[Vitamin D - A Critical Review of Current Evidence]

While effects of vitamin D on bone metabolism are widely acknowledged, many questions regarding extraskeletal actions of vitamin D have emerged. In-vitro data show the expression of the nuclear vitamin D receptor in a variety of different extraskeletal tissues. However, it's relevance in clinical practice is still unclear. Numerous observational studies suggest that low vitamin D levels might represent a risk factor for several diseases, including cancer, cardiovascular disease and diabetes. Very recently, several randomized controlled trials assessing the effect of vitamin D supplementation on prevention of different diseases have been published with disappointing results. In this review we focus on assessment of vitamin D status, as well as results of currently published randomized controlled trials on vitamin D and disease prevention.