Doctor's Note

This is the fourth video in a nine-part series on vitamin D. Be sure to check out yesterday’s video: Is Vitamin D the New Vitamin E?.

Also, check out my associated blog posts for additional context: Eating To Extend Our LifespanVitamin D: Shedding some light on the new recommendations; and Vitamin D from Mushrooms, Sun, or Supplements? 

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  • Michael Greger M.D.

    Please feel free to post any ask-the-doctor type questions here in the comments section and I’d be happy to try to answer them. This is the fourth video in a nine day series on vitamin D. Be sure to check out yesterday’s video-of-the-day Is vitamin D the new vitamin E?.

  • jms

    Are the mortality factors that increase with higher Vitamin D levels related to sun exposure, e.g. skin cancer? If so, I wonder whether higher levels obtained via supplementation would imply the same risk.

    Also, considering the increased risk of mortality from higher Vitamin D levels, how did the Institute of Medicine derive an upper daily limit of 4000 I.U. per day?

    • DrDons

      Hi JMS, The studies track all case mortality and some focus further on deaths due to CV disease and cancer the latter would include skin cancer but they make up only a small number. The recommendations that come out of “expert committees” based on “consensus” have been shown to be highly variable and not very good even when not influenced by industrial/pharmaceutical ties so they have to be viewed as one piece of information. You don’t have to worry about the upper limit if you don’t take supplements. Dr. Gregers Dec 9 video does a great job at demonstrating how complex this issue is. You might enjoy reading John McDougall’s article in his March 2011 Newsletter available on his website entitled, Vitamin D:Values for Normal are Exaggerated. As shown in a study mentioned by Dr. Greger even life guards don’t often meet the recommended levels. So I don’t recommend Vit D supplements except in cases where patients can’t get sun light or have repeat values below 20 after attempts to increase by sun exposure. The other thought is that I wouldn’t be surprised if some day we discover other chemicals that are released by our skin when exposed to sun light… a good reason to stay tuned to for the latest science. It is clear at this point that sun light exposure on a regular basis is important to our health.

  • 2RHealth

    In reading the details in the article you referenced on the U-shaped curve, I was interested to see those in the 90th percentile had a vitamin D level of >37ng/mL and the lowest 10 percent were <18ng/mL. Neither of these groups had much different dietary intake or supplementation than others in the study. Looks like much of the difference is genetic! The only variable that appeared different is a slightly higher percentage of the 90th percentile group had blood samples taken in the June-November time period, although they did not find this a significant confounding variable. Conclusion – some of us may have high vitamin D, even without supplementation! Should we get tested to make sure we don't overdose?

  • DrDons

    Hi 2RHealth, I don’t think you are in danger without taking supplementation. Dr.Gregers series of videos does justice to demonstrating how complex this issue is and how much variability there is within a population. It is good that the institute of medicine is looking at a variety of ways to help sort this out such as using the pharmacokinetics: although we have no good way to measure storage. It is a very complex area with concerns about recommending isolated nutrients see and involving a fat soluble vitamin which can lead to toxicity. Throwing around terms like “optimal” levels is misleading for many reasons when dealing with complex systems. In my opinion when making recommendations that potentially effect 40 per cent of the population I believe caution is in order. For me as a physician patients should be encouraged to get regular sun exposure which varies according to latitude see and for me I would accept Vit D levels are in the 20 -30 range. For patients with minimal sun exposure Dr. Gregers recommendation of 2000/day is reasonable.

  • Michael Greger M.D.

    For some context, please check out my associated blog post Vitamin D: Shedding Some Light on the New Recommendations!

  • David Hollenberg

     In a recent paper “Vitamin D an Pancreatic Cancer Risk – No U-Shaped Curve”,
    the authors say that the U-shaped curve is most likely a statistical artifact and
    that there is no U-shaped curve to be explained.  See .

  • Kartoffelmao

    2000IU or 50mcg every day is just enough to get in the range around 30ng/ml or 80nmol/l levels longterm. This is what study after study shows us.

  • Amanda

    My vitamin D was 18.9 and the range goes from 30.0-100.0 ng/mL
    So seriously deficient… I live in Belgium, we don’t get much sun. So I supplement. Everyone is deficient here

  • Swan

    I use an approved S.A.D. light every day. I used it to cure insomnia and continue to use it to maintain a normal sleep pattern. It is highly effective. I’m extremely sensitive to the sun–bad burns and sun rash, so laying out in it was not an option. Disturbed sleep patterns run in my mother’s side of the family, we haven’t been able to find an explanation.

    Do you think my body can make vitamin D from exposure to this light?

    I am 60, have the bone density of a 20 year old. Walk and swim long distances, but very off and on–6 months can go by when I get no real exercise, although people my age claim I “move too fast” :))

    I consume extraordinary amounts of milk, yogourt, cheese and cottage cheese to get protein. Litres and Litres a week. I eat a very small amount of meat and lots of vegetables and nuts.

    I am female. 5’6″ tall and weigh 120 lbs. My blood pressure is 100/85.

    I am concerned because I am VERY ‘small boned.’

    I chain smoked for 25 years but quit 15 years ago. I would have thought that might have had a serious impact.

    So far no health problems of any description, but I shouldn’t like to be surprised any time soon.

    I tried to be vegan in my 20’s but gained 45 lbs. in less than a year.

    When I am not vegan my weight is constantly stable at 120-125lbs.

    I’ve avoided processed food for the duration of my Adult life and was not

    permitted to eat junk food as a child. My father was an off and on vegetarian.

    People keep telling me my bones are about to turn to chalk. I don’t know what to say to them. When I ask why they think so they cite studies like these.

    I should add that I’m Canadian and milk produced in Canada cannot contain growth hormones, anti-biotics etc. by law and the diary industry if extremely well regulated. Otherwise I’d never consider ingesting it. There is no regulation, however, against feeding the cows corn, or genetically modified feed. I invariably choose 2% milk products.

    There are actually 4 questions here:

    1) Am I making vitamin D from the 10,000 Lux light.

    2) Are the milk products without the toxins a good source of calcium, given that I’m also eating lots of vegetables and nuts?

    3) Do people with different constitutions have different needs?

    4) Is this a ‘time bomb’ situation?

    There are many things I eat because I crave them. Nuts are one example, avocado and asparagus are two others.

    Apologies that this is somewhat off topic, I feel there are so many factors involved in the calcium dilemma, it felt accurate to write this way.

  • tomblakeslee

    Yes, there is a U-shaped curve because vitamin K2 is needed to control whether calcium goes to bones or arteries and other undesirable places. More vitamin D requires more K2 to control it. Most people have a deficiency in K2 and the symptom is CHD and osteoporosis.

    Before refrigeration, our diets were rich in K2 because of fermented foods and fatty meats, Recent dietary advice against consumption of saturated fat and eggs has caused many people to stop consuming the richest food sources of K2. K2 deficiency is common today and causes calcium to be deposited into arteries instead of bones. K2 interacts strongly with Vitamin D and must be increased when vitamin D is increased to prevent these bad side effects.

    The best sources of vitamin K2 are fermented foods such as kefir, cheeses and sauerkraut. It is also found in grass-fed egg yolks and fatty meats. Unfortunately nutrition data is hard to find because vitamin K1 is lumped with K2 even though they have totally different functions. (K1 is blood clotting)

    The Rotterdam study found a 43% relative risk of CHD mortality for upper K2 tertiles but K1 had no significant interaction.

    Misguided dietary advice based on the lipid hypothesis has caused people to avoid most K2-rich foods.

    Dr. Kate Rheaume-Bleue just published an excellent book “Vitamin K2 and the Calcium Paradox”

    • tomblakeslee

      I should clarify. There is a U shaped curve without K2 supplementation but very large doses of D are OK if you also take K2 supplements. You can buy tablets that combine D with K2 .
      Mouse experiments have shown that arterial calcification can be reduced in that way. Dr Kate’s book discusses this.

  • sofia

    I m in saudia living in a flat with no exposure to sun for 6 days n one day only at weekend for outing .so is this enough.

  • Ilana125

    I know you recommend 2,000 mg/day, but what’s the max safe level I could take?

  • Wedi yatok

    This one study Dr. Greger cites produced a u-shaped curve and the suggestion that the optimal serum D level is 30ng/ml. Other studies indicate the risk of various cancers, type 1 diabetes, fractures, MS, etc. are reduced when serum levels are higher, in the 40-60ng/ml range. Note the chart at Reduction of such conditions would imply a tendency toward reduction in all-cause mortality. So either (1) the U-curve study’s findings are flawed (all-cause mortality does not actually increase when serum D levels climb into the 40-60ng/ml range), or (2) at least some of the other studies’ findings are flawed (the higher serum levels don’t actually correspond with reduction in certain specific diseases), or (3) both are accurate, but high D levels are causing some other fatal condition. It is a complex issue, but at least for now I’m keeping my serum levels a good bit higher than 30!

  • Matt

    Hi I’ve been taking Vitamin D as of doctors recommendations but now I’m getting bone pain, back and sides? Is this a toxicity symptom?

  • Omar Gro

    Dr Greger I am disapointed of you… Some of your video are quite misleading this one for example will do more bad than good. It will probably scare people from taking the sun or supplementing with vitamin D. In the us as much as 75% of the people older than 18 are vitamin D defficient promoting cancer. And now you post this video about a study made in Uppsala Sweden with just 1000 males. I dated a swedish girl from that town and I can tell you the salted fish intake is quite high so there might be other factors affecting vitamin D levels and mortality rate. It is nt clear if they checked for this confounding factors in such small population. But I also agree with the motion that everything in excess is bad even vitamins even antioxidants

    • R. Glassberg, D.V.M.

      Could it be that Swedish people take cod liver oil to get vitamin d? Perhaps the U shaped curve is because people with high 25D taking cod liver oil are toxic from Vitamin A over dose.

  • Shmulik Cohen

    According to the articles cited in this video, one have to take a daily amount of vitamin D3 so that his blood will contain the optimal concentration of 30 ng / liter of 25OHD.
    According to my calculations based on the data from the NIH (…/VitaminD-HealthProfessional/) you should take a daily amount of 3,000 IU … That is about 7.5 drops of vitamin D from a 400 IU vial …. Is that so? See in the above mention link the following quote:

    “The FNB committee cited research which found that vitamin D intakes of 5,000 IU/day achieved serum 25(OH)D concentrations between 100–150 nmol/L (40–60 ng/mL), but no greate”

    Your inspirations are welcome….

  • Morrissey

    It would be helpful if you could do a video on how Vitamin K works with
    Vitamin D, as well as what type of K is best. Vitamin K purportedly
    keeps calcium from accruing in one’s arteries, something that’s more
    likely to happen with higher levels of D. This might explain why
    higher very high levels of D might shorten longevity (if not accompanied
    with K.) Thanks.