Are Vitamin D Supplements Effective in Preventing Disease?

Are you one of the millions of people who are taking vitamin D supplements? People take vitamin D supplements to prevent depression, muscle weakness, cancer, heart disease, and who knows what else. And yet, there is a lack of evidence that vitamin D supplements will prevent any of these conditions.

The trend to test for and treat alleged vitamin D deficiencies took off in 2011 with the publication of a book entitled The Vitamin D Solution - A 3-Step Strategy to Cure Our Most Common Health Problems. The suggestion by the book's author that vitamin D levels of 21-29 ng/ml are insufficient for good health were a bit of a shocker, since blood levels of vitamin D of greater than 20 ng/ml are considered normal.  The book and several studies that seemed to support its thesis led to an increase in vitamin D screening blood tests, and to recommendations by many physicians that their patients consider taking vitamin D supplements.

However, the Institute of Medicine says that there is no evidence that people who have vitamin D levels above 20 ng/ml (i.e. normal vitamin D levels) will benefit from taking additional vitamin D.  In addition, two studies published this year show that vitamin D supplements don't prevent heart attacks and don't protect women against cancer. An ambitious 5-year study is now underway to try to determine once and for all whether vitamin D supplements are of any use in preventing cancer, heart disease, and stroke.

I don't know about you, but I'm taking vitamin D deficiency off my list of things to worry about, at least for now.