Vitamin D and the sun habits of our ancestors


How much time did our ancestors spend in the sun? And does it matter for your health today?

A new study provides an interesting clue.

From sunny Africa to the dark north

Our human ancestors emigrated from eastern Africa and spread across the entire planet. That often meant that the sun became much weaker. Since vitamin D is produced by our skin when in strong sunlight their levels of vitamin D dropped rapidly when moving north, which may have led to severe health problems.

In an extremely short time, evolutionary speaking, the ancestors of northern people developed lighter skin. They rapidly shed their built-in sun protection, likely to catch all the sun and vitamin D that they could.

In not-so-sunny Sweden, where I live, a lot of people have severe shortage of vitamin D during the winter, despite having light skin. Statistically such deficiency is correlated with just about every disease there is. Such correlations doesn’t prove that the deficiency leads to all these diseases, but it’s possible that it contributes.

What is normal?

How much vitamin D is “normal” to have in your blood? That’s a common question. According to my lab between 75-250 nmol/L is normal, and below 75 is considered a deficiency.

  • (Divide by 2.5 for values in ng/ml, i.e. 30-100 ng/ml would be considered normal)

This means that all the patients I’ve tested during the winter in Sweden are deficient, if they haven’t travelled south or taken a vitamin D supplement. Extreme deficiencies of 20 or less isn’t uncommon. The lowest I’ve seen is 14 nmol/L.

These extreme deficiencies have often been tired patients, sometimes with a history of winter depressions. Taking supplemental vitamin D has several times led to remarkable recoveries within a few weeks. Well done trials have also shown significant such effects.

The answer

A study of traditionally living people in sunny East Africa gives us a clue to what’s normal. These people all have dark skin, built in sun protection. They spend most of the day outdoors but avoid strong sun when they can. Perhaps their skin and sun habits are similiar to our ancestors (who lived in the same environment).

The average vitamin D level was 115 nmol/L (46 ng/ml). The lowest level found was 58 and the highest 171. Here is the study:

How do we get vitamin D during the winter?

For those who don’t spend their days outdoors in a sunny climate there are three good options to get vitamin D:

  1. Strong sun (travelling south or using a tanning bed with the right wave lengths)
  2. Eating fatty fish (350 grams daily may give you 2 000 units)
  3. Supplements (the cheapest, easiest way)

Personally I’ve been taking 4 000 units daily (recently increased to 5 000). I skip it during sunny summer times. This fall my vitamin D level was 95 nmol/L.

Less than an average Maasai but not too bad.


  1. Heidi P.
    I have been thinking about this lately, so thank you for posting about it. I'm off to go purchase a supplement. (We have sunshine here in Idaho, USA, but it is too cold to expose your skin to it.)
  2. Lester
    Here in the UK, vitamin D tablets are sold in micrograms. The ones I bought last week were 25 micrograms per tablet. How many of these tablets per day equate to a reasonable supplement? According to the packaging, it's one per day. I suspect that is far too low. Thanks
  3. Jonas Gunnarsson
    25 micrograms = 1000 units so four or five of those would give you the docs doses.

    Also, part of the problem is "strong" sun. Rule of thumb: if your shadow is longer than you are tall, you're not producing vitamin d.

    I also take 4000 units daily.

  4. Dr. Davis says that the tablet form of Vitamin D Supplements does not provide a useable form of Vitamin D. He recommends the oil filled gel capsules. Do you agree?

    What's the upper limit of a safe dosage?? My Vitamin D was 40 on 2000 units/day of Vitamin D, I upped it to 6000 units and now my husband is certain I'm going to die of an overdose (I'm not worried). My doctor only recommends 2000 units/day and I fall "within standard range" (25 to 79 ng/mL) according to the hospital's lab report, so the doctor doesn't think it's low at all.

  5. Sorry, cannot edit my post, but I see the 40 does fall within the normal range when converted to ng/ML.
  6. Carol
    Vitamin D is a fat soluble vitamin, and that's where the recommendation comes from to have it in the oil filled gel capsule form. However, I take the tablets with fatty foods-always present in a LCHF meal- so there will be fat to carry the tablet Vitamin D into the system.
  7. I watched a programme the other day (Time Team) where they were talking about how people lived in pre-Roman round houses. Basically they spent most of their time outside only going in to sleep. Presumably when the weather was bad too. Thinking of myself, I spend long periods in doors these day. Need to get outside more I think.
  8. Nads
    With all the "sun safe" messages in Australia people don't go outside much, and particularly don't let their children go out. So I'm sure most people would be Vitamin D deficient, despite plentiful sunlight. I've heard that just about all obese people are Vit D deficient because it's all stored in their fat. Which is why they feel great once they start to lose weight and their Vit D gets released from the stores.

    Here's a really good interview about Vit D deficiency from an expert who got kicked out of a uni in the US because he didn't toe the line about staying out of the sun.

  9. Henk Poley
    Anybody knows if some company is also adding D3-sulfate nowadays? And then, what would be a good ratio?
  10. Jaime
    I take at least 5000 IU during the winter, and up to 20,000 IU to load up if I see any signs of getting sick. Many researches have found that people can produce about 9,000 - 10,000 a day just by being a long time under the sun, and they obviously not get any overdose, so I don't care when people say that 5,000 is too much. The highest dose that have been documented to produce overdose is 40,000, and it took many weeks before any symptoms arose. Even in cases with up to 1,000,000 for over a week caused no permanent damage after discontinuing the intake.

    There is some interesting research suggesting a link between skin cancer and LACK of vitamin D, which might help to explain why there is more skin cancer in many parts of Scotland than in most sunny Mediterranean countries.

  11. JAUS
    Most sunscreens are terrible at blocking UV-A rays and unfortunately mostly blocks UV-B and by that destroys the body own protection against the sun. Lemon juice is good for blocking UV-A rays and is used traditionally in Mediterranean countries, just spray it on your skin (It wont block UV-B so your body can still produce vitamin D).
  12. moreporkplease
    I'd rather supplement & keep the TiOx sunscreen - years in the sun without protection is extremely aging - I have no desire to look like a ragged leather couch when I'm 40, thank you.
  13. JAUS
    #12 I also take supplements during summer since I don't go outside that much. I'm loosing weight so I don't want my skin to age prematurely cause then it will take longer for the loose skin to disappear. I wouldn't recommend anyone to be more than 1 hour in the sun without clothes (that time is more than enough to get sufficient levels of vitamin D).

    I don't use sunscreens, because of the nasty ingredients they have. I use lemon juice and macadamia oil instead.

  14. @Janknitz Vitamin D3 is a fat soluble vitamin so taking it already dissovled in a oil capsule increases the chances of it being absorbed as does taking your vitamin d with a meal containing fat. Some people report taking it earlier in the day is better for them as taking it at night delays sleep. I think MCT (Medium Chain Triglyceride) oil is the best carrier oil as it's quickly absorbed and easily metabolised. If people have inflamed/damaged] intestines (ie Crohn's disease) they can just bite the capsule hold the oil/vit d in their oral cavity and it will be taken up under the tongue. They could massage the contents of the capsule into skin as well. One of the reasons MCT is used as a carrier in Baby Vit D drops is that it doesn't particularly matter if the baby spits up the drops, by they time it's been massaged into the skin on the face all is not lost.
    MCT is also very stable so it's less likely to go rancid. It's also taste neutral, some of the others taste disgusting if you bite the capsule to check if the oil is not rancid.
  15. With regards this study I think we should be cautious about assuming what may be an optimum 25(OH)D level for dark skinned peoples living under strong sunlight is also optimum for those who evolved paler skins more appropriate for creating higher amounts of vitamin D to enable survival away from the equator.
    I haven't time to find it now but there was a study on vitamin D requirements for African American women in relation to calcium absorption from diet and I'm sure they were able to manage a good calcium economy on a lower 25(OH)D than their paler skinned neighbours. So what may be a reasonable 25(OH)D for a dark skin may be inadequate for some others.
    I try to stay around 60ng/ml ~ 150nmol/l as that gives me a stored reserve of D3.
    If I had to go into hospital, Had an operation, met with some calamity I would be better able to respond to that crisis. We know having surgery drops vitamin D status 40% so having a safety margin stored about your person enables you to withstand that drop and not end up deficient.
    The most vitamin D deficient people before surgery end up staying in hospital longer, have more complications and the long term survival is lower, so being prepared by always being on the higher end of the optimum range may be sensible.
    Useful article here on how to protect your skin from the effects of UV radiation. Really works but takes 8 ~12 weeks so start now for better protection this summer.
    Natural Sunscreen Options
  16. Marie
    I love the image you've used with this post. Where is it from? Who is the artist?
  17. John Myers
    Hey I'm from Idaho, too. My favorite source of Vitamin D in the winter is smoked herring. Of course I have to buy the canned stuff. Or pickled herring, which I can eat half a large jar in one sitting.
    Anyway I've heard that in Sweden pickled herring is traditionally served around Christmas, when the UV radiation is at its lowest. Is that correct? I'm thinking that particular holiday tradition is no accident. Just speculating.
  18. @ John While it's true a kipper(smoked herring) does contain vitamin d3 and is one of the best sources we have to keep in mind that food sources of vitamin D are pretty poor. 120iu per 100g for kipper and Vitamin D 680iu per 100g for pickled herring.
    So while I could get about a fifth of my daily amount from food, if I ate pickled herring daily I'm afraid the fish daily option isn't my choice.
    It certainly was the way the INUIT survived the winter as they did consume fish, seal, game fermented in seal/fish oil in holes in the ground and did make 5000iu/daily/vit d3 from food sources, but I don't think picked fish 3 times daily is going to be readily adopted by most readers here.
  19. Diane
    I heard that Northern Europeans are so light because it takes adequate Vitamin D to carry a baby to term. So we were selected for lighter skin living in our darker areas because of that. I don't know if that is true, but it makes sense and I wouldn't be surprised if it was something like that.
  20. moreporkplease
    Ted, all you sun worshippers talk about ways to reduce sunburn. The real long-term issue is that UV destroys your collagen and elastin and you sag, you get wrinkles, you get hyperpigmentation and liver spots. To be frank, you look like Brigitte Bardot (now, not way back then). It's not a pretty sight. TiOx & Zinc aren't harmful, so a physical sunscreen for me, thanks. There's not a "natural" mixture of nut oils in the world that's going to save your elastin from decades of UV onslaught - sorry, to believe otherwise is just magical thinking. Best wishes to you!
  21. @ moreporkplease
    I still think having an understanding of the process underlying DNA damage by UVA gives one the ability to do something to prevent that damage.
    UVA radiation-induced oxidative damage It costs nothing for all men and post menopausal women to become blood donors
    Iron sensitizes keratinocytes and fibroblasts to UVA-mediated matrix metalloproteinase-1
  22. Stan Slonkosky
    I don't know why doctors don't routinely test patients for Vitamin D3 levels. I only got tested because I asked a doctor for a test when I went in for treatment for a foot ulcer (that was before I started eating low carb). Even though I live in Southern California, I was low enough to be at risk for osteoporosis. I started taking 15,000 IU per day, but have since cut back to 10,000. has been promoting Vitamin D for some time. On the site is a study reporting that no one reached a toxic level (defined as 200 ng/ml) taking 10,000 IU per day. The authors state they believe you'd have to take 50,000 IU per day for a number of months to reach a toxic level. From reading various papers on that site, I concluded that the optimum level is probably around 100 ng/ml or so and there probably isn't much benefit from higher levels than that.

    I think I first became aware of the possibility of a Vitamin D deficiency from the "Security Now" podcast (it's normally about computer security) by Steve Gibson and Leo Laporte. Steve is the inventor of the Gibson Light Pen for the Apple ][ and the author of SpinRite, a hard disk utility. His Vitamin D page is at . Steve (who was born in 1955) tried to increase his Vitamin D by sun exposure, but found, as is the case for most people over 50, that it didn't work for him, so he takes supplemental Vitamin D. I buy the same brand he mentioned (Now Foods) from as they had the best price I could find. Costco also sells gel caps for about the same price per capsule, but they use soy oil whereas Now Foods uses olive oil as the solvent.

  23. vatys
    my anecdote: I'm light-skinned, live in California, and get a little sun most days, so I should be fine, right? I also take 5000 IU of Vitamin D a day, and my Vitamin D levels from my most recent blood test were 52.4 ng/mL (or 131 nmol/L) putting me right smack in the middle of normal range. I can only imagine how deficient I'd be if I weren't supplementing, or even only taking the recommended 400-800 IU a day.
  24. I always thought the dermatologists' scare tactics to never let the sun touch one's skin didn't make a bit of sense. Didn't we, after all, evolve to spend the bulk of our lives outside? I wasn't a bit surprised to find that even with a daily four milk walk outside, I was Vit D deficient.
  25. Yiting
    You suggested sunbeds with the "right wave lengths" as an alternative to real sun. What is the correct wave length?
    Is there not a risk of skin cancer with using sunbeds?
  26. JAUS
    #25 UV-B wave lengths produce vitamin-D, UV-A does not and should be avoided. Don't lay to long on a sunbed, 30 min maximum.

    The winter sun is useless you live quite close to the equator, since the the sun is to low in the sky and the UV-B radiation is to low.

  27. uv lighting guide for reptiles has a lot of basic information that also applies to humans.
  28. Treatment of vitamin D deficiency: divergence between clinical practice and expert advice
    For those who want to believe that UK health professionals are practising evidence based medicine this paper may come a bit of a shock given that over the past 5 years there have been some 2500+ papers on the topic roughly 50 each week far too many for me to keep up with.
    Background Current recommendations for the treatment of vitamin D deficiency vary from calciferol 800 IU per day to loading doses of vitamin D followed by maintenance therapy of up to 2000 IU per day.

    Objective To assess the preparations and doses of vitamin D used to load and maintain patients with serum 25-hydroxyvitamin D (25OHD) <25 nmol/l.

    Methods We examined all requests for serum 25OHD over a 12-month period, from September 2009 to 2010 in southwest Scotland. We wrote to all 33 general practices asking whether they usually started replacement therapy with a loading dose and/or recommended over-the-counter maintenance preparations. We accessed the Emergency Care Summary for all patients with serum 25OHD <25 nmol/l to determine whether they had been prescribed maintenance therapy.

    Results Serum 25OHD was requested in 1162 patients. Levels were <25 nmol/l in 282 (24%) patients, only 173 (61%) of whom were receiving vitamin D replacement therapy 3–15 months after diagnosis. Only four (1.4%) were prescribed a loading dose. One hundred and fifty-three (54%) were treated with cholecalciferol or ergocalciferol and 19 (7%) with alfacalcidol or calcitriol. The median dose of chole/ergocalciferol was 800 IU per day, usually in combination with 1200 mg calcium per day.

    Conclusions We have shown a divergence between clinical practice and even the most conservative expert advice for vitamin D replacement therapy.
    Part of the problem is that UK drug companies won't/can't supply cholecalerol Vit D3 which is the effective human form (presumably the fact a years supply of 5000iu daily should cost no more than £15 is a bit of a disincentive. They have ergocalciferol available but as that works out around £2400 they are reluctant to put people on it.
    The idea that any UK GP could order a bulk supply from reputable FDA approved manufacturers in the USA at cheaper prices than you and I can negotiate is not surprising given the tendency of UK health professionals to rip of the NHS whenever given the chance.

  29. really nice post,
    we all know, nature is the best supplier of all vitamins and minerals. but now a day destroy all the nature energy, read every one this article. i am waiting for articles like this.
  30. Testing Service for 25-hydroxy Vitamin D2 and D3
    £20 to UK addresses, £25 outside the UK.
    I haven't yet used this service but I will do ASP and let you know the results but for UK readers I'm sure this is the CHEAPEST source of 25(OH)D testing and as they also offer this for overseas customers it may well be the cheapest option for other readers.
  31. Lisa
    I just got my latest 25 Hydroxy vitamin D results back today and they went from 79 nmol/L (31.65 ng/mL) to 120.2 nmol/L (48.16 ng/mL). I'm shooting for 125-175 nmol/L (50-70 ng/mL).

    I had increased from a 1000 IU's tablet form to five NOW Foods 1000 IU's in olive oil for three months. I had spread the five 1000 IU softgels out between three meals. We can't get a 5000 IU in Canada or have it shipped from Amazon.

    I also eat canned sockeye with the bones pretty much daily and sometimes fatty fish twice daily plus 200 IU's with my calcium citrate/magnesium supplement and 200 IU's in my multivitamin. All D3.

    My doctor said it is okay for me to continue with this amount but once we have lots of sun should decrease to 2000-3000 IU's daily. I am being retested in six months. When winter returns I'll probably be taking 4000-5000 IU's to maintain a good level. Or at least that is the tentative plan.

    I have had melanoma in 1999 (Clarks level 2 Breslow 0.25mm). She wants me to wear 35-45 SPF but then I won't get the D right? I also have celiac disease.

    Any opinions/comments on my plan?


  32. Dr Cannell of The Vitamin D Council comments here Comparing 2,000 IU/day vs. 5,000 IU/day vitamin D supplementation on this research from New South Wales. Diamond T, Wong YK, Golombick T. Effect of oral cholecalciferol 2,000 versus 5,000 IU on serum vitamin D, PTH, bone and muscle strength in patients with vitamin D deficiency. Osteoporos Int. 2012 Mar 16.

    I'm sure you are aware that New South Wales Australia is at latitude 33S and in the Southern Hemisphere for various reasons, the UVB is about 10% stronger than in the equivalent latitude in the northern hemisphere so somewhat more effective than in Los Angeles or Damascus. If 5000iu/d is more successful than less in NSW I would be interested in hearing your doctor's explanation of why less is required in Canada which is somewhat north of Los Angeles.

    It would also be helpful if your Government stopped interfering in ways that disadvantaged their population and prevented or deterred them from taking advantage of cheap effective strength D3 from the US discount providers.

  33. murali
    Can sunlight falling on human other than at morning and evening produce vitmine D. I leave in India, kerala state. That is near to equator.
  34. Calculated Ultraviolet Exposure Levels for a Healthy Vitamin D Status You can enter your latitude/longitude in this calculator to work out for you how long you need to be in the sun to make 1000iu Vitamin D3.

    The calculator is a bit on the optimistic side.
    For Northerly latitudes we have to remember this is a heat driven process and wind chill factor may make the process impracticable although theoretically possible.

    Do remember also that to achieve the 125nmol/l (50ng/ml) level at which human milk is a complete vitamin d replete food for human babies and at which human DNA would keep vit d equilibrium if we lived naked outdoor lives takes more like 1000iu/vitamin d3 daily for each 25lbs you weigh.
    It's not surprising human skin, given full body sun exposure and midday summer sun exposure creates 10,000~20,000iu in just a relatively short time.
    Typically at latitude 50N an extra 5000~10,000iu/daily may be required in addition to vit d from food/and urban sunlight.

    An easy rule of thumb guide to whether sunlight is likely to provide adequate UVB for vitamin D3 production is that providing your shadow is SHORTER than you are tall it's possible.

    When shadow LENGTH is DOUBLE your standing height there is too little UVB and too much UVA so it's more likely to process any Vit d near skin surface into suprasterols the body doesn't use.

    In the intervening period, when shadow length is greater than height but not twice your height then you are probably doing more good than harm.

    I think it's also worth pointing out that city or urban atmospheres, living near busy roads or under airport runways may mean the amount of particulates in the atmosphere are blocking UVB to the extent that vitamin D production is reduced. I am not aware of any calculator that will help with this. There are Vitamin D lightmeter devices (at a price) that will tell you the UVB/UVA reaching ground level and this is the only way you can know for sure.

    Also remember UVB acts on the 7 dehydroCHOLESTEROL molecule in your skin.
    So if you take statins these act on the Mevalonate pathway and reduce the production of many other substances apart from just cholesterol.
    If cholesterol production is lowered by statins it's inevitable that 7-Dehydrocholesterol ~ CoQ10 ~ testosterone ~ etc are also lowered. So the amount of 7-Dehydrocholesterol in your skin also comes into the equation.

  35. Dear Andreas,

    Thanks so much for your excellent website. I've recently started lchf and believe this is the answer to many of my problems, chiefly obesity (50 lbs. overweight), high bp, aches and pains of age etc.--76 yrs. old). After only 5 days I've lost some weight, sleep better, feel better, and am VERY hopeful, and NEVER hungry.

    But about vitamin D. For several years I had two dangerous bouts with bronchitis (which three times developed into pneumonia) and would mean sleeping in a chair for two or more weeks. I live in Georgia, USA and don't get much sun in winter. I had begun to think bronchitis/ pneumonia would someday kill me; I got sick so frequently that my dr. left a standing prescription of antibiotic and steroid. That was nearly two years ago. I began taking 5000 units of D3 and have had one case which I stopped immediately with the dr.'s prescriptions. Since then (one year and 1/2) I haven't had to use them. I take 5000 to 10000 a day, when I can remember. The reason I take so much is that I read that 20 minutes of full-skin exposure to summer sun creates 20,000 units; so I don't fear an overdose. Thanks again for you work.

    Blessings, Richard

  36. Anne Dunev, PhD, NP
    As a clinician I have seen 3 cases of kidney stones in female patients on high dose synthetic D supplementation just this year, which concerns me. In Nature, Vitamin D seems to appear with Vitamin A, as in fatty fish and fish oil. Nature never provides any vitamin in isolation, and D is also a hormone, which is associated with mobilization of calcium and is active in the kidneys. It does not make sense that a vital nutrient or hormone is so deficient world-wide and I wonder if serum testing is inadequate for the full picture, given the fact that D is synthesized in the skin, and perhaps that is not reflected in serum levels. Cancer is a recent pandemic in human history and dietary D would not have been more available in earlier times. People have always lacked sun exposure in northern climates. I suspect we don't know all we need to know about Vitamin D in humans.
    Reply: #42
  37. Zepp
    One new thing that they detected resently is what Price cald factor X, and that is K2!

    And it seems to be a reasonable explanation to this, becuse you get it mostly by grass.

    I.E. for humans food that have eaten fresh grass.. now a days our food eats soy!

    So to think about if one take D-3, eat grass feed meat, grass feed pigs, grass fedd hens/eggs!

    Or take K2 to your D-3.. at least if you take high doses.

  38. Kuttin
    Can u please help me i wand sun tablat
    Reply: #39
  39. Birgitta
    I have vitamin D deficiency, 14 nmol/L basically. I'm taking pills-2000 units- every day. Really interesting post!
    I also have skin type between 1 and 2, very pale. I burn in the sun, so that explains the issue I guess.
  40. 1 comment removed
  41. Firose
    You are right....... vitamin A (actual vitamin A not beta carotene) & k2 are part of the equation when it comes to vitamin D. Meaning Vegans should never take high dose supplemental D. Anything above 40 is harmful to vegans if they sustain the levels. Meat is important when you take high dose vitamin D

    Next I did develop kidney stones and insulin resistance. I used to pride myself in keeping my fasting glucose level at 68 every day (by getting rid of the unhealthful accumulation of IMCL). What I noticed when I took high dose to treat my autoimmune is that Firstly, it created insulin resistance by taking my glucose level to 70s then kidney stones started forming. Then it jumped to 80s and 90s.

    I understood Salt in my diet is to be blamed. Sodium causes high influx of calcium into cells causing a rise in intracellular calcium (which is the root cause of kidney stones n insulin resistance[also IMCL]). So tookout salt from diet and increased potassium. Basically fruits, vegetables, meat and nuts. Kidney stones stopped but I do think vitamin d3 is required to bring the balance back. Will let you know if you are interested.

    So there is a certain diet to be followed if you need to raise your D levels.

Leave a reply

Reply to comment #0 by

Older posts