Vitamin D is critical for health. Virtually every cell in the body has a vitamin D receptor, which, when bound to vitamin D, can influence the expression of more than 200 genes (1, 2). Vitamin D promotes calcium absorption in the intestine and maintains calcium and phosphate levels in the blood, protecting against osteoporosis, rickets, and bone fracture (3, 4). It also regulates immune function, cell growth, and neuromuscular function (5, 6).
With the many roles that vitamin D plays in the body, deficiency of this fat-soluble vitamin is a real cause for concern. Vitamin D deficiency has been found to increase the risk of heart attack, cancer, diabetes, asthma, and autoimmune disease (7, 8, 9, 10, 11, 12). Our modern indoor lifestyle limits our sun exposure, and we can only get a small amount of vitamin D from diet (13). According to the lower boundary of the U.S. lab range of 30 ng/mL, as many as 70 percent of Americans are considered deficient (14, 15).
It’s great that awareness about vitamin D deficiency is increasing, with more doctors than ever testing vitamin D levels. However, like many nutrients, vitamin D follows a U-shaped curve, meaning that both low levels and very high levels are associated with negative health outcomes (16). Unfortunately, few practitioners are aware of the dangers of vitamin D toxicity, and many just test serum vitamin D once and recommend a daily 5,000 or 10,000 IU supplement to their patients.
In this article, I’ll discuss the risks of over-supplementation, why you should get most of your vitamin D from sunlight, and the reasoning behind my current approach to vitamin D.
Risks of Excess Vitamin D Supplementation
But a large body of evidence in the medical literature strongly suggests that optimal vitamin D levels might be lower than these figures. There is little to no evidence showing benefit to 25(OH)D levels above 50 ng/mL, and increasing evidence to suggest that levels of this magnitude may cause harm. Consequences of vitamin D toxicity include heart attack, stroke, kidney stones, headache, nausea, vomiting, diarrhea, anorexia, weight loss, and low bone density (18).
Furthermore, in most studies, taking vitamin D supplements does not decrease risk of death, cardiovascular disease, or other conditions. Based on an exhaustive review of over 1,000 studies in 2011, the Institute of Medicine recommends a much more conservative range of 20 to 50 ng/mL (19).
Some research on Israeli lifeguards suggests that, contrary to popular belief, vitamin D toxicity from sunlight alone (in the absence of supplementation) is possible (20). That said, it is much more difficult to achieve toxic levels through sun exposure alone. Sunlight is the optimal source of vitamin D, and has numerous benefits above and beyond improving vitamin D status.
Beyond Vitamin D: The Many Benefits of Sunlight
Vitamin D is really just the tip of the iceberg when it comes to the benefits of sunlight. A recent 20-year study following 29,518 subjects found that those individuals avoiding sun exposure were twice as likely to die from all causes (21). While this study did not assess vitamin D levels, findings from other epidemiological studies suggest that this cannot be accounted for by the increase in vitamin D production alone.
Indeed, humans make several important peptide and hormone “photoproducts” when our skin is exposed to the UVB wavelength of sunlight (22). These include:
- β-Endorphin: a natural opiate that induces relaxation and increases pain tolerance (23, 24)
- Calcitonin Gene-Related Peptide: a vasodilator that protects against hypertension, vascular inflammation, and oxidative stress (25)
- Substance P: a neuropeptide that promotes blood flow and regulates the immune system in response to acute stressors (26)
- Adrenocorticotropic Hormone: a polypeptide hormone that controls cortisol release by the adrenal glands, thus regulating the immune system and inflammation (27)
- Melanocyte-Stimulating Hormone: a polypeptide hormone that reduces appetite, increases libido, and is also responsible for increased skin pigmentation (27)
Exposure to the UVA wavelength of sunlight has also been shown to have benefits, including increasing the release of nitric oxide from storage (28). Nitric oxide is a potent cellular signaling molecule that dilates the blood vessels and thus reduces blood pressure (29).
Optimal Vitamin D Range Depends on Many Factors
So how much do you need? At the first annual IHH-UCSF Paleo Symposium in San Francisco this year, nutritional biochemist Dr. Chris Masterjohn summarized evidence suggesting that optimal vitamin D levels may vary from population to population, despite the fact that there is currently only one reference range used for all patients.
Ethnicity is one major consideration. For example, black people have lower 25(OH)D than white people in the U.S., yet they typically have much higher bone mineral density. Furthermore, non-Caucasians have lower 25(OH)D levels than Caucasians, even at their ancestral latitudes (32). From these and other studies, it has been suggested that people with non-white ancestry may be adapted to a lower optimal 25(OH)D level than people with white ancestry.
Another factor that influences toxicity is nutritional status. The fat-soluble vitamins A, D, and K work synergistically, and adequate vitamin A and K may protect against toxic effects of excess vitamin D (33). Sufficient levels of potassium and magnesium have also been suggested to protect against vitamin D toxicity (34). Unfortunately, most people have nutrient deficiencies in these micronutrients in the developed world, making them more susceptible to vitamin D toxicity.
What about optimal vitamin D range from an evolutionary perspective? A study on traditionally living hunter–gatherer populations in East Africa found that the Masai and Hadzabe had average 25(OH)D concentrations of 48 ng/mL and 44 ng/mL, respectively (35). These indigenous populations get a great deal of sun exposure but also have very high intakes of vitamins A and K, suggesting that these levels are probably towards the higher end of the optimal range for most people in the modern world.
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Using Parathyroid Hormone Levels to Individualize Vitamin D Testing
As we saw in the last section, 25(OH)D lab ranges should vary by population, genetics, and nutritional status. In the absence of specific ranges, we need other biological markers that can help to clarify vitamin D status. To find these biological markers, we need to look at how vitamin D is metabolized.
When UVB contacts the skin epidermis, vitamin D is produced from 7-dehydrocholesterol. This vitamin D then travels in the blood to the liver, where it undergoes primary hydroxylation (the addition of a hydroxyl group, consisting of one oxygen and one hydrogen atom) on the 25th carbon atom. The result is 25(OH)D, which is the metabolite most widely used to assess nutritional vitamin D status. This compound circulates in the blood until it undergoes secondary hydroxylation on the first carbon atom in the kidney, resulting in 1,25(OH)2D, the active form of vitamin D (36).
You might be wondering: why don’t we test the active form? While certainly informative, the amount of active vitamin D is not directly reflective of nutritional vitamin D status because the secondary hydroxylation step is tightly regulated by parathyroid hormone (37). When the parathyroid glands sense a drop of blood calcium levels, they secrete parathyroid hormone (PTH). PTH stimulates the formation of active vitamin D, which increases calcium absorption in the small intestine and calcium release from bone in an attempt to restore normal blood calcium levels (38).
With a basic understanding of this pathway, we can use PTH, calcium, and active vitamin D3 as markers to give us a more complete picture of someone’s vitamin D status. In his presentation at IHH-UCSF, Dr. Masterjohn suggested that serum PTH levels above 30 pg/mL may be indicative of biological vitamin D deficiency when 25(OH)D levels are borderline low. Conversely, if 25(OH)D levels are borderline low or even slightly below the laboratory reference range (e.g., 25 to 30 ng/mL), but PTH is less than 30 pg/mL, it is unlikely that the patient is vitamin D deficient, and supplementation is not warranted.
Instead of focusing on the 25(OH)D level itself, what we really want to achieve is maximum suppression of PTH levels for optimal calcium homeostasis and bone health. Beyond this level, more vitamin D is not necessarily better.
Conclusion
Based on my assessment of the literature and my own clinical experience, I believe the functional range for 25(OH)D is around 35 to 60 ng/mL. However, I can’t stress enough that there is significant variation among populations. For those with non-white ancestry, the optimal range may be a bit lower. For those with autoimmune disease, the optimal range might be a bit higher (45 to 60 ng/mL) to maximize the immune-regulating benefits of vitamin D. Here are a few recommendations for optimizing your vitamin D level.
- Don’t supplement blindly.
If your 25(OH)D level is:
- less than 20 ng/mL: you likely need some combination of UV exposure, cod liver oil, and a vitamin D supplement
- 20 to 35 ng/mL: get your PTH tested. If PTH is adequately suppressed (less than 30 pg/mL), supplementing is probably unnecessary.
- 35 to 50 ng/mL: continue your current diet and lifestyle for maintaining adequate vitamin D
- greater than 50 ng/mL: try reducing your vitamin D supplements, and make sure you are getting adequate amounts of the other fat-soluble vitamins to protect against toxicity
- Get retested!
Check your levels after three to four months to see if you have achieved or maintained adequate levels of vitamin D. If not, adjust your diet, lifestyle, or supplements accordingly and check again in another three to four months.
- Get sunlight or UV exposure as your primary form of vitamin D.
Reap the many benefits of sunlight beyond just subcutaneous production of vitamin D, and reduce your chance of achieving toxic levels. Spend about 15 to 30 minutes, or about half the time it takes your skin to turn pink, in direct sunlight. Sunscreens not only block production of vitamin D, but also all of the other beneficial photoproducts produced in the skin in response to UVB. - Mind your micronutrients to protect against toxicity.
Try cod liver oil as a good source of vitamins A and D and high-vitamin butter oil or pastured butter and ghee for vitamin K. Sweet potatoes, bananas, plantains, and avocados all contain significant amounts of potassium. Consider supplementing with magnesium as it is very difficult to get adequate amounts of this micronutrient from food due to soil depletion.
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It is an informational article, but according to me excess of Vitamin D is harmful for the human body as taking D as a dosage can act like we are taking steroids which are harmful of we look for long term.
Good Work!
I’m fairly certain that steroids are a positive. The higher a man’s testosterone level is as he ages, the less likely he is to get a whole plethora of diseases like cardiovascular disease.
Testosterone replacement has a lot of benefits but almost all of those benefits accrue/occur in the highest quartile of Testosterone blood levels. Those who receive testosterone replacement but not enough to put them in the top quartile get few of the benefits.
Did Chris evaluate any new studies when writing this article? Did the evidence change since his last article about Vitamin D? If so, please provide URLs to the new studies.
I have MS and supplement vitamin D but not at the high levels my doctor recommends. Early on I read some scientists Questioning this protocol (maybe Paul Jaminet?) and it rang true with me. I take LDN and magnesium also and have been pretty darn healthy for the last 6 years. I give a lot of credit to the LDN and a gluten free low dairy diet. I have a question though-every time I have tried to supplement with K2 I get a migraine -so I don’t supplement. Can anyone tell me why this happens? I am also homozygous for mthfr.
Hi, I’d get your B12, Zinc, checked also look into being low in stomach acid. If your doctor etc has given you a tablet to suppress your stomach acid this may well be counter productive. Also look at your MCV In your blood results, if it’s high even in range and your B12 n Zinc are low, it’s a good indicator your low in stomach acid (Betaine HCL) reason is stomach acid is needed to absorb these nutrients and more,
I got a migrane as well when supplementing with K2… then I learned the supplement was a high dose and had k1 as well so I switch to 99 mcg of jarrows formula. I don’t get migraines anymore
Hi Chris,
I have to point out that nowhere in this article do you mention that there is a difference between Vit D2 and Vit D3.
The recommendations you have given on toxicity caused by vit D do indeed fit the medically given D2, and if you are taking Vit D2 it is recommended not to take over 1,000 p/day.
However studies have shown that Vit D3 given at doses even up to 30,000iu per day for long periods had only a very few people in the study showing mild signs of possible toxicity, while most showed none at all. Studies have shown that the optimal amount of D3 for most people to be supplementing is 5,000iu per day.
I did not find D3 to be safe. It is my understanding that D3 is the active form and therefore more dangerous. People who are unable to convert active D back into the safer storage form end up with toxic levels. After five years of supplementing with 5,000 IUs of D3 per day i ended up bedridden and with severe neurological damage and severe light sensitivity. During all of this time my D25 levels stayed at around 12. It was not until i was told to also check my D1,25 levels that i found out my total D levels were too high. It took six years of no sunlight and restricted diet for my D1,25 levels to return to normal levels. I have still not recovered entirely from the neuro problems and light sensitivity. Although my D1,25 is now normal, my D25 is low at 9. No matter how much i supplement my D25 level stays low. I have read on line where other people have had this happen. The only way to know if you are one of these people is to have both your D25 and D1,25 levels checked.
I don’t necessarily agree with this article. According to it, I have been toxic for the past 5 years. however despite my “toxic” levels of Vitamin D3, I have enjoyed better sleep, reversal of osteoporosis, better mood and less pain. Metabolic panel normal. I don’t think enough is known about optimal levels is known to say specifically what is toxic. It sure hasn’t held true in my case.
Oh, I forgot to mention that along with Vitamin D3, I also take Life Extension Super K with advanced K2 complex. I found this brand to be the most cost effective way to obtain 200 mcg of MQ7 K-2
Siobhan,
Can I ask what your vitamin D level is? I have osteopenia. I’m very interested in what you said about reversing your osteoporosis.
Siobhan Justin note that one of the problems with vitamin D toxicity studies is that like vitamin A, the level that becomes toxic depends upon the lack of sufficient concentrations of other vitamins and minerals. For example, it is almost impossible to ‘over-dose’ on vitamin A if sufficient vitamin D is present. The reverse also being true but the levels of vitamin K, selenium, magnesium, and others can be a factor.
Never taken a supplement and never intend to.
As for Magnesium my father swore by it and died with symptoms of Magnesium overdose.
If you are supplementing a lot it just means you don’t have the right source to eat the right foods.
Naturally I am not talking about people with moderate to severe metabolic disorders.
I’ve never heard of magnesium overdose. Can you explain? I’ve done a lot of research on it and have literally not seen anything to hint at that possibility. The worst side effect I have seen published is diarrhea.
I’ve had it tested and it came in around 19. My doctor
prescribed a Vit D supplement, but I am allergic to the
lanolin it made from…also allergic to other supplements of
vit D. Due to a drug reaction, I am now very sensitive to exposure to the sun and am also heat reactive. Even five minutes in the sun turns my face, ears and neck beet red and hot, like a fever, and I am forced to stay inside most of the summer (I live along the Gulf Coast). I also have developed histamine sensitivity and taking most supplements cause a similar reaction. Do you have any suggestions for an other natural sources of Vit D? Do you know if the “Mushroom/Vit D” article is truthful or an urban legend? Any information you can provide would be appreciated.
You can get vegan vitamin D3 from lichen now from various companies such as Doctors Best and Nordic Naturals
Vitamin D is essential for the human body in infant stages, but if excess vitamin D is also not good for health
I have found that Vitamin D level suddenly shoots up if I continue supplementation above 2000IU and it is very difficult to determine optimal supplementation level. Also I have found that Sunlight works better than supplementation in reducing my skin and hair infection.
From reading, substance P can be key in pain control especially neuro pain. I’ve had D levels checked, ~ 30 but also have have autoimmune problems. It was done by an endocrinologist. I think it was only checked once, recently, and I’ve never had PTH level measured. Very interesting. I have had to do my own testing of hormone levels in the past because of complaints- and the only md who ran a full panel of thyroid tests was Endo.
Hello Chris,
it would be interesting to hear your opinion about vitamin D and the infection connection (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4160567/).
The topic about vitamin D is very confusing. With these hypothesis out there, I find it difficult to recommend anybody with a chronic disease to supplement vitamin D because according to that hypothesis, this would prevent clearance of infection.
On the other hand sun exposure and even supplementation hs clearly shown benefits in individual cases but also in some of the vitamin D studies.
Altogether I share your view that 50ng/ml (with a optimal range of 40-60ng/ml) might be a good orientation. However, what about if that hypothesis above turns out true?
Chris, great insights as usual. Almost everything has got a U curve and even many “paleophiles” seem to forget about it. Supplements didn’t grow on trees and need a conscious use since they are not real food. Anything aside from real food that is not an evolutionary norm need a special awareness and to consider its shortcomings. We don’t have to follow in the more is better trend, otherwise we behave exactly like people we criticize
There has just been a big case in Denmark where babies where given way to much d-vitamin. The manufacturer had made a mistake en the product (D-vitamin drops) and the babies got about 75 time’s more D-Vitamin. I don’t no how long and the long terms effects but in the short term they had to much Calcium in the blod.
I live in the Netherlands. I was diagnosed with hypothyroidism and vit D was measured at that time as well, it turned out to be 23 nmol/L (9 ng/ml). GP prescribed 400 IE (tablet) and when after 6 mo. the vit D was still only at 28, increased that to 800 IE. After a year, it was still only at 34 (13.6). Now, 6 years later, it is between 60 and 80 (24 – 32).
In short, acc. to US common practice, this is way too low. Whence the differences between EU and US? Who is right?
Vitamin D needs to be taken with fat to be better utilized. There are gel capsules with fat or a liquid (Vital Cell Life) available in The Netherlands.
I read Jeff Bowles The Miraculous results of high Dose vitamin D, and he made sense, the big factor is to make sure you match it with vitamin K2 , vitamin A, and magnesium. Later I also discovered that bones also need lysine of all things, and zinc and copper, besides the usual suspects like boron and glucosamine and gelatin. (I learned that one long ago).
So I tried it for about 6 months, and my arthritis didn’t completely go away, BUT here’s a weird thing, my curled up big toenails and little toenails straightened out! The little ones were always my whole life, the big ones curled wit fungus in the last few years and bent into the flesh. But one friend of Jeff Bowles took a picture of his messed up toenail and 20,000 IU straightened it out. I was on 100,000 IU for 6 moths, and it straightened the worse on completely out and the other one straightened but still retains yellow coloring.
Some of us live in places where it’s cloudy 300+ a year. So supplements it is.
I’ve been taking 4000 IU daily for 3 years and my level won’t budge–stuck around 35 ng/mL. I hesitate to take more than that for some reason.
If you are taking D3, it has been my experience and my endo’s as well that you have to take 5000 to make any difference at all. He was right if I am any measure of his success. My levels didn’t change until I increased from 4000 to 5000.
Hi. Where do you live? Did you take vit D3+K2?it is important..I could see on my own skin…last year I had a 23 vit d3 value.. After 2 months of 5000iu vitd3(+100mcg k2)/daily..it went over 55..now I am deficient again.. To 30..but it is my fault for not supplementing..I will start today.
I’m in Seattle. I actually just started supplementing with K2, so I will give it a few months and test again. Thanks!
I get my vitamin d level checked every three months. It had dropped to 9 probably due to little sun exposure and few vitamin d rich foods. I take a liquid supplement from my naturopath. My levels have maintained between 35 and 40 since but we recheck it quarterly to ensure it does not get too high. I really enjoyed your article and gained a great deal of useful information. Thank you!
I had surgery for hyperparathyroidism that removed 2 1/2 parathyroid glands. My parathyroid levels always test low now. I take 1300 mg of calcium citrate and 4,000 IU of vitamin D. Can’t take K2 as I’m allergic to yeast.
Not sure how to have my levels tested to compare to my PTH levels
I thought sun exposure without sunscreen is dangerous. The same way too much vitamin D can cause all sorts of issues, having exposure to uv rays can also cause all sorts of problems. Now I am confused. i also heard, there is no such thing as taking too much vitamin d. Even if that is not true, more sunlight exposure, sure sounds more dangerous to me. I would appreciate a response. ty
Some people now think that it’s suddenly exposing skin that doesn’t have any vit D in it (after winter say) that causes sun damage. Cells in skin have the ability to protect their mitochondria naturally and using sun screens stops this happening. In any normal case how could sun be dangerous? We lived with it for billions of years before we learnt to live in houses.
Never in almost 60 years have I ever used sunscreen. Primates have been evolving for millions of years and they weren’t living in caves 7×24. In fact, humans have shed their “fur coats” to become almost hairless so if sun exposure was a problem, we would have evolved adaptations – which we have; we need the sun for good health.
It’s the sunscreen with the nanoparticles and metal dust that I would be most worried about.
A talk regarding the quality of Vitamin D3 supplements on the market is required because I almost died from taking a incorrectly labelled 2200iu Vitamin D3 supplement by Solgar(parent company is NBTY, Inc.).
http://www.ncbi.nlm.nih.gov/pubmed/20515399
http://www.ncbi.nlm.nih.gov/pubmed/17634473
http://www.ncbi.nlm.nih.gov/pubmed/24298009