Many of our patients have been asking about the recent media reports related to vitamin D that were released at the end of November 2010. The Institute of Medicine’s Food and Nutrition Board (FNB) released a report stating that “most people in the United States and Canada get plenty of vitamin D and calcium and may damage their health by taking too many supplements.” For those of us in the field of health and nutrition this statement came as quite a surprise considering most of the research on vitamin D for the last decade has been so overwhelmingly supportive of increased vitamin D intake and supplementation.
The only way to make sense of the FNB’s recommendations is to consider that they serve to look at nutrition only from a broad population based perspective rather than consider the biochemical individuality of each person. The FNB must balance the risks of taking too much vitamin D against the risk of taking too little. And yes, there is such a thing as getting too much vitamin D! As clinicians we have the advantage of being able to test blood levels of vitamin D. The general consensus is that Vitamin D-25 (OH), the stable storage form of vitamin D in the blood, should be between 40-60 ng/ml for optimal health. Typically our patients require 2000 IU to 5000 IU of vitamin D3 per day to reach and maintain these levels. However this dose may be too much for some people and may explain why the recent dosing recommendations by the FNB are so much lower than what is typically used by physicians.
Regardless, these recent confusing media reports should not make you shy away from your vitamin D supplements especially during these cold, dark winter months. Keeping vitamin D at the optimal level can protect against many cancers, infections, bone loss and mood disorders. I will need more convincing evidence than that provided by the FNB before abandoning vitamin D as an important mainstay in health maintenance and disease prevention