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The new vitamin D recommendations; why the controversy?

jalili

Those who follow nutrition may have noticed that the Institute of Medicine has released new recommendations for calcium and vitamin D intake. What makes these newer recommendations interesting is that they reflect the growing interest among nutritionists to make recommendations that are based on preventing disease and optimizing health, rather than the old objective of just preventing nutrient deficiency.

 In these new updates we see that calcium now has an “Recommended Dietary Allowance” value for specific ages, genders and life stages, as opposed to the old recommendations that stated an “adequate intake” recommendation. While this may be a notable development for scientists in the field, it’s not an attention getter for the public since the actual target intakes of calcium haven’t really changed very much.

 The real story here is that vitamin D recommendations have increased, in some cases by 50% depending on your age and gender. While this may sound like a big jump, there are some vitamin D researchers who think it hasn’t been increased nearly enough and are pushing for a much higher jump in recommendations. Why the controversy? Well, the currently recommendations were made based on optimizing bone health, however, vitamin D does other things in the body beyond the well-known role it plays in bone health.

 In the last few years research studies have reported a protective role for vitamin D against various cancers, metabolic syndrome, and heart disease to name a few. These studies led some scientists to recommend a higher RDA for vitamin D. If this is true then why aren’t we raising the vitamin D recommendation even more?

 Well, it’s not as straightforward as you may think. For example, vitamin D has been reported to protect against prostate cancer in some studies, but other studies have found that it actually increases risk of prostate cancer. These seemingly opposite results are due to the fact that there are individual genetic variations in people, dosage differences, and other lifestyle factors (such as sun exposure) that come into play to make the effect of higher dose vitamin D less predictable. 

 Simply put, we (the scientific community) aren’t quite sure which people will benefit from higher vitamin D intake and which may be harmed. Right now those in the “let’s study it more” camp have won the debate over the “increase the recommendations even more” camp. So what we are left with for now are vitamin D recommendations that are based on optimizing bone health. In my opinion, I think that’s OK until we can get a clearer picture of who can benefit from higher vitamin D levels.

  • joan

    Just an anecdote: the technician who did my bone scan a couple of years ago said that there are women like me who do everything right–do weight-bearing exercise, get plenty sunshine, eat dairy, and take calcium–who have crappy bones. Then, a homeless crack addict comes in and has great bones. This is not meant to dissuade people from eating healthily, but when you hear about adverse effects of calcium and Vit D, it does give pause.