast and I don't have any affiliation to any of these, but I will provide a links to a couple of the more prominent ones that are known to have 2% concentration of ketoconazole as well as some other things in them known to offset some of that dryness and brittleness that ketoconazole shampoos can trigger. So by now I think it will be

abundantly clear why inhibiting five alpha reductase and thereby reducing DHT should increase hair growth because of the negative impact that DHT has on the hair follicle. The major player in this whole story around inhibiting five alpha reductase and reducing DHT to maintain or increase hair growth is going to be finasteride and its close cousin do test ride. Finasteride is effective in reducing DHT because of its actions in reducing the type 2 isoenzyme or isoform of five alpha reductase. It turns out there's three different isoforms or what are sometimes called isoenzymes of five alpha reductase.

This is getting pretty far down in the weeds. What I think most of you just need to know is that finasteride reduces DHT. That's the net product of finasteride. And in doing so, it can increase hair count by as much as 20% pretty remarkable, if you think about it. In addition, finasteride treatment done properly, which we'll define in a moment, can reduce hair loss in 90% of all people that take it. That is near staggering. There aren't

many pharmaceuticals out there that have that kind of efficacy, really dramatic. And in addition, it's known to increase hair thickness by about 20 to 30% overall. So not just create new growth of hairs and thicker hairs, but whatever hair you do happen to have on your head, it can further thicken those. So the finasteride story is one, I think, of general success. I mean, it really seems to improve hair growth and help you hold on to the hair that you have. The issue with finasteride is twofold. First of all, it is known to have some pretty significant side effects if it's not dosed properly and in particular populations of people.

This is because there is a wide variation in the amount of the different isoenzymes that people make. This is why I brought up the isoenzymes earlier. Some people make more of isoenzymes that people make. Yes, this is why I brought up the isoenzymes earlier. Some people make more of isoenzyme one and three. Some people make more of isoenzyme two and three. And every variation thereof. So when people take finasteride, some people are very strong responders

and they achieve really effective hair regrowth and maintenance of hair. Other people less effective, although still pretty impressive, but the catalog of side effects that people experience at a given dose varies widely. So there's a lot of trial and error that has to take place. Also should point out that finasteride comes in two major forms. There's an oral form and there's a topical form.

So this is not unlike our discussion of monocidil earlier. Topical finasteride is typically taken in 1% solution or ointment and rubbed into the head. Sometimes it's now also incorporated into shampoos, but typically it's put into a solution that people rub into their head. And it is thought that the 1% solutions are equivalent to 1 milligram of systemic finasteride.

Now we need to take a step back and ask, why was finasteride developed in the first place? Well, finasteride as a fairly potent 5-alpha reductase inhibitor, it's great at lowering DHT. It was developed for treatment of prostate enlargement and various issues of the prostate that are associated with L of A DHT that occurs with A. The topical finasterides were designed with the hope that the fanasteride would make it into the hair follicle and would inhibit DHT there and allow for more growth of the hair, which apparently it does, but not make it into the systemic circulation

or at least not at concentration sufficient enough to cause as many side effects as with the oral dosing. Now the problem is it does make it into systemic circulation. The issue is also that topical application of finasteride is harder to dose than oral finasteride. I'm not saying you should be taking oral rather than topical finasteride, but keep in mind that the dosages of finasteride that have been shown to be effective for inducing hair growth cover an enormous range.

So as low as 0.01 milligrams per day and as high as 5 milligrams per day, which is a just staggering range. Now, when trying to simplify the problem of how much finasteride to take, either by way of oral tablet or by way of topical solution, we can get a bit of leverage on this by thinking about how much DHT reduction occurs as a function of dose. And there, finasteride shows this really interesting what's called logarithmic distribution. What it means is that for a dosage of 0.01 milligrams of finasteride, you're going to achieve approximately 50% reduction in DHT. And that's systemic DHT. So this is a blood draw measuring your DHT, then taking 0.01 milligrams of finasteride, again, 0.01, very low dose of finasteride. I'll appear to a couple weeks, measure people's DHT in their blood again, and you see that it's reduced by 50%. However,

at increasing dosages of 0.2 milligrams, 1 milligrams, 5 milligrams of oral, finasteride per day over the same period of time. The increase, or I should say, the reduction in dihydrotestosterone doesn't increase linearly. It's not that you go from 50% to 60% to 75% to 100% with each increasing dose. It tapers off. It kind of flattens out. It tends to increase a little bit, but it's sort of a gradual slope increasing as you head from .2 milligrams out to 5 milligrams. So what this means is that given that reducing DHT can cause very side effects, sexual side

effects, reductions in either sexual function or sexual drive, as well as overall drive and motivation, sometimes even some impressive symptoms, that everything points to taking the lowest effective dose of finasteride and starting with a very low dose of finasteride, because low doses of finasteride, even at that point, 0.01 milligrams taken orally daily are already leading to a 50% reduction in dihydrotestosterone and thereby, taken for a long enough period of time, should offset hair loss and stimulate hair growth. One of the problems, however, is that people will start taking finasteride at a low dose, you know, 0.1 milligrams or 0.2 milligrams, maybe even 0.01 milligrams.

And there will be a reduction in their DHT, but because of the long duration of that antigen phase, they don't see a lot of change in hair growth in the first month or even two months. And so what they end up doing is increasing their dosage and then they start to see hair growth, but then they start to experience more side effects. Now the side effects of oral finasteride are serious enough and Common enough in people that take finasteride that the topical solutions were developed But there are two one needs to exercise caution because if we are going to translate between topical finasteride and Oral finasteride with the understanding that topical finasteride can actually make it into the systemic circulation We need to look at what's been shown in clinical studies

Which is that for for instance, taking one milliliter of .25% phenastride applied to the scalp. This is a very typical recommendation. Translates to the same thing that would be achieved with 2.5 milligrams of oral phenastride. And when I say translates to the same thing, what I mean is it leads to the same concentrations in the blood. Now consider that 0.2 milligrams, 0.2 milligrams of finasteride in the blood is known to be effective in generating new hair growth and maintaining hair that one already has when

they start the treatment. So if you think that the topical finasterides are actually creating lower overall systemic concentrations of finasteride that is not necessarily the case. Again, 1 milliliter of topical finasteride at 0.25% leads to a 2.5 milligram concentration in the blood. When the effective dose within the blood stream by taking it orally as a pill is 0.2 milligrams, that might not seem like a big deal to you, although it is a big deal, right? We're trying 2.5 milligrams versus 0.2,

but it is a huge deal when you consider that the side effects of finasteride increase as you increase the concentration of finasteride in the bloodstream. So where does this leave us? Should people who are interested in taking finasteride take the oral form at low dose or take the topical form and simply try and apply it less often or guess at what their systemic concentration of finasteride is? Well, it's going to vary from person to person. Some people are very sensitive to finasteride

and not in the good sense. The side effects just really show up quickly and they tend to be dramatic. Other people, not so much. The dosage recommendations that I was able to arrive at based on the clinical studies and frankly in discussion with some doctors who prescribed finasteride were the following. .5 milligrams to 1 milligram of finasteride as a tablet per day seems to be an effective and pretty safe starting place for most people. Now some people will find that even that 0.5 milligram dosage is just going to

cause side effects that are not going to work for them and they're going to either have to reduce their dosage if an asteroid or move to the topical or maybe cease taking an asteroid altogether. But for many people out there that's going to be pretty well tolerated. The key thing here is that one is going to have to wait some period of time to see whether not any hair growth occurs. It is a naive and frankly foolish approach based on what we know about the duration of that antigen phase of the hair to do one of these treatments way to week or two and then decide to up your dose. Now, it is not foolish to reduce your dose if you're experiencing bad side effects, but to simply increase your dose because you, it is not foolish to reduce your dose if you're experiencing bad side effects,

but to simply increase your dose because you're not getting results quickly enough, that's not going to be the best approach. I really encourage people who are going to explore the finasteride route to think of this as a long-term project and to really ratchet up slowly, if at all, starting initially with a low dose taken for a long period of time, maybe even as long as 25 weeks before considering going up any further. Certainly, as I mentioned before, if you need to go down further, that's not going to be a problem, at least not in terms of reducing side effects. I mean, you're not going to get additional hair growth, but you're certainly not going to increase your side effects if you reduce your dose. However,

I will talk a little bit later about post-fenasturide syndrome, which is something that's getting increasing attention nowadays. That's something that occurs after people have taken fenasturide for an extended period of time. Now, some of you have perhaps heard, and I'll just tell you right here, that the topical forms of fenasturide are associated with far less side effects. Now that might come as surprising, given that topical application of fenasturide can lead to systemic distribution of fenasturide. But the numbers that are out there right now are that topical finasteride is associated

with 30 to 50% fewer side effects or 30 to 50% less severe side effects than oral finasteride. Now, there are several things probably responsible for that. One is that people tend to ratchet up their dose of oral finasteride pretty quickly. But keep in mind that the effective dose of finasteride in the blood is 0.2 milligrams. Earlier, I said the typical topical finasteride solutions are 0.25%. People are taking one millivit that equates to 2.5 milligrams and so it seems like a massive overdosing. Ah, but here's the discrepancy and here's where we can arrive at some reasonable recommendations.

If you decide that finasteride is write for you, you get a prescription. I would hope that you're monitoring your DHT levels and other hormone levels. That would be ideal. And working with a doctor, please. 0.5 milligrams to 1 milligram per day of oral finasteride seems to be the best starting place. For topical finasteride, it's going to be that 1 milliliter, a point to 5% that we talked about earlier, but that's taken only one time per week. And you can fully expect that right after the

application, you will have higher levels of finasteride in your bloodstream, and therefore lower levels of DHT, and that that will alter across the week. Most people are not going to be able to measure their DHT on a day by day or even weekly basis. It's just too expensive and labor intensive. But I think those dosing regimens ought to get people into more or less the same category of optimizing hair maintenance and hair growth

while minimizing finasteride side effects. One point about finasteride taken either alone or in combination is that in recent years, really in the last five or so years, there's been increasing discussion about so-called post-finasteride syndrome. Now post-finasteride syndrome is indeed a new phenomenon in the sense that finasteride has been prescribed for a very long period of time for treatment of the prostate at dosages of about 5 milligrams per day. That's a very high dose. Sometimes lower, but as high as 5 milligrams per day. For many years, there was no discussion about this post-fenasturide syndrome. What is post-fenasturide syndrome?

Post-fenasturide syndrome is when, typically, it's males, this is where it's been described, will take finasturide at any range of dosages from 1 milligram to 5 milligrams per day. They're either doing this for prostate or more likely they're doing it to offset hair loss and increase hair growth. And then they stopped taking finasteride for whatever reason, financial or it wasn't working for them or the side effects were not to their liking. And they start to experience some very severe what can only be called syndrome effects such as very reduced libido, very

reduced erectile function, very reduced mood to the point of depression, even suicidal depression. So this is pretty scary stuff, especially since it's occurring at an age when most of these things are not typically occurring in males, they can occur, but they're not typical of younger males in their 20s and 30s and early 40s. We have to ask ourselves, what's going on here? After all, people have taken finasteride for the prostate at fairly high dosages without this post-finasteride syndrome when they've stopped.

Now these young males are taking finasteride, they're coming off finasteride and they're getting this very severe, very debilitating post-finasteride syndrome. This has become a kind of hot topic, enough so that medical doctors who have been prescribing finasteride for a very long time have been forced to address this. I think at first they were sort of perplexed and thought, I don't know, this might be psychosomatic, whatever that means. I mean, as a neuroscientist who works on mind-body connection, we know that nothing is truly psychosomatic. Everything is of the mind and body. But the point is that enough medical attention has been placed on post-fenasturized syndrome and trying to unravel exactly what that is, where there are now a few general conclusions

about what might be going on. First of all, it seems that younger males taking fenastride, in particular, high dosages to improve hair growth or offset hair loss, seems to be one of the key variables. We're not seeing this post-finasteride syndrome as much in older males. In fact, it seems to occur more in males in their 20s and 30s than males in their 40s and older. So that's one thing that may relate to the ways in which dihydrotestosterone, we know, has a very key role in early embryonic development. It's actually what's responsible for the male genitalia.

It's also responsible for certain things in female development, but mainly in utero, it's responsible for male development and development, the penis in particular. And then around the time of puberty, dihydrotestosterone acts again in what's called its activating effects to further increase growth of genitalia, increase the musculature, bone growth, etc. and increase libido and a number of other things. It's probably also involved in the activation of puberty. It's certainly not the only hormone involved in the activation of male puberty, but it's certainly one of the key players.

So dihydrotestosterone has these known early roles in embryonic development and impuberty. But what post-fenasturied syndrome seems to indicate is that dihydrotestosterone is likely having further effects on male maturation, in particular maturation of the hypothalamus and areas of the brain that continue well into one's 20s and maybe even one's 30s. And here I just want everyone to keep in mind

that we tend to think about development as childhood teenage years, young adulthood adulthood, but really development never stops. Development is something that starts at conception and birth of course, and then extends all the way out until the point when we die. So even if we live to be in our late 90s or achieve a hundred years of age,

development is occurring that entire time. And these different hormones, such as dihydrate testosterone when we die. So even if we live to be in our late 90s or achieve 100 years of age, development is occurring that entire time. And these different hormones, such as dihydrotestosterone, are having different impact for across the lifespan and in different ways across the lifespan. So there isn't a clear conclusion about what post-fenasturide syndrome is really all about, but it points to the fact that DHT is likely to be involved in development of the brain and the brain to genital axis, because I mentioned that because so many of the side effects that are associated with this post-fenasterized syndrome seem to center on sexual side effects, although they're also the depressive side effects.

Of course, those can be related to one another in either direction. So while I do understand that loss of one's hair or potential loss of one's hair can be particularly troubling and anxiety-provoking, even caused depression, in some cases, I am While I do understand that loss of one's hair or potential loss of one's hair can be particularly troubling and anxiety-provoking, even caused depression in some cases, I am sensitive to that. You also want to be sensitive to the fact that some of these treatments, such as finasteride, can carry very serious side effects even if you come off them, aka post-finasteride syndrome. As long as we're talking about finasteride and this general pathway of 5-alpha reductase inhibition and thereby DHE-A inhibition and on and on topics

and themes and nomenclature you are now very familiar with. We have to talk about due tasteride. Due tasteride is yet another molecule similar to finasteride but remember those three isoforms of the five alpha reductase enzyme? Well it inhibits all three mainly type one and type two, but also type three. And it does it very potently. So as a consequence, the typical dosage of oral dutastride, get this, 0.5 milligrams to 2.5 milligrams taken orally, works two to five times faster than typical finasteride at inducing hair regrowth and reduces DHT by get this 95%.

So it's just near flatlines DHT. And that can occur at concentrations as low as 0.5 milligrams, although you will see prescriptions and people taking due to astride anywhere from 0.5 milligrams all the way to 2.5 milligrams orally. Now not surprisingly, due test ride is associated with a lot of side effects related to the DHT pathway. So things like reduction in sex drive, reduction in overall drive.

It also tends to impact other hormone pathways, so increases in estrogen, prolactin. That's why gynecumastia, growth of male breast tissue sometimes occurs when people take due toastride. And so you're probably asking, why would anyone take due toastride? Why not just take finastride and wait for that hair growth? Well, the answer is that people are often very impatient and it turns out that due toastride works about two to five times faster than finastride. So some people don't want to wait a full 30 weeks

or 40 weeks or 50 weeks or more in order to grow their hair back. And they're very concerned about the hair loss that's occurring. So they will take what I hope would be a very low dose of due-tastride. I realize that there are ways to take due-tastride that can be safer, offset some of these side effects.

But by my read of the literature, if one is going to try to mildly inhibit the DHT pathway, things like salt, palmetto, things like topical caffeine, which has some effect on the endogen pathway, but as we talked about earlier, tickles other pathways, things like ketoconazole, mild reduction in endogen receptor pathways in the follicle, and very direct because it's supplied directly to the scalp. Things like that are going to be the best route for mild reductions in DHT as an attempt to maintain hair or grow hair, whereas if one really wants a potent stimulus for increasing hair growth,

that's very likely going to be finasteride, and hopefully low enough dosages of finasteride, and hopefully a patient enough patient person that they are willing to wait the duration of time required for that hair growth to come back because they understand that that energy and phase take some time. Now the holy grail of all this hair stuff is in understanding that no one specific treatment is magic. And in fact, there are now a number of good meta analyses comparing the various treatments

we've talked about today, alone or in combination. We can summarize that pretty easily by saying that combination treatments that involve a mechanical stimulus and a chemical stimulus are always going to be better than either one alone. Within the mechanical category, the stimulus that seems to work best is microneedling. The combination of microneedling and finasteride can lead to some pretty robust and impressive hair regrowth, so much so that people that were, I guess we don't need to describe them as pretty bald

or bald, can regrow significant amounts of hair. I've never seen examples of people who were completely bald, meaning lacking all scalp hair to grow back a full head of hair. But the combination of microneedling and finasteride is probably the most effective way to go. And if you're going to do that, there's no reason why you couldn't also use ketoconazole shampoo, couldn't also use salt, palm meadow. There's no reason to think that these things collide with one another, although anytime you're inhibiting a DHT pathway,

or whether or not you're increasing or decreasing any hormone pathway for that matter, you want to be careful about layering in too many different treatments because you don't want your DHT level to go too low. I mean, let's keep in mind that even if you take a very low dose of finasteride and reduce your DHT and don't have side effects, maybe just the mere addition of salt palmetto, which leads to a slight reduction in DHT, combined with some caffeine ointment, would be sufficient enough to start inducing some of the low DHT associated side effects. So you really have to see for you. And that's one of the major issues in this whole field of hair growth and regrowth is that people are highly individual in their response and in their side effect profile to these

various treatments. But there's an enormous range there and unfortunately there's no way to know a priori before doing these treatments, what your response is going to be in terms of side effects. So you're simply going to have to explore, and I would hope that you would explore starting with minimal possible effective dosages and to do that in coordination with a medical professional. So you could really evaluate these things at the level of blood and cosmetic changes. And in fact, that's a pretty good motivator for thinking about the different treatments

that we talked about today. Everything from mechanical treatments, as simple as massage, which we've all heard about, but for which there really aren't a lot of data for supporting hair growth, but certainly things like microneedling, which is a mechanical stimulus for which there are pretty good data that it can improve hair growth. Also things like salt palmetto, a weak DHT antagonist. Also things like ketoconosol shampoo, which again is a weak DHT antagonist and operates through some other pathways as well to stimulate hair growth. My suggestion is that anyone, young, old, male, female who's thinking about embarking on various treatments for offsetting hair

loss and stimulating hair growth, consider both mechanical approaches and the approaches that attack the chemical pathways that can stimulate hair growth and can inhibit the inhibitors of hair growth. In fact, that's the reason why we spend so much time on the biology of hair growth and what shuts down hair growth early on in today's episode. And then systematically went through each of the various treatments that relies on,

and in some cases hinges entirely on either a mechanical stimulus or a chemical stimulus in order to exert its effects. My goal today was not to overwhelm you with a ton of biology about hair, although we did cover a lot of biology of hair and stem cells and hair growth. My goal in describing all that was really for you to be able to hear about various treatments, whether or not it's lasers or PRP or finasteride, do task-dried, or whatever is coming next that we're sure to hear about soon online and from the medical community. And to be able to place those into bins related to their known or potential mechanisms. And then to be able to step back and evaluate which, if any of those treatments might be right for you. If you're learning from and or enjoying this podcast,

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