The role of vitamin D in dyslipidemia and cardiovascular disease.

Dyslipidemia and vascular calcification are important predictors of cardiovascular disease (CVD). Vitamin D may have an influence on these two CVD risk markers. We performed a systematic review on vitamin D, dyslipidemia, statins, vascular calcification and CVD. The vast majority of intervention studies did not show an effect of vitamin D on serum cholesterol levels. There is however evidence for a triglyceride-lowering effect of vitamin D which primarily comes from studies with chronic kidney disease patients, a group with elevated triglyceride levels. The previously presumed influence of statins on circulating 25-hydroxyvitamin D levels and on cellular vitamin D actions remains obscure. Experimental studies on vascular calcification and CVD suggest a biphasic effect of vitamin D with harmful effects at both low and high vitamin D levels. Epidemiological studies on vitamin D and vascular calcification are inconsistent at present, but are probably biased by confounding. Prospective cohort studies consistently indicate an enhanced multivariable-adjusted CVD mortality risk when circulating 25-hydroxyvitamin D levels are below 25 nmol/l. Adequately designed randomised controlled trials investigating the dose-response effect of vitamin D on different CVD outcome parameters are now warranted.