Vitamin D status and cardiovascular outcome.

Calcitriol or 1,25(OH)2D, the active hormone, binds to the specific nuclear receptor VDR, which is expressed in rat and human heart and vasculature and has effects on myocardiocytes, smooth cells, and endothelial cells. 25-Hydroxy-vitamin D (25OHD) represents the biomarker of vitamin D levels and reflects vitamin D status. There is consistent evidence that low serum 25OHD levels are associated with increased risk of cardiovascular diseases, including hypertension, coronary artery disease, ischemic heart disease, heart failure, stroke, and type 2 diabetes. Randomized-controlled trials and Mendelian randomization studies so far have not succeeded in proving a benefit of vitamin D supplementation. However, the latter investigations are affected by some methodological limitations, and therefore, it is still unclear if vitamin D deficiency has a causative role in cardiovascular diseases or is rather a marker of poor health in chronic disease.