The Dr. Hyman Show - What If We Got Sunlight All Wrong? The Truth About Vitamin D & Chronic Disease

Episode Date: July 14, 2025

Sunlight has long been vilified for its link to skin cancer, yet hiding from it entirely may be costing us far more. Vitamin D, made primarily through sun exposure, plays a pivotal role in everything from bone strength and immune defense to mood regulation, cancer prevention, and even longevity. Shockingly, over 80% of people have levels too low to unlock its protective powers—putting them at greater risk for chronic illness, and even premature death. Research shows that raising vitamin D to optimal levels could prevent hundreds of thousands of deaths each year, rivaling or surpassing the impact of many medical interventions. With a few minutes of daily sun, the right kind of supplementation, and awareness of how our lifestyles block this essential nutrient, reclaiming our health may be simpler than we think. In this episode, I discuss, along with Dr. Cindy Geyer, the critical role of vitamin D in preventing chronic disease, boosting immunity, and promoting overall health. Dr. Cindy Geyer received her bachelor of science and her doctor of medicine degrees, with honors, from the Ohio State University. She completed residency in internal medicine at Strong Memorial Hospital in Rochester, N.Y. and is triple board certified in internal medicine, integrative medicine and lifestyle medicine. This episode is brought to you by BIOptimizers. Head to bioptimizers.com/hyman and use code HYMAN10 to save 10%. Full-length episodes can be found here: Do You Need To Take Vitamin D?Choosing Skin Care Products that Won’t Make You SickWhy Boosting Your Vitamin D Could Change Your Life

Coming up on this episode of the Dr. Hyman show, you really could make a dramatic difference by just getting people's levels of vitamin D up to 45 nanograms per milliliter and that would literally lead to 400,000 fewer premature deaths a year. That is no joke. You don't need more caffeine or another stress supplement. You might just need more magnesium. Magnesium supports sleep, mood, energy, and focus, but most of us are missing it. That's why I recommend magnesium breakthrough by bioptimizers. It combines seven forms of magnesium

for results you can feel in your mood, sleep, focus, and more. Try it now for 10% at bioptimizers.com slash Hymen. Your body will feel the difference. Before we jump into today's episode, I wanna share a few ways you can go deeper on your health journey. While I wish I could work with everyone one-on-one,

there just isn't enough time in the day, so I've built several tools to help you take control of your health. If you're looking for guidance, education, and community, check out my private membership, the Hymen Hive, for live Q&As, exclusive content, and direct connection. For real-time lab testing and personalized insights into your biology, visit Function Health. You can also explore my curated, doctor-trusted supplements and health products at DrHyman.com. And if you prefer you do it right, you don't overdo it. But you kind of need the sun for many reasons, because of our hormonal systems, our circadian rhythms, vitamin D, which is critical for our health.

And I do get why people are a little worried about sun exposure. I mean, according to the Environmental Working Group, or EWG, more than two million Americans get skin cancer every year, and half of those who live to 65 get at least once. Now these skin cancers that are basal cell and squamous cells are not fatal, they don't spread. There can be disfiguring. My grandmother had a big one on her scalp, which was terrible, she never wanted to get it treated,

and it was kind of nasty. But basically the squamous and basal cell cancers that you get on your skin are linked to sun exposure. Melanoma, not so much, and that can occur in non-sun exposed areas and be a little bit of a different animal. Now, the other thing about sun exposure is particularly on your face.

It's going to cause something called oxidative stress, and that leads to inflammation. Oxidation is kind of like your car rusting or an apple turning brown in the air but it's really the same thing that happens on your skin. You get wrinkles. So the wrinkling is from the oxidative stress from the sun. You see people who have been in the sun a long time, they get kind of wrinkly leathery skin and ladies who wear parasols have this beautiful porcelain skin as they get older.

So your face is something you definitely want to protect. But also we're supposed to be out in the sun and so staying out of the sun or overlying on some block actually can cause issues because vitamin D is critical for mood, for energy, for thyroid function, for cancer protection, for immune function, preventing infections, even COVID. And it's a problem if you don't get enough vitamin D. And the problem is most of us don't get vitamin D because we don't live out and work outside anymore.

Most of us are inside most of the time. And we get deficient in this really important vitamin called vitamin D. And the truth is that probably 80% of Americans are deficient or have insufficient levels of vitamin D, levels that don't protect them optimally from the things that you want to have vitamin D protect you from, whether it's osteoporosis or depression or cancer or to boost your immune system so you don't get things like the flu or COVID. I mean, if you have a high vitamin D levels, your reduction in flu is 75%. or cancer or to boost your immune system so you don't get things like the flu or COVID.

If you have a high vitamin D levels, your reduction in flu is 75%. That's more than the flu vaccine. So it really is a powerful nutrient. It's very safe at the recommended doses. It's easy to take. There's no side effects. It's very cheap. And it's such an incredibly important vitamin for optimizing your health in every way, including longevity. So, let's talk about vitamin D a little bit. Now, people think they should be avoiding the sun to not get skin cancer, but vitamin D actually protects you against skin cancer, believe it or not, and reduces the risk of melanoma dramatically and many other cancers, not just skin cancer.

It actually reduces overall mortality by 7%. So just having good vitamin D levels reduced the risk of death by 7%. And vitamin D, we used to get from sun, running around naked hunting and gathering, and also if we were living in colder climates, we would eat fish, wild fish like herring and sardines and mackerel. These fatty

small fish have pretty high levels of vitamin D. Also mushrooms, so if you're foraging and going for mushrooms, there's a lot of like porcini mushrooms have the highest levels of vitamin D, but it's still hard to get enough in you. We're not getting these foods anymore. So, you know, we saw such an, with the industrial revolution, this incredible advent of rickets and vitamin D deficiency and it's one of the major areas where we've seen a public health improvement by getting awareness of vitamin D. Then it's been fortified in milk. Milk doesn't necessarily have vitamin D. It actually doesn't have vitamin D. It only

has vitamin D because it's added in to the milk. So if you think you need vitamin D to get your, I mean milk to get your vitamin D, that's not actually true. You don't get a vitamin D from milk only because it's added. Now, most of the problem with vitamin D is that doctors don't understand how to diagnose it. They might even order the wrong test.

They don't know the right treatment. They don't know the doses. They don't understand its importance. And they see the reference levels on lab tests, which are typically like 20 nanograms per deciliter. Now that is ridiculously low and I think if you look at what's optimal, it should be over 45 or 50. And so many, many people are in this sort of borderline area of less than 20 or 20 to 50 where they do need more vitamin D. Now most doctors think,

oh, you don't have rickets, you don't have vitamin deficiency or your number is like 20 or 30, you're fine. And they're actually wrong. And the question is, what's the dose you need to not get rickets? It's probably like 30 units a day. It's not what we need for optimal health. What we need for optimal health might be more like 5,000 units a day. I mean, even the government's upper limit is 4,000 or 5,000 a day as a safe dose. You're not going to get into trouble with that. Some people are very good at absorbing it, others aren't. Some people need actually up to 10,000 units a day. It was one study where they gave healthy young adults 10,000 units of vitamin

A for three months and there was no toxicity from that. Now you can get toxicity if you take a lot more. I mean, and it can cause a problem, but it's far lower than we think. In fact, your level has to be over 250. Even though the reference range on the labs is up to 100, it doesn't really become toxic until about 250. So the real question is how much should we be taking on a daily basis? And I think they're depending on you and your vitamin D level, your sun exposure.

I mean, I have a friend who lives on the beach and goes out surfing every day and his vitamin D level is about 45, which is pretty good with no vitamin D supplementation, but I rarely see that unless she's living in Mexico on the beach all the time. But if you aren't, you probably need between two to 5,000 units a day of vitamin D.

What's really concerning is when you look at the data, it's 80% of us who are insufficient or deficient. This is either frankly deficient, let's say less than 30, which is now the reference range on most labs, although some still say 20, and those who are between 20 and 50. So I think that's important because vitamin D deficiency is linked to many cancers, high blood pressure, heart disease, diabetes, depression. We call it seasonal affective disorder or SAD, fibromyalgia.

I mean, you know, people have muscle aches and pains. These are often from low vitamin D levels. Bone loss, obviously osteoporosis, even autoimmune diseases and multiple sclerosis is found in much higher levels in northern latitudes and where there's low vitamin D. And so vitamin D is really important for everything, including autoimmune disease. And it's really not hard to do. You really could make a dramatic difference by just getting people's levels of vitamin

D up to 45 nanograms per milliliter. And that would literally lead to 400,000 fewer premature deaths a year. That is no joke. There was one study that showed that if your vitamin D levels were low, you were 75% more likely to end up in the hospital or in the ICU from COVID. If your vitamin D levels were over 50

from one big Israeli study, there was no death, like zero. Now, that may be not true if you keep doing the study and it may be a little bit bigger, there may be occasional deaths, but the point is here that vitamin D is highly protective. So, I think we probably should have a vitamin D mandate in this country. Now, when my patients get their levels up,

they feel better, they have more mood improvements, their muscles recover better, their thyroid works better, their energy is better, their whole system works better. And so it's a really important thing to make sure you get. So how does your body make vitamin D? Now we obviously never had to take supplements when we were hunting and gathering and evolving because we're outside most of the time. And in fact, 80 to 100% of the vitamin D that we need

is created because of exposure to the sun. And when you get a little bit of a sunburn, we call a minimal erythromyldose, which means basically the dose that makes your skin a bit red when you get a sunburn, that might produce between 10 to 25,000 units of vitamin D in our bodies, which is great. The problem is most of us don't get

that kind of sun exposure, and a lot of times we use a lot of sunscreen, which is not necessarily bad. Well, it depends on which sunscreen you're using, but they block a lot of the benefits of getting vitamin D, so you might be out in the sun, but using sunblock and then not getting vitamin D. Now, if you live in a northern climate, you're for sure not getting enough sun and vitamin D. So you might be out in the sun but using sunblock and then not getting vitamin D. Now if you live in a northern climate you're for sure not getting enough sun and vitamin D, especially in the winter. And you're probably not eating a lot of the, you know, porcini mushrooms

and background herring and cod liver oil. Also the other problem is as we get older, our skin does not convert the sun into vitamin D in the way that we did when we were younger. So the average 70-year-old creates only 25% of the vitamin D that a 20-year-old does. Also, depending on your skin color, if you have dark skin, if you're African-American, you basically will produce far less vitamin D and you need a lot more sun exposure.

So most African-Americans are very deficient in vitamin D. I also recommend that everybody supplement. Now, I think it's one of those basic supplements that everybody should get. It makes such a difference. And you should have a level between 45 to 75, let's say. And the only way to know what that is is to test. You need to test and find out what's going on.

And you can guess, but you often will be off. Some people need 2,000 units, I really need 5,000, I need 10,000 units to get their vitamin levels up to the ideal level. And you can do that through your doctor or I co-founded a company called Function Health. You go to functionhealth.com, you can join the wait list

and get testing that actually helps you to get your actual levels, to know what you're doing, to check it over time. I think if you use the code YOUNGFOREVER, you can get in and actually get off the wait list. So try that and see how your vitamin D levels are, but it's important to know and And and often doctors. Oh, don't worry. Just take just take the vitamin D, but you really want to know what your levels are

Also, if you want to get you know sun exposure, the best is 10 to 2 In obviously the summertime 10 to 2 at 10 a.m. To 2 p.m Full body sun exposure for 20 minutes that that will mean you can cover your face or put some luck on your face, but you really wanna have full body exposure. I mean, it only works in the summer and only works if you live below Atlanta. So, I recommend taking vitamin D

and probably two to 5,000 of vitamin D3. It's important to take vitamin D3, not vitamin D2. Most doctors will prescribe vitamin D2, which is unfortunate, but make sure you get the take vitamin D3, not vitamin D2. Most doctors will prescribe vitamin D2, which is unfortunate, but make sure you get the right vitamin D. Again, it depends on your age, your genetics, where you live, how much time you're in the sun, time of year, but if you live in the summer,

I don't need it, but it's actually not true. You need it during the summer, unless you're out there all the time. So check your vitamin D levels and find out what's going on. Now, what about protecting yourself from skin cancer? That's important, right? You want to make sure you don't get skin cancer, particularly on your face. So I think if you want to go out in the sun, great. Use sunscreen on your face. If you want to, you're worried about getting a sunburn and you're really out there a lot, you can use high SPF sunscreen. But you're

going to get vitamin D from your supplements, so you should be okay. The high SPF, it kind of gives people a sense of security that you can go out there and just burn up, but you want to be careful. You don't want to do that. You want to make sure to just moderate your sun exposure, avoiding the high ultraviolet radiation exposures that you can get from prolonged sun exposure. So basically, use sunscreen. And also, by the way, you wanna use sunscreen that doesn't have crap in it,

and we'll talk about that in a minute. So over-the-counter sunscreens are fine, but they're often full of crappy, harmful ingredients. EWG found 80% of the 1,700 products they looked at that were sunscreen had inferior sun protection or had like really weird ingredients like oxybenzone or other parabens. I had a woman once who was in my practice and she had super high levels of toxins in

her urine from parabens and she's like a super health nut and I'm like, what are you doing? What are you exposed to with plastics or chemicals? She said, oh, well, you know, I use a ton of sunscreen all the time every day. And so she had high levels of these toxic petrochemical plastics in her urine that were coming from the sunscreen. A lot of it wasnít getting out of her body, so it wasnít great. Also you should be worried about sunscreen with vitamin A. If you use vitamin A, it actually can make the skin cancer more likely, So I would be particularly careful of that.

But the bottom line is choose good average low SPF sunscreen. Don't rely on it for total protection. Cover your face mostly. And you'll be able to act, go out, and enjoy the sun. So what are the seven strategies I use to get safe sun exposure? Well, don't be afraid of the sun on your vacation. Don't obviously get overexposed, right? Because getting overexposed doesn't just ruin your vacation

and give you a sunburn, it can lead to long-term issues with skin damage and skin cancers and more wrinkles, which nobody wants. So try to get at least 20 minutes of sun exposure every day. First thing in the morning ideally, which the morning sunlight helps trigger your brain to release chemicals and hormones like melatonin and kind of reset your circadian rhythms.

It helps mood, healthy aging. Use scun screen, but only when you need it. And particularly use the safe sunscreens. You can check out Skin Deep, which is a database from EWG. And it's great. Be proactive about protection. So don't overdo it, right? Try to get shade, umbrella, tree, hat, I mean, protective clothing, that's fine. If you money, don't get skin cancer, which I don't want to get. Make sure you cover up.

Sunglasses are important. You don't actually get, obviously sunburn in your eyes, but you get cataracts from prolonged sun exposure without UV blocking sunglasses. So that's important. Don't get burned. Burning is really bad because that leads to more risk of skin cancer. Choose a skin cancer that has optimal UVA protection. Don't do tanning beds.

Get vitamin D, which will help reduce your risk of skin cancer. And there's good evidence that sunblock prevents swamy cells but not necessarily basal cells. So make sure you get skin checks, get your skin checked for cancer on a regular basis every year. Make sure you get a good dermatologist to look at it and they can get things when they're early and they're really not a problem. You don't die from skin cancer except melanoma which is not necessarily sun related.

Also again, make sure you check the ingredients. You don't want to have parabens, petrochemicals, lead, toxins. They all get absorbed in your skin. Go to the EWG website, ewg.org. You can look at the sunscreen guide, the skin deep guide. Also stay hydrated. A lot of us are drinking caffeine, having having alcohol on the beach makes us dehydrated and and that can actually just make you feel crappy and and not make your vacation fun.

Stick to take sunscreen for example this is something you know summertime people wanting to get skin cancer they're putting on scantrine in it and and is it is it okay like should what should we be doing and how do we figure out what's going on I mean a lot of the sunscreens also have compounds that destroy reefs too. There's like reef dice, the coral reefs. So you're not only killing yourself, but you're killing the reefs.

Right. Well, there's a lot of the chemical sunscreens like avibin zone, I don't even know all of the names of them, the chemical sunscreens. And many of those are potentially endocrine-destructing chemicals as well. The flip side is, Mark, I'm one of those people who grew up in the South, had more than my share of sunburns, had my first skin cancer when I was 37.

So I also wanted to slow down skin aging and wrinkles and skin cancer. So we kind of have to say, well, how do you get the protection you want without putting yourself at risk? I personally am a real fan of the Zaykin titanium, the mineral-based sunscreens, or even just a hat covering your skin, staying out of the sun in the middle of the day. I mean, I think there's a lot of other things we can do that are going to be safer for us and safer for the planet. One of my favorite one-stop shopping places to learn more about safety levels and which either skincare or sunscreens, the things we do or don't want is the environmental working group.

And I know you've been a big supporter of their work for years. I think they were some of the pioneers really raising awareness. And what I love about them is they have a safe cosmetics database that you can search by type. You could search sunscreens, or you could search by brand, plug in your favorite brand, and see how it rates to others on their list. If you're living on caffeine, constantly tired, and feel like your stress is stuck on high, there's a good chance you're low in magnesium.

Magnesium is critical for turning food into energy, calming your nervous system, helping you sleep, and regulating your mood. And here's the kicker, up to 80% of us aren't getting enough. That kind of chronic deficiency may contribute to feelings of burnout, occasional tension, irritability, and the kind of fatigue that coffee can't fix. That's why I recommend magnesium breakthrough by bioptimizers. It's the only formula that combines all seven essential forms of magnesium, including glycinate for calm and citrate for digestion.

Most magnesium supplements only offer one or two forms. Magnesium Breakthrough covers them all for deeper sleep, better focus, less tension, and real support during stressful times. If your body's feeling off, this might be the missing link. Try it risk-free at bioptimizers.com slash Hymen and get 10% off your order. As a fat soluble vitamin, vitamin D needs to be absorbed with fats from our diet and then stored in our body, in our fat tissue, in our liver, similar to other fat soluble vitamins like A, E, and K. This episode will help you understand the crucial role that vitamin D plays in our health

and why maintaining adequate levels is super important. Now, vitamin D is best known for its critical role in bone health and in immune system function. It enhances calcium absorption, which is really important. That's how calcium gets in your body with the help of vitamin D. And that's why deficiency in vitamin D leads to bone deformities and things like rickets in children

and osteoporosis in adults. But vitamin D does so much more than just support our bones. It's a powerhouse for our immune system. It helps fight inflammation, it helps reduce the risk of all the chronic diseases which we suffer from, from obesity, type two diabetes, to heart disease and dementia and autoimmunity. And that could go on and on, mental health, depression.

I mean, the list goes on. Now it even plays a role in lowering the risk of autoimmune conditions and reduces your risk of infection. And this is really crazy data, but the COVID pandemic highlighted the importance of vitamin D and immunity with many studies showing that low levels of vitamin D and immunity with many studies showing that low levels of vitamin D increase the risk of severe infection,

hospitalization, and death. In other words, if your vitamin D was low, you were more likely to end up with a severe infection in the hospital or die. Now, beyond bone health and immunity, vitamin D has a lot of jobs, including thyroid and many, many other things. It affects the expression of over a thousand genes.

It's more like a hormone than a vitamin. And it supports the brain really critically by aiding in cognition, helping with memory, mood and depression, and also helps protect against really bad things like neurodegenerative diseases like Alzheimer's and Parkinson's. Vitamin D is also critical for hormonal balance, fertility and gut health, literally everything, everything.

The vitamins are not like drugs that have a single action on a single receptor with a single effect for a single disease. Vitamin D and other vitamins are what we call pleomorphic. They have many, many, many effects in the body and that's what makes them so amazing and they're very safe and effective and they have no side effects

because they're the things your body uses to do its job and so you just need to have optimal levels not overdose obviously but the optimal levels. Now despite its importance many people are really deficient or insufficient in this vital nutrient and they miss out on many of the protective benefits. So let's explore why vitamin D deficiency is so common and how it impacts our health and also what we can do to ensure we're getting enough of this essential vitamin. Now we all hear about the benefits of vitamin D

but what exactly is it and what does it do in our bodies? Well, as I mentioned, vitamin D is a fat soluble vitamin which means it must be absorbed with fats from our diet like other fat soluble vitamins like A, E and K and it's stored in our body's fat tissue and liver. So let's sort of dive into bone health and immunity, which are the most well-known effects, but there's many, many more.

Vitamin D is obviously known for its critical role in bone health and in supporting immune function. And how does it work? Well, it enhances the absorption of calcium, which is why deficiency is linked to all kinds of bone deformities like rickets and osteomalacia, which is bone softening, and osteoporosis in adults. In fact, if you want to do a cheap vitamin D test,

you just stick your thumb on your shin and push in hard, and if it hurts, you are likely either insufficient or vitamin D deficient. So just try that now, but not if you're driving, okay? In addition to bone health, vitamin D is a superpower house when it comes to supporting our immune system and fighting inflammation. That's why having sufficient levels is associated with lower risk of so many chronic diseases that are all inflammatory diseases. Things like obesity,

type 2 diabetes, heart disease, and so forth. Also, diseases like autoimmune disease, which includes multiple sclerosis, rheumatoid arthritis, type 1 diabetes. But that's not all. Vitamin D is also a key player in reducing the risk of infection. In fact, if your vitamin D level is adequately elevated, it means in the high normal range, not like what the reference range is, but optimal levels, your risk of getting the flu is 75% lower. That's better than the flu vaccine, guys. So this is really cheap, really inexpensive, and it's really safe. It also helps support our immune system and it protects us from just getting sick and colds. And I get my vitamin D levels up and I never get sick. I really, I don't remember the last time I had a cold because

I just take my vitamin D every day and it just does its job and I'm good to go. Now it does this by modulating the production of immune cells and immune molecules are messengers like cytokines. It regulates T cells and B cells. T cells are your immune cells like your lymphocytes and at your killer cells. B cells make antibodies and these play a critical role in our innate and adaptive immune systems. The ancient immune system which is the innate immune system has been there forever and is sort of a general all-purpose but not specific immune system. And the adaptive immune system is really the specific targeted immune system that sort of makes laser guided bombs.

Like you get antibodies to COVID, well, that's a target against COVID. That's what your immune system does. Now the COVID-19 pandemic shined a very much needed light on the impact of vitamin D on immunity. We learned from countless studies that low vitamin D levels increase the risk of severe infection, hospitalization, and death.

This is just scratching the surface. If you look at the data, it was quite striking. So out of Israel, if your level of vitamin D was over 50 nanograms per deciliter, we're going to get talking about what the level should be. That's probably the optimal level. If your level was 50 or more, your risk of death from COVID was zero, like zero. That's amazing. And if your vitamin D levels are low,

you were 70% more likely to end up in the hospital, end up in the ICU or die from COVID. Now, what else does vitamin D do for the body? Well, it's an incredibly powerful vitamin that affects, as I mentioned, over 1,000 genes. We're gonna put all the links and the references of everything I'm saying in the show notes, so don't worry. Now, most people agree it's actually more of a hormone

than a vitamin, it impacts all kinds of cellular functions across all of our organs and tissues. For example, the brain uses vitamin D to support cognition, to mood and mental health. You've heard of seasonal affective disorder or SAD or the winter blues. Well, that's vitamin D deficiency, folks. That's why they say use a UV light because UV light makes your body make vitamin D. But you can also just take vitamin D.

It also protects against neurodegenerative diseases like Alzheimer's and Parkinson's. It also plays a role in hormone health and fertility and our gut health is also affected by beneficially modulating the gut microbiome and enhancing overall digestive health. And just more, there's just more. It's a long list, I guess it'll be a 10 hour podcast. There are whole books written on this,

but I encourage you to check out Michael Holick's work in his book, he's quite good on this topic. And Robert Heaney, they were both really profoundly deep vitamin D researchers, so if you wanna get geeky on it, you should go check that out. Now the problem is that many people are deficient or insufficient. The difference is what's the reference range of the lab

versus what's the optimal range, right? So if you take a bunch of Americans who are all working, living inside, who put on sunblock all the time, and who don't really get much sun exposure, the quote normal level in the population of vitamin D will be on the low side, like 20 or 30. That's not the optimal level.

What if we're all running around like hunters and gatherers in our loincloths and out in the sun all day, and we're getting all the vitamin D we need, we'd probably be like 50 to 100 lifeguards who are sitting out on the beach all day and we're getting all the vitamin D we need, we'd probably be like 50 to 100 lifeguards who are sitting out on the beach all day, they get levels of up to 250 and it's safe for them. That's just from the sun, not from taking vitamin D supplements.

So when you're insufficient or deficient, you're missing out on all the protective benefits. Exactly how many people are really deficient? Now, hang on your hats folks, because I think it's about a billion people. Now, the references are in the show notes, but a billion people, that's a lot of people. In the US alone, 70% of people have suboptimal levels,

which is a lot of people. That's seven out of 10 people. And I think partly that's probably why COVID hit us so hard, aside from the fact that we're all metabolic and healthy and have chronic disease, which didn't help, but all that partially is linked to vitamin D insufficiency or deficiency. Now, this widespread deficiency highlights just how important it is to ensure that we're getting enough vitamin D for optimal health. So what are the symptoms? How do you know if you're deficient? Well, there's some clues, right? You might get sick a lot. You might have muscle aches or joint pain. In fact, one of

the things that vitamin D deficiency can cause is fibromyalgia or muscle aches and pains. Not just soft bones or painful bones or aches, but actual painful and impaired muscle function. You might have a history of a fracture, osteoporosis or brittle bones, right? That can be a clue. You might have things like depression or anxiety or mood or memory issues. Maybe you'll have also hair loss, fatigue, hormonal balances like PCOS. In fact, vitamin D is so critical for thyroid function, without vitamin D, you can't actually bind the thyroid hormone to the receptors on the nucleus of your cells and do what it's supposed to do. And so you end up with poorly functioning thyroid.

So the list goes on and on. Now, if any of these symptoms sound familiar to you, you might want to get your levels checked. In fact, scratch that. Everybody should get their vitamin D level checked. Just baseline. It's like your blood pressure or your blood sugar or your cholesterol, you got to know your vitamin D level.

But for some silly reason, I don't know, because maybe nutrition is considered a four step child of medicine, vitamin D is not included in your regular routine lab tests, so you're probably gonna have to ask your doctor for it. Now, this is partly why I started Function Health. Now, this is a company I co-founded, which is a health platform that allows people

to get access to their own lab data. We test vitamin D and lots of other biomarkers, over 110 biomarkers to give you a full picture of your health. We look at nutrients, not just vitamin D, but lots of nutrients, hormones, cardiometabolic health, and we can see where you're out of whack. We see that 67% of people are deficient in one or more nutrients at the minimum level for deficiency disease, not the optimal level for health. So when we broaden the aperture and we look at what the optimal levels

are, it's probably like 90% or more. Now conventional medicine just doesn't look at this. They look at biomarkers in isolation. They don't do a full workup of your hormones, your lipids, your autoimmune markers to get a deeper look at what's going on beneath the surface. So this is really why iCo founded Function Health, to help you get access to your own lab data. So to get a deeper look at what's going on beneath the surface. So this is really why I co-founded Function Health, to help you get access to your own lab data. So to get your vitamin D levels checked and start becoming a CEO of your own health, just go to functionhealth.com forward slash mark

to skip the 300,000 person wait list and learn more. All right, so let's talk about vitamin D and diseases. What chronic diseases are associated with vitamin D deficiency? Now there's this really important concept that I learned from Dr. Robert Heaney, who was one of the leading vitamin D researchers. And he wrote an article, you can look it up,

and we're gonna put it in the show notes, called Long Latency Deficiency Disease. And let me just explain this for a minute. These are nutritional diseases that don't occur in the short run, but occur in the long run. For example, if you are vitamin D deficient in an acute way as a child, you get rickets. If you have chronic low levels of vitamin D, not enough to get rickets, but you might need 30 units a day to not get rickets.

You might need 5,000 units a day to not get osteoporosis. You might need more than000 units a day to not get osteoporosis. You might need more than 10 times the dose. And in the case of vitamin D, the long latency deficiency disease is osteoporosis, or it could be even things like heart disease, or cancer, or diabetes, or dementia, right? These are long latency deficiency diseases

that develop over a long period of time due to chronic nutrient deficiencies, not just vitamin D, but all kinds of nutrients. Now these might not show symptoms right away, but over time they lead to serious health issues like osteoporosis, cardiovascular disease, cancer. So maintaining adequate levels of your nutrients is really key for long-term health and disease prevention.

So let's discuss a few of these chronic diseases and their association with these suboptimal levels. And I'll go through the reference ranges, I'll explain all that in a minute, but I want you to just get, this is, no, no, there's a reference range which is what's normal for a population. If you were a Martian and landed in America today,

it's normal to be overweight, right? Because 75% of us are overweight. Not optimal, it's just normal. Which is a statistical calculation based on two standard deviations from the mean in the population. Has nothing to do with what's optimal or biological optimization. It just has to do with what's normal in a population, right?

So vitamin D helps protect against cancer, which is a big one. It does this by regulating the growth, the fission, and killing of bad or damaged cells. We call this apoptosis or programmed cell death, basically where cells sort of have a self-destruct button, which is good. You don't want your old decrepit cells around, you wanna get rid of the old ones and recycle the parts and build new ones. It also enhances immune function

and it helps reduce inflammation, which is decreasing the likelihood of all sorts of things, including cancer, which is an inflammatory disease. And because of this not having enough vitamin D is associated with certain cancers like breast, prostate cancer, ovarian and lung and pancreatic cancer and even skin cancer. On the other hand, that means that adequate levels of vitamin D are associated with protection which is supported over and over again in the research. For example, a study in 2018 found that women with vitamin D levels of over 60 nanograms per milliliter, and just to be clear, most reference ranges on labs out there are 20

or maximum 30 nanograms per milliliter. We're talking about double that, right? At least double or even triple that number. If they had a level over 60, which is where I think most people should be, they had an 82% lower risk of breast cancer incidence compared with those who had a level of under 20 nanograms per milliliter. That's a big deal. In another study, breast cancer patients who had a higher vitamin D level at the time of their diagnosis

had a significantly lower risk of death related to their cancer than those with lower levels. So even if you get cancer, your likelihood of dying from it is lower if your vitamin D level is adequate. I'm just talking about COVID-19, but I'll just tell you, this is anything, any infection, any virus, any bacteria, whether it's the flu or a cold or COVID-19. But I just tell you, this isn't anything, any infection, any virus, any

bacteria, whether it's the flu or a cold or COVID-19 or monkeypox or whatever the latest and next variation of a virus that we have to deal with the next pandemic, you got to get your vitamin E levels up. This is life and death folks. Do you have a question about my favorite books, supplements or recipes? Then sign up for my free Mark's Picks newsletter at drheimann.com slash Mark's Picks, where I'll share all of this information with you and so much more. You'll get emails from me every Friday

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I'd love to hear your comments and questions. Don't forget to rate, review, and subscribe to The Dr. Hyman Show wherever you get your podcasts. And don't forget to check out my YouTube channel at Dr. Mark Hyman for video versions of this podcast and more. Thank you so much again for tuning in. We'll see you next time on The Dr. Hyman Show. This podcast is separate from my clinical practice

at the Ultra Wellness Center, my work at Cleveland Clinic and Function Health, where I am Chief Medical Officer. This podcast represents my opinions and my guests opinions. Neither myself nor the podcast endorses the views or statements of my guests. This podcast is for educational purposes only and is not a substitute for professional care

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