Vitamin D Status, Supplementation and Cardiovascular Disease

This review was conducted to assess the dose-response relationship between vitamin D and cardiovascular disease (CVD) outcomes in humans: Prospective cohort studies indicate a multivariable-adjusted non-linear increase in CVD events at levels of circulating 25-hydroxyvitamin D [25(OH)D] of less than 50 nmol/l. However, Mendelian randomization studies do not support these findings. Although meta-analyses of randomized controlled trials (RCTs) do not rule out small beneficial vitamin D effects on surrogate parameters of CVD risk, such as arterial stiffness, at vitamin D doses equivalent to 1,000-5,333 IU daily, other meta-analyses of RCTs show no reduction in CVD events by vitamin D supplementation. Notably, some cohort studies and a recent RCT provide evidence for harmful effects of vitamin D on CVD outcomes at 25(OH)D levels in excess of 100 nmol/l. In conclusion, more studies in individuals with a deficient 25(OH) D level (i.e. <30 nmol/l) are needed, but caution is necessary regarding supplementation with vitamin D doses achieving a 25(OH) D level which exceeds 100 nmol/l.