The Public Health Implications of the 2010 Dietary Guidelines

An Expert Interview With David L. Katz, MD, MPH

Janet Kim, MPH


February 15, 2011

In This Article

Dietary Supplementation

Medscape: Guidance on dietary supplementation, notably vitamin D, is generally lacking in the new review. Since the 2005 edition of the guidelines, vitamin D has been upgraded to a nutrient of concern for all Americans, no longer limited to specific population groups, such as older adults, people with darker skin, or individuals with insufficient sun exposure. Do you think the recommendations concerning vitamin D and its supplementation should have been stronger?

Dr. Katz: The timing of this is, of course, very interesting because an IOM [Institute of Medicine] committee recently reviewed vitamin D and reached conclusions that most people can get enough vitamin D through a combination of diet and sun exposure and that routine supplementation may not be necessary.[7,8] In fact, I and many others are not entirely enthusiastic about that conclusion. In my clinical experience, I find that many of my patients are vitamin D deficient, need supplements to get anywhere near the middle of the reference range of normal values, and do feel clinically better when their levels are normalized. I think this is a matter of some concern.

On the other hand, these are dietary guidelines, and I don't really mind if they don't spend a lot of time or devote much emphasis to nutrient supplementation. I think supplementation is important in select discussions of diet. If you're going to advocate for a vegan diet, which excludes all animal products, some nutrient deficiencies will reliably and predictably occur, such as vitamin B12. Making allowance for supplementation to avoid nutrient deficiencies that a dietary pattern will predictably cause clearly does make sense.

However, there is cause for the "dietary" guidelines to deal only selectively with the issue of supplements. A dark side to the dietary guidelines encouraging a specific nutrient, as they did this time for vitamin B12, is that the food industry will almost certainly respond with a proliferation of products that will sport a banner ad on the front of the package saying, "fortified with vitamin B12 in accordance with the 2010 dietary guidelines." The problem with that is quite often the claims about nutritional properties, while true, are misleading about the overall nutritional quality of the product. Remember the era when everything contained "essence" of oat bran, with big banners on the front of the pack to announce it?

Potentially the same could hold true, then, with vitamin D, already the nutrient darling du jour. If the dietary guidelines were explicit about the value of fortification, we would be seeing more fortified foods and more marketing messages in conjunction with them.

By and large, I prefer supplementation to be addressed as a separate issue. We have to recognize that no matter how good a tool is -- and we could debate how good the dietary guidelines are as a tool -- it's a tool designed to do just one job: in this case, to guide people toward an overall dietary pattern that's conducive to health. No one tool can do every job, and so the issue with supplementation, which very often is a more clinical issue, is that it needs to be more customized. Bottom line: I was not bothered that vitamin D did not get more emphasis in the dietary guidelines. However, I wasn't completely happy with the conclusion of the IOM committee that reviewed vitamin D because I think they erred on the low side.


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