D is for “deceiving”

In case you didn’t hear, a recent study took a crack at vitamin D’s longstanding reputation as an immune builder. It was even published in the prestigious Journal of the American Medical Association (JAMA).

In this study, researchers found that a monthly mega-dose of 100,000 IUs of vitamin D3 offered no protection against upper respiratory tract infections in healthy adults. That’s right. None.

I can’t quite believe anyone would claim that vitamin D doesn’t support immunity during cold and flu season. Especially in light of the extensive research we have on the subject.

But… there you have it.

Obviously, the backlash was swift. And you can go ahead and count me among the detractors–because if you look at the details of this study, its conclusion was more than a little deceiving.

Most notably, participants in this trial tested with sufficient levels of vitamin D3 prior to the study period. So it’s not terribly surprising that this experiment proved pointless. The subjects took megadoses of a vitamin they didn’t even need.

Which means, of course, that these results tell us nothing about the benefits of vitamin D supplementation in the general population. In fact, recent stats reveal vitamin D deficiency rates around roughly 42 percent for American adults.

Believe me when I say that you probably need more vitamin D. A lot more.

Make no mistake about it–a daily dose of D3 is a must if you want to fight off colds and flu this winter. I recommend at least 2,000 to 5,000 IU per day for everyone. And this study doesn’t change that.

“Effect of vitamin D3 supplementation on upper respiratory tract infections in healthy adults: the VIDARIS randomized controlled trial.” JAMA 2012; 308(13): 1,333-1,339