Vitamin D deficiency is highly prevalent in North America and worldwide. Measuring 25-hydroxyvitamin D (25-OH D) levels provides the best wat to assess vitamin D nutritional status, as it is the principle storage form of vitamin D. One third to one half otherwise healthy adults have low levels of 25-OH D. The main reasons for the low levels are limited synthesis by the skin due to limited sun exposure or pigmented skin and inadequate dietary intake of vitamin D. Although the role of vitamin D for the musculoskeletal system is well known, there is growing evidence that low levels of vitamin D may adversely affect the cardiovascular system. Vitamin D receptors are distributed in many tissues which includes vascular smooth muscle, endothelium, and cardiomyocytes. Several studies reported an association between lower vitamin D levels and renin activity, blood pressure, coronary artery calcification, and cardiovascular disease. Ecological studies have reported higher rates of heart disease and hypertension the further a population is away from the equator. The phenomenon could partially be explained by the higher prevalence of vitamin D efficiency in areas with less exposure to sunlight. The association between vitamin D status and the incidence of cardiovascular events was investigated prospectively, in a large ambulatory, all white, community-based sample of individuals free of cardiovascular disease at baseline. Vitamin D status was assessed by measuring 25-OH D levels and prespecified thresholds were used to define degrees of deficiency [< 15ng/mL, (37.5 nmol/l), <10 ng/mL (25 nmol/L)]. In this study, vitamin D deficiency was associated with an increased risk of cardiovascular disease. The higher risk was particularly strong among individuals with hypertension, in whom 25-OH D levels < 15 ng/mL were associated with a 2- fold risk of cardiovascular events. The authors conclude “Vitamin D deficiency is associated with incident cardiovascular disease. Further clinical and experimental studies may be warranted to determine whether correction of vitamin D deficiency could contribute to the prevention of cardiovascular disease.”
[Wang TJ, et al. Circulation 2008;117:503-511]