Deconstructing Vitamin D

Before phototropic plants began bending toward sunlight, before jellyfish developed ocelli, the light-sensing organs that allow them to distinguish between up (sunlight) and down, before the bikini-clad beach denizens began tanning en masse, and before the first house cat followed the sliver of sunlight around the room all afternoon, our primitive, microscopic marine forebears were flourishing by converting the sun’s energy into chemical energy usable by biological life. You’re probably aware of photosynthesis, the process by which plants, algae, and other organisms do it and produce byproducts like oxygen, but even the unicellular archaea that do not produce oxygen utilize sunlight for energy. And if you aren’t obtaining energy directly from the sun, you’re probably eating the organisms that do. Either way, sunlight directly or indirectly supports all life (well, except for the chemoautotrophs living in deep sea hydrothermal vents feeding off of inorganic energy sources like iron, ammonia, or sulfur).

Humans don’t directly consume sunlight, though. We aren’t breatharians or walking, talking photosynthesizers. Sunlight might feel good and it might brighten up our moods, but we don’t consume it for metabolic sustenance. It does, however, provide the raw material for the 7- dehydrocholesterol in our skin to manufacture the ever-important vitamin D3, or cholecalciferol.

For some organisms, like the naked mole rat with its natural, “preferred” vitamin D deficiency, vitamin D is unimportant. But for most, including man, vitamin D is vital. You might even say it’s the most important vitamin of all. It’s not really even a vitamin, in fact; it’s a secesteroid, a hormonal precursor that closely resembles steroids like cortisol, testosterone, and cholesterol. Most vitamins are exogenous and stem from outside sources. Vitamin D is a different sort of “vitamin.” We mammals make it in-house.

Vitamin D is essential to us. As an equatorial people, we homo sapiens all spent well over half our collective development time bathed in tropical sun, almost year-round. Those of us who flitted off to the South Pacific and other equatorial regions got plenty of the stuff, too. Northerners even developed fair skin with less melanin, which maximized their ability to produce vitamin D from less sunlight. We’ve clearly evolved with the availability of sunlight – and therefore vitamin D3 – as a central stressor to our development.

As you know, the Primal Blueprint is about looking for that perfect storm of evolutionary concordance and modern scientific confirmation. I try to find the eye of the storm and stay there. When it moves, I move with it.

To evaluate whether a food or nutrient or behavior is suitable or not, I:

  1. Check out the anthropological records. I look at the historical legacy and ask some questions. Is there evolutionary precedent? Did our ancestors have regular, spotty, or zero access? Clearly, we did, having spent the bulk of our evolution on the equator with regular access to sunlight.
  2. Check out the current science and ask more questions. What does the epidemiology show? Are there any randomized controlled trials on the subject? Were they animal studies or human? There is quite a bit of data. Here’s a small taste, and I’ll address more of it tomorrow.

Vitamin D checks out on all levels. We’re not just talking about some exogenous substance which our ancestors may have occasionally come across and which may confer benefits, like bone marrow or polyphenols. This is vitamin D, the active form of which – called calcitriol – is produced in our livers in response to cholecalciferol derived from UV-B radiation. That’s sunlight, a resource readily available to our equatorial ancestors, the importance of which is indicated by the presence of naturally-occurring vitamin D receptors in the body’s cells.

Our bodies clearly consider it essential, but why? What does it do?

  • It regulates the levels of calcium and phosphate in the bloodstream, and it promotes the mineralization and growth of bones, working together with calcium, vitamin A, and vitamin K2. Severe deficiency can cause rickets.
  • It plays a massive role in the immune response, activating and “arming” the killer T-cells for defense against infections and bacteria.
  • It modulates the expression of genes that regulate cell proliferation, apoptosis, and differentiation, suggesting a potential role in cancer incidence. Epidemiology suggests links between vitamin D deficiency and most cancers, including breast, colorectal, and pretty much all the big ones.
  • It reduces systemic, chronic inflammation.

For something as readily available on any given sunny day, it’s also, surprisingly, in short supply these days. We’re told to avoid the sun at all costs or, if we absolutely must venture out into the light, to apply a layer of sunscreen so thick and physically impregnable that an equal amount of something as inert as lite mayo would be just as effective. Between office jobs without a view, window panes that allow UV-A but not UV-B rays, fleshy embarrassed physiques that never see the light, chubby kids who wear t-shirts to go swimming, and even widespread burqa usage in certain regions, humans just aren’t giving their skin enough opportunities to create vitamin D3. And if it’s an essentiality, it’s probably best to provide your body plenty of opportunities to make (or consume) it.

But what’s the best way? Sun? Supplements? Diet?

Tomorrow, I’ll discuss how to rectify this potentially massive problem.

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TAGS:  prevention

About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.

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56 thoughts on “Deconstructing Vitamin D”

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  1. My best friend keeps telling me that skin cancer is not really a big concern even for us lighter skinned folk.

    After doing a bit of research, I have to agree to the basic idea. One of the cancer society’s stats is that 5 sunburns during your life double your risk of skin cancer.

    While about 75,000 people in the U.S. will get skin cancer this year (and that is out of how many sun worshippers out there?), only about 12,000 will die of it, which is about as much as things that seem to scare us a lot less (like bladder cancer). That is, unless Mark wants to write about the Primal way to protect your bladder.

    1. Folks there is NO WAY anybody will get skin cancer from the sun !

      I am a central european mutt (mother is from Finland, Father is from Austria) and our entire family literally soaks (or burns) in that sun as soon as it comes out in spring. My father had so many sun burns he is now permanently tanned, even during winter times.
      Europeans bathe in the sun every year without sunscreen and I have never heard of anyone getting skin cancer.
      One old lady i knew that was one of my teachers wife caught skin cancer – guess where? – on the bottom of her foot!
      I moved from Central Europe to the sunny state of Idaho and have been baking in the sun ever since.

      Here is what i think causes skin cancer:
      1. exessive amounts of chlorine (pool water)
      2. Consumption of vegetable oils that are deposited under the skin and oxidize in the sun. (age spots anyone? That is what causes those, not the sun…therefor cooking with animal fat is the healthiest)
      3. All sunscreen products (and all other lab produced lotions, creams, …)

      Go out and enjoy the sun 🙂

      1. That was a scary post. Please don’t suggest to people they jsut languish in the sun as much as possible. Do your research.

    2. Dare the hardcore sun worshippers to come down to NZ and bake in the hot sun during our summer (Jan – Feb). I GUARANTEE you will get burnt!

      The sunlight here is stronger than much of Europe or North America (clearer skies, higher UV levels with the hole in the ozone etc). Vegetable oils and chlorine has nothing to do with it!

  2. I agree that Vitamin D is essential in many ways. One thing that may be under appreciated or unknown is that the UV component of sunlight may also have health benefits.

    This is a link to a news story about a provocative new research study that actually decoupled Vit D and UV in an animal model of MS. Only the UV group showed improvements, not the matched Vit D group.,_not_vitamin_D,_might_limit_multiple_sclerosis_symptoms

  3. I can not wait till tomorrows post. My Father told us kids to slather on sunscreen during all years of my childhood. I have learned better over the past few months, especially over the past 2 since being primal.

    I am out in the sun a lot as I take walks throughout the day and LOVE golf to death (especially now since I shot in the 70’s for the first time in my life this past Saturday). I also love to hike, play on the beach, tennis… pretty much everything outdoors!

    I enjoy staying inside when its too hot for me. And I Know when I get burnt…

    If I am red and it hurts then I got too much sun. Otherwise I got the perfect amount… at least that’s what I believe these days.

    Oh, and just like many other primal people claim… when you go primal you burn less easily!!

  4. Can’t wait for tomorrow’s post! I’ve been supplementing with Carlson’s D-drops, about 4,000-6,000 IU daily, and definitely noticed a lift in my mood during the winter months. I’m wondering what will be appropriate for the summer months, though I don’t go swimming all that often, and therefore don’t get much full body exposure to sunlight.

    I’ve never been to a tanning salon, but I’m wondering what your take will be on the claims that we can get vitamin D from tanning beds.

  5. iv’e been primal for 7 weeks. (feel awsome) heard all the hub bub about not burning. A 3 hour road ride in the sun still wreaked havoc with my forearms (the tops). I assume that the burn would have been much worse had I been eating & living with CW. if you think explaining primal food plan is to others is tough, try explaining the whole vitamin D / no sunscreen thing.

  6. The sun is very healthy! Sunshine always makes me feel better and makes me want to be right in the midst of it getting out and doing something fun! The ozone layer is not what it used to be. I always put on SPF Sunscreen 30 and i reapply about every 2 hours as it does wear off.

  7. Nothing makes me feel better than exercising in the sun. It is something we should all do more of.

    1. @ Nathan, i totally agree. The sun has a way of “energizing” me and puts me in a great mood!!

  8. I’ve been supplementing with 4,000 IU of D3 for about a month. After spending quite a bit of time in the sun the last couple weekends, I noticed I didn’t burn nearly as badly as I usually do – in fact, I just turned a bit red the first weekend.

    1. That is the exact same as me. I have been supplementing with d3 4,000 for 3 months. I work outside all day as I am a landscaper. Oh, and I am a red head with pretty fair skin. In the past I would burn and peel a couple of times a year. Now this year is totally different, I have not burned or peeled…my skin is tanning and not burning at all!

  9. I’m amazed by the amount of regulation of the bodies function and hormones that VitD and K2 help regulate. Can’t say I haven’t felt better after a good workout in the sun (in comparison to be stuck indoors). I personally hate sweating sunscreen, so this is fantastic. Like everything else though, i’m sure its all good in moderation(?). Thanks for all the great info, one more excuse to get to the beach more.

  10. Long time no comment. . . I’m looking forward to tomorrow’s post. One question I’ve wanted to ask for quite a while. I get plenty of time outside in the sun on the weekends, but my time outside during the week is before sun-rise and later afternoon/evening. Is D ‘stored’ by the body after a couple of days of sun exposure? I don’t bother with D3 supplement on the weekends, but should I be waiting until Tuesday/Wednesday to start taking D3 because of exposure over the weekend? Or do I need to supplement any day that I can’t be outside during ‘peak’ sun exposure?

    Jennifer (she of the Kitchen Sink Salad)

  11. I did a bodyweight/hiit workout in my backyard a couple weeks ago (before it snowed again – darn Alberta weather) in the warm sun, barefoot and with just shorts on – amazing! The dogs and I will often catch some rays together on the back deck in the morning. Very nice indeed.

  12. Would be keen to hear how to get more vitamin D in Winter when you live in a place where it tends to rain non-stop for days on end.

  13. Note there is a certain small fraction of the population that suffers from defects in the VDR receptor (vitamin D receptor) which causes them to overconvert the storage vitamon D (25,OH) to the active metabolite form (1,25 OH). This is believed by some to cause various autoimmune disorders.

    For those that can not raise their storage vitamin D to normal levels (the type normally checked in blood testing), it is worth testing the active metabolite.

  14. Great intro into the benefits of vitamin D. I can personally attest to the immune boosting benefit of vitamin D. Three weeks ago both my wife and I got strep throat. I added sublingual vitamin D and recovered a couple days faster than my wife.

    I am a believer of a getting sunlight, or at least adding vitamin D to your daily routine!

  15. Hey Mark,
    What is your opinion on Dr. Mercolas research that shows a high ratio of vitamin A to vitamin D blocks vitamin D absorption and that most of today’s supplements contain WAY too much vitamin A? Your supplement included…

    1. I agree with Mercola’s point here. But note that my Damage Control Master Formula does NOT contain too much vitamin A. It has 2500 IU of retinyl acetate (which is true vitamin A. That’s only 50% of what the USDA says is the minimum required for health. The rest is beta carotene, which is NOT vitamin A and which your body will only convert to vitamin A if it needs it. Otherwise, beta carotene is an antioxidant. Oddly, the DSHEA law requires that you put beta carotene under vitamin A on the label, so it looks like there’s too much A when there’s actually not.

  16. Since I’ve started taking vitamin D I’ve been much more of a happy person 😀

  17. Solid post except for the title Mark. The misuse of the term deconstruction has become ubiquitous. Why not just say “dissect” since that is what is meant by 99% of the folks who (mis) use the term (in titles at least).

    “Deconstruction” is the dismantling of a communication structure (not of overt content; not latent meaning) for the purpose of demonstrating engrained assumption. (Again, not in the “content” but in the “system” itself, typically linguistic or visual.) Often times this involves reorganizing composition in seemingly absurd ways in order to achieve this goal.

    I guess “Dissecting Vitamin D” just isn’t as cool sounding. (Hey Woody Allen got it wrong too…)

  18. Great timing for an article on Vit D…

    I too enjoy spending plenty of time outdoors, and in the Alberta spring, that has been limited this year, however I have also been doing some reading/listening to articles on Vit D and many people say to supplement with upwards of 10,000 (even 20,000) per day until you get your levels back to optimal. I have been taking 5000iu per day, and I also eat sardines 2-3 times a week, as well as other cold water fish on occasion so my level should be pretty good.

    Having said that, I have yet to be sick since taking the vit d and I work at a 2200 person high school, and have toddlers of my own who have all been sick over the past year.

    It may be due to many things including exercise, nutrition and stress reduction, but i don’t plan to ditch the Vit D because it seems to be working for me.

    Grassroots Health has plenty of information on Vit D and the latest research for those interested.

  19. It’s kind of funny what CW will tell you on this….I just had a pretty extensive blood test done. It told me my cholesterol was fine (but my doc has had me on statins for several months b/c the last check said it was high) but that my Vitamin D was low. Did a little research. Come to find out that statins negatively impact your body’s synthesis of Vitamin D because of how it interacts with the cholesterol, which helps synthesize Vitamin D. Ergo, my doc wants me to take statins to lower my cholesterol, but now she wants me to take Vitamin D supplements to increase my Vitamin D because the statins, which she prescribed, caused it to drop!!

    Next thing you know, she’ll be telling me to take No-Doze to counteract the sleeping pills she wants me to take. haha.

  20. My mood since it has been warming up and I can get outside every day has lifted 10 fold. I have been supplementing with Vit D (sporadically), hitting the tanning bed about once every 1-2 weeks…but nothing replaces getting outside in the actual sun. I am so glad to be working at home instead of the cube farm anymore….if I need a break, I go out and relax on the deck, pull weeds, tend my plants, or go for a walk. Best productivity boost around.

    Looking forward to tomorrow’s article….being at high altitude, the fine line between enjoying sun and getting lobsterfied is a tough one here. Hoping for some great tips!

  21. I’m glad I caught your post, I was JUST about to go to the store to get some vitamin D supplements. Because my job (navy) doesn’t allow sufficient sun. I can wait another day, it’s not like I’m going to suddenly drop de-… 😡

    1. ugh are you in a submarine or something? That would stink.

      My husband is in the Navy too but he’s a pilot so really flying up there near the sun… but then again he’s completely covered from head to toe. haha. I’m curious to know what his 25-OH(D) serum levels are!

  22. I just read in a recent issue of Men’s Health that too much sun exposure actually starts to inhibit your body’s ability to make Vitamin D. Any truth to that?

  23. I’ve had clients complain of moodiness and lack of energy and when I have them supplement with a good vitamin D their symptoms tend to go away. In fact, I don’t go a day without it, especially in the winter since I am so sensitive to having little sunlight for so long.

    Can’t wait for tomorrow’s post!

  24. Looking forward to tomorrow’s post. I always feel better when spring rolls around and I can get some sun on my skin. My mood lifts and I have more energy. And I’ve always felt that slathering chemicals on our skin (spf lotions) and then baking it in the sun can’t be very good for us!

  25. Yes, you may increase risk for skin cancer from sun burns, but no D advocate is saying go out and get burned — 20 mins three times a week can load you up with D.
    Beside the skin cancer you get from exposure to sun is highly treatable. The skin cancer you get from not enough sun is highly deadly.
    Dr. Holick’s new book is amazing. You will be fully informed on this subject if you read it.
    Great article!
    Get on the D train!!!

    1. re. skin cancer & sun burn,
      i read a study that, ironically, people who’ve been burned (moderately) are less likely to get skin cancer than people who never go out under the sun hence never get burned.
      perhaps it’s sort of building up the resistance?

      (i’ll see if i can find it.)


  26. Having just been diagnosed with a moderate Vitamin D deficiency, I am really looking forward to your follow-up article.

  27. I tell everyone about d3, sadly not many listen to me. I got into a heated argument with my uncle last weekend. He told me there is no way I know more than a doctor about anything. I shut up after that.

  28. Yes, it’s hard to talk to anybody if you mention something that goes against the grain. (CW, mass brain washing)
    There are plenty of articles in the press now about slathering on the sun cream. Here in Ireland the sun is very shy, you might see it for a week or so and that’s it, but people prepare for their holidays abroad in Spain or Italy so the ‘good advice’ is timely.
    The rate of skin cancer has almost doubled in Ireland over the past 10 years. Why? It’s not because people don’t apply enough sunscreen or often enough, I think.
    “I wouldn’t leave the bedroom without factor 50 – summer and winter,” asserts Dr Rosemary Coleman, consultant dermatologist in a private clinic , admitting that her job removing skin cancers every day leaves her inclined to such a strict regime.
    “There is a misconception that you only pick up cancer on two-week holidays in the Canaries – but so many cancer patients have never left the country,” she points out. Hmmm. ‘pick up cancer’?!
    And she recommends taking vit D supps if you always use sun creams, like her, cover with a hat and clothes and stay away from the sun from 11 to 3.
    It doesn’t make sense from the point of view of evolution. Is there something wrong with the atmosphere? Peasants working in the sun all summer get very brown arms and faces but I never heard anybody talking about skin cancer.
    I hope Mark is going to talk about optimal sun exposure for people who avoid omega 6 and grains.

  29. It’s crazy how we are so afraid of the sun. Just like everything else in life, as long as you don’t overdo it, there’s nothing to fear. It’s something that just cannot be replaced in pills.

  30. Mark,
    No doubt Sunlight and Vitamin D is good for us, but this article concerned me a couple of days ago:

    It basically states the optimum Vit D levels are 30-35 ng/ml, much less that the recommended figures (for example, vit d council recommends no less than 50 ng/ml). Even vit d levels above 80 ng/ml could increase cancer risk.

    I enrolled in a 5-year vit d. study at At 3.000 IU/day, my vit d. levels were 33 ng/ml. I increased my dosage to 5.000 IU/day to get above 50 ng/ml, but now I am wondering if this is good for me.

    What do you think ?

  31. I have had skin cancer (6 years ago) and was told stay out of the sun and use a sun screen! I am so oily and by the end of the day people can fix their hair in the shine of my forehead. I think I am going to break from sunscreen and see what happens. I agree that baking a chemical in our skin just cannot be good!

  32. Great post, i think a lot of hype and hysteria needs to be debunked. I love the sun and will always try to catch some rays when its out but putting sun cream on to protect your skin is an absolute must! Skin cancer’s a serious danger but as long as your sensible i think even the palest of us can enjoy the sunshine