The hoopla over vitamin D reached a crescendo this year, with article after article and website after website touting this vitamin’s amazing ability to prevent diseases ranging from the common cold to cancer. As a result, many doctors found themselves fielding patient requests for vitamin D testing, while others jumped on the bandwagon and began promoting both testing and supplements to their patients. Not surprisingly, sales of vitamin D supplements quickly reached record levels.

But a new report released this week by the widely respected Institute of Medicine will hopefully cut through the hype.

The IOM is an independent, nonprofit organization that provides unbiased and authoritative advice to decision makers and the public. The IOM was asked by the United States and Canadian governments to review all of the research available on vitamin D and calcium. The report it released was written by a 14-member committee, which reviewed nearly 1000 published studies.

The committee’s findings confirm, yet again, that when it comes to vitamins and supplements, more is not always better. Here’s what they found:

  • There is no evidence to show that it is beneficial to take the very high levels of vitamin D that have been recommended over the past few years.
  • Very high levels of vitamin D could be harmful.
  • Most people get adequate amounts of vitamin D through their diet and sun exposure.
  • Most people do not need calcium supplements. The one group that may not be getting enough calcium is adolescent girls.
  • Older women who take too much calcium are at greater risk of developing kidney stones or heart disease.
  • For bone health, the level of vitamin D in the blood needs to be 20 to 30 nanograms. Most people who have a vitamin D blood test will be in this range.
  • Laboratories can set any level they want to label people “deficient.” The lower the level the more people who will deemed “deficient” and who will be told they should take supplements.
  • Vitamin D may help prevent other health problems, but there is currently not enough evidence to say that it does.

Based on its review of the data, the IOM recommends that people up to age 70 should get no more than 600 IUs of vitamin D a day, and that after age 70 people no more than 800 IUs. The last time the vitamin D recommendations were updated was in 1997. Those recommendations called for children to get 200 IUs a day; adults up to 70 to get 400 IUs;, and people over 70 to get 600 IUs. So, while the IOM is recommending higher doses, they are not recommending doses anywhere near what some doctors, books, and websites have been promoting: 3,000 IUs and higher.

Why should you believe what the IOM says? They did not go into this thinking vitamin D was good or not good. Their intent was to determine whether people were getting adequate amounts of vitamin D, if current recommendations should be changed, and if very high levels of vitamin D were beneficial or potentially harmful. I point this out because reviewing the comments left on news sites about the report it’s clear that many people believe the IOM is influenced by pharmaceutical companies, or Congress, or the milk industry, or is biased in some other way. In reality, the IOM does not benefit in any way by saying there is no evidence that vitamin D is as beneficial as many people have come to believe it is.

Because supplements are widely available, no one can get people to stop taking lots of vitamin D. But before you join the bandwagon (or if you already have) think about this: not that long ago vitamin E was the supplement-of-the-day, with high levels of vitamin E use being widely promoted for an array of health benefits. But we now know that vitamin E didn’t really offer those benefits at all—and that high levels can actually be dangerous.

Repeatedly, we have learned that supplements don’t always do what actual foods do, and that your best bet is to eat a well-balanced diet. You can learn more about which foods are good sources of vitamin D here. So, save the money you’d spend on vitamin D supplements and buy yourself some comfy new shoes to wear for a walk around the block—which really can reduce your risk of disease!

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4 Responses to Vitamin D: IOM Cuts Through the Hype

  1. Gail Payne says:

    The study is BS. Everyone is different and many many people north of Virginia do not get adequate amounts of Vit D from the sun. The blanket statement by the IOM is dangerous. I am going to get off your mailing list. Vit. D is cheap. Meds are expensive and always have bad side affects. I don’t plan on taking megadoses of Vit. D. Doctors need much more training in nutrition and less reliance on drugs in their practices.

  2. T says:

    I follow these stories with interest, but what seems to be missing is the context of assessing one’s Vitamin D level (for all the limitations of available tests), and supplementing accordingly. I’ll never know what mine was prior to my breast cancer diagnosis, but when it was first tested a year after, my vitamin D level was severely deficient.

    I was prescribed mega-doses, and eventually my level neared being within normal range. Once it was “in range”, we tapered down the dosage, tweaking daily supplementation with weekly mega-boosts, and with monitoring, we continue to adjust the amounts accordingly.

    So, it makes sense to determine supplementation according to whatever baseline is already there – I wasn’t taking massive amounts blindly. I was taking them because I was severely deficient – and for no discernible reason (plenty of sun exposure, reasonably healthy diet) and despite the mega-dosages, the levels were slow to rise and never approached toxic levels.

    How Vitamin D relates to cancer risks or prevention is yet to be determined, but it seems obvious that if nothing else, the effort should be to at least strive to ensure an individual’s levels fall within the current guidelines for “normal range” as a starting point.

  3. Spencer Blackman MD says:

    I have to say, I am quite surprised to see this perspective associated with a group dedicated to breast cancer eradication. There is very good initial evidence that low vitamin D levels and mutations to genes coding for the vitamin D receptor may be related to increased risk for a number of cancers, including those of the breast. This connection is not just believed by those on the “bandwagon”, as you put it, but vitamin D researchers and experts who follow the literature intimately, as well as informed clinicians trying to do the right thing for their patients. You also misrepresented the recommendations of the IOM report. In fact, the IOM said the recommended daily minimum needed for bone health is 600 IU for those under age 70, a 300% increase from their previous recommendations, and that daily doses up to 4000 IU are completely safe. The report also states that daily doses up to 10,000 IU daily have not been shown to be associated with any toxicity, but that they could not say with certainty that more that 4000 IU was safe. This is not the same as saying they felt people should get “no more than 600IU” a day. In my practice in San Francisco, at least 30% of patients I test have levels below 20 ng/mL, and over 80% have levels below 30 ng/mL. This is a legitimate epidemic at higher latitudes. While there may be some people truly taking too much vitamin D, the vast majority on supplements are taking under 4000 iu/day, a dose consistent with the IOM report’s very conservative safe dose. Finally, I disagree that the IOM is unbiased. Ignoring the hundreds of high-quality studies suggesting vitamin D has more benefits than just bone health seems like a slanted view to me, and I am still trying to understand how they came to that conclusion. It seems possible to me that the IOM does benefit from refusing to acknowledge this evidence, as admitting to their mistake in not acknowledging it sooner erodes their credibility significantly. But in truth, in the eyes of many vitamin D experts, including those the IOM asked to review their report (and then whose highly critical analyses the IOM has yet to release to the public) this report does just that.

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