Panel Clarifies Advice On Vitamin D Intake

A government-organized panel of doctors goes against recent advice to increase vitamin D intake. Their new study says most Americans get plenty of vitamin D in their regular routine and diet — and supplements can even be harmful. NPR's Guy Raz talks with one of the doctors on the panel that released the report — bone specialist Clifford Rosen.

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ROBERT SIEGEL, host:

There's new guidance today from the Institute of Medicine on use of a popular nutritional supplement: Vitamin D. Vitamin D has been flying off the shelves in the past several years, thanks to doctors' warnings that we are all Vitamin D deficient. Well, now comes news that we are consuming too much Vitamin D, and too much calcium in supplements.

GUY RAZ, host:

If it all sounds confusing to you, it was also a surprising conclusion for Dr. Clifford Rosen. He was on an independent panel of medical researchers that determined the Vitamin D craze has gone a bit too far. And he's with us in the studio now.

Dr. Rosen, first of all, it has been practically an article of faith that most Americans don't have high enough Vitamin D levels in their blood. That's not true, you say?

Dr. CLIFFORD ROSEN (Maine Medical Center Research Institute): We don't think that's true. That certainly was an article of faith, and many of us believed it. I certainly did, coming into the Institute of Medicine committee.

I published studies showing low Vitamin D in Maine women, particularly during the winter months. So I was relatively convinced and was supporting Vitamin D supplementation.

RAZ: Now, some doctors recommend an average of a thousand - up to 3,000 units per day. Your panel recommends 600 units per day, per adult. How did you come to that conclusion?

Dr. ROSEN: Well, we looked at what the dietary intake and this was both Canada and the United States. So this was a joint effort.

RAZ: And this was a panel convened at the request of the U.S. government.

Dr. ROSEN: That's right - and the Canadian government; it should be remembered that this is for North America. So all of us had this consensus that we needed to make recommendations. And what we had recommended was 600 units of Vitamin D, and about a thousand milligrams of calcium. How we got there was by first looking at what dietary intake of Vitamin D and calcium was in this country, and in Canada. And much to our surprise, people are consuming adequate amounts of both calcium and Vitamin D.

RAZ: Because it's added to so much of our food?

Dr. ROSEN: That's exactly right. We were really surprised. I certainly was very surprised by this.

RAZ: These two supplements are often recommended together because of bone health.

Dr. ROSEN: Right, that's correct.

RAZ: Dr. Rosen, I remember an article over the summer in the New York Times, and it was about how most of us are vitamin deficient, that the average person should have about 30 nanograms of Vitamin D for every milliliter of blood. It included recommendations to spend at least five to 10 minutes in the sunshine, without sunscreen, three times a week.

And I must confess, I started to do that almost immediately after reading the article. Those recommendations came from Dr. Michael Holick at Boston University. You're now saying all that is unnecessary. What are the rest of us to make of these different recommendations? I mean, it's very confusing.

Dr. ROSEN: It is confusing. And Michael is a good friend of mine and a colleague, and mentored me in my early stages of my career. And he's done a lot for the Vitamin D field, and he's really brought it to the attention of both bone health experts and also others.

So I would just argue that I think we found that 20 nanograms per ML was very sufficient to maintain skeletal health. And indeed, more is not better. And we found no evidence that Vitamin D had effects on other disease states.

RAZ: Like cancer.

Dr. ROSEN: Like cancer or heart disease or neurological diseases or multiple sclerosis. When we started the report, we had over 30 disorders - from autism all the way to multiple sclerosis - that we were looking at to see if there were associations.

RAZ: Well, what's the downside of taking too much?

Dr. ROSEN: Well, that's what got us a little worried. As we got into the report, we actually saw that when levels of Vitamin D got too excessive, not only was the blood calcium increased, but we started to see a signal that suggested you might be at increased risk for other diseases -including, surprisingly enough, fractures.

RAZ: So don't take 5,000 units of Vitamin D a day; that's your recommendation.

Dr. ROSEN: That's definitely our recommendation.

RAZ: Which is available.

Dr. ROSEN: Yeah, 5,000, sometimes more. And many people are taking them. I practice medicine. I'm a referral for lots of doctors to look at their bones of their patients. And many, many, many people are taking Vitamin D supplements.

RAZ: That's Clifford Rosen. He's a bone specialist at the Maine Medical Center Research Institute, and a member of the panel that set new recommendations for Vitamin D and calcium intakes. Dr. Rosen, thank you so much.

Dr. ROSEN: Thanks, Guy.

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