Vitamin D: a cardioprotective agent?

Vitamin D is a fat-soluble vitamin that is naturally found in very few foods, is added to others, and is available as a dietary supplement. It is produced endogenously when ultraviolet light strikes the skin. Recent epidemiologic and experimental evidence has suggested that low vitamin D levels may play a role in various cardiovascular conditions, including coronary artery disease, congestive heart failure, valvular calcification, stroke, hypertension, and cognitive decline. Low vitamin D may lead to vascular smooth muscle cell proliferation, endothelial cell dysfunction, vascular and myocardial cell calcification, and increased inflammation. However, the data supporting a cardioprotective effect of vitamin D supplementation are very weak, and the large, controlled clinical trials now in progress should resolve this issue.