Vitamin D fights off colds, obesity, cancer … really? The newest miracle vitamin.

by James Hubbard, M.D., M.P.H.

OK, I think this vitamin D craze is getting a little out of hand.  Every few days there’s some sort of study indicating it helps something new.  The latest I’ve seen is that eating less of the stuff was associated with fatter teens.  Eat more? You might have fewer colds.

I type “vitamin D” in Google news. Low levels are linked to mental decline, poor bone health, more cancer, and in teens, an increased risk of diabetes, heart disease and hypertension.

Have we found the miracle drug?

Probably not.  Most of these are association studies.  For the past year or two, scientists have been seemingly obsessed with finding vitamin D associations. I’ve explained that this does not prove causation, which more-focused studies must determine.

We have abounding proof that we need vitamin D to prevent rickets and help with bone health, but the others are just speculation.  For instance, what if the people low in vitamin D are that way because they don’t get out in the sun and exercise as much? Lack of exercise could be the real cause.  (I’ve talked about how our body makes vitamin D with the sun’s help.)  Or what if they just doesn’t eat as many vegetables and fish?

I expect we’ll find, in fact, vitamin D does decrease our risk of some, but not all, of the associated diseases.  I think it’s prudent to make sure you get plenty from the sun, diet and supplements, if needed. But I have two predictions over the next two years.

  1. There will be wild Internet and book claims that megadoses (2,000 milligrams or more) of vitamin D are the answer to our health problems.
  2. Some study, or studies, will associate too much vitamin D with increase, rather than decrease, of some disease.

What do you think?  Any predictions?

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20 Responses to “Vitamin D fights off colds, obesity, cancer … really? The newest miracle vitamin.”

  1. Steve Parker, M.D. Says:

    I keep thinking about the old saw: If it sounds too good to be true, it probably is.

    A physician did write a book 2-3 years ago about the wonders of vitamin D. I can’t remember the name.

    Remember when statin drugs (for high cholesterol) were breathlessly touted to prevent demenia, prevent hip fractures, save marriages, etc? I’m not sure if any of that panned out. There were jokes about putting statins in the water supply.


    Steve Parker, M.D.s last blog post..Health on the Net Foundation’s Code of Conduct

  2. FatFighterTV Says:

    Interesting. So, why do you think so many scientists are obsessed with finding vitamin D associations? I’m with you on the #2 prediction – isn’t that the way it always goes? :)

    FatFighterTVs last blog post..Intak water bottle tracks how much you drink (Want one?)

  3. cathy Says:

    Hahaha! Love your predictions – and predict that they will come true! (But I’m still taking my vitamin D supplements – just not 10 at a time.)

    cathys last blog post..A wonderful dairy-free dessert

  4. James Hubbard, M.D., M.P.H. Says:

    So right, Steve.

    Its good medicine but no miracle.

    James Hubbard, M.D., M.P.H.s last blog post..How to Help a Loved One: depression, alcoholism, addiction …

  5. James Hubbard, M.D., M.P.H. Says:


    I’m not sure why the obsession, other than kind of group mentality. They see one study showing an association, so decide to see what else it may be associated with. Not a bad thing at all, but then it all comes out on the news, before studies are done to show whether the association is actually a causation.

    James Hubbard, M.D., M.P.H.s last blog post..How to Help a Loved One: depression, alcoholism, addiction …

  6. James Hubbard, M.D., M.P.H. Says:

    Cathy, I’m with you. I’m making sure I get enough Vitamin D, but not going overboard.

    James Hubbard, M.D., M.P.H.s last blog post..How to Help a Loved One: depression, alcoholism, addiction …

  7. Brian Newsome Says:

    There’s an article on this in the latest Fitness Matters, the magazine for the nonprofit American Council on Exercise. Catchy headline: “Shedding Light on Vitamin D Deficiency “Crisis.” It points out how disproved claims of other vitamins: C and E for cardiovascular disease, Beta-carotene for lung cancer, and selenium for prostate cancer. Sad thing is, people are paying upwards of $200 for Vitamin D tests.

    Brian Newsomes last blog post..No harm, no benefit to early TV watching, study finds

  8. James Hubbard, M.D., M.P.H. Says:

    Thanks Brian

  9. James Hubbard, M.D., M.P.H. Says:


    My prediction #1 came through already. garethm01 commented on my past post on vitamin D about the wonders of 1000-5000 mg of daily vitamin D

  10. Choosing The Right Vitamin Supplement : Vitamin Supplements Blog Says:

    [...] James Hubbard’s My Family Doctor Blog » Blog Archive » Vitamin D … [...]

  11. Sagan Says:

    Hm, maybe its because it’s so difficult to consume adequate amounts of vitamin D through food that we can then tout it as being a miracle drug simply because not enough people are getting enough of it to see any of the effects… hehe.

    Sagans last blog post..Reflections on the Sugar Challenge

  12. Ted Hutchinson Says:

    If you look at this chart you may work out it’s somewhat safer to have a natural vitamin d status above 50ng than below that level.
    Have some interesting videos from the leading Vitamin D scientists setting out the evidence for a NATURAL vitamin D status that allows human breast milk to flow replete with Vitamin D3. We evolved living a naked outdoor life and consequently the natural level of 25(OH)D adopts when we spend a few minutes laying naked in the midday sun is probably better for us than the levels most people currently attain.

    There is a reason human skin makes 10,000iu given 20~30 minutes full body sun exposure and it’s up to those who promote lower levels to provide the science to justify lower levels as safe.

    The more we look the more we find low levels of 25(OH)D associate with less favourable outcomes.

  13. James Hubbard, M.D., M.P.H. Says:

    Maybe so Sagan, it goes round and round.

    James Hubbard, M.D., M.P.H.s last blog post..How to Help a Loved One: depression, alcoholism, addiction …

  14. Margo Honeyman Says:

    No, it’s not a miracle drug, not even a vitamin, but a powerful steroid hormone when converted in the body. Scientists are so keen to get the word out, because we now know that it works as an anti-inflammatory agent, and inflammatory-based diseases are rising sharply since the end of world war II. Many diseases have an inflammatory basis eg type 2 diabetes, metabolic syndrome, atherosclerosis, some cancers, Alzheimer’s disease. Prostate cancer occurs more frequently and earlier in those who had VD, colon cancer more in those with irritable bowel syndrome. We evolved in an environment where we got 5-10,000 IU /day but now are more likely to get 200 IU/day. Our bodies need 5000 IU/day, as we have many cells with Vit D receptors. D deficiency is most likely to occur in the elderly (osteoporosis and falls), dark-skinned people (earlier deaths of heart disease), covering people (fibromyalgia, diabetes). D deficiency is a consequence of civilization and moving away from the equator. The costs to the Health Care system of NOT taking D are going to increase to unsustainable levels. Who is going to pay this price?

  15. Dr. J Says:

    At this point I get 400 mg in my multi and the rest from the Florida sunshine. Not sure what I will do in the future. Thank you Dr. Hubbard!

    Dr. Js last blog post..Dr. J on the Denim Diet

  16. James Hubbard, M.D., M.P.H. Says:

    Dr. J, I couldn’t agree more

    James Hubbard, M.D., M.P.H.s last blog post..How to Help a Loved One: depression, alcoholism, addiction …

  17. DR Says:

    I can’t speak to all of the recent claims about the “magic powers” of Vitamin D, but I do know that Vitamin D has been very helpful in keeping my spirits up during the past two dark and freezing cold Canadian winters.

    No more SAD Canadians – yay Vit. D

    DRs last blog post..Stop Counting Calories

  18. James Hubbard, M.D., M.P.H. Says:

    Good to hear it DR. How much do you take?

    James Hubbard, M.D., M.P.H.s last blog post..How to Help a Loved One: depression, alcoholism, addiction …

  19. mike Says:

    Reading some of the earlier posts on this subject shows how little folk know. Take a look at Just this week two studies came to light, vitmainD showing supression of PSA in prostate cancer patients and at the annual conference of Neurologists a 50% reduction in relapses compared to those not on vitaminD. So now we have a cause and effect demonstrated. This one is not going to go the way of the doo-doo!!

  20. James Hubbard’s My Family Doctor Blog » Blog Archive » AMA Resolution Awards: The most interesting and entertaining from the annual meeting Says:

    [...] They’ll keep watch.  Our publisher, Dr. Hubbard, bucked the trendy D-craze and blogged about the real scoop in [...]

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