Circulating 25-Hydroxy-Vitamin D and Risk of Cardiovascular Disease: A Meta-Analysis of Prospective Studies

Abstract

Background—: Vitamin D status has been linked to the risk of cardiovascular disease (CVD). However, the optimal 25-hydroxy-vitamin D (25[OH]-vitamin D) levels for potential cardiovascular health benefits remain unclear. Methods and Results—: We searched MEDLINE and EMBASE from 1966 through February 2012 for prospective studies that assessed the association of 25(OH)-vitamin D concentrations with CVD risk. A total of 24 articles met our inclusion criteria, from which 19 independent studies with 6123 CVD cases in 65 994 participants were included for a meta-analysis. In a comparison of the lowest with the highest 25(OH)-vitamin D categories, the pooled relative risk was 1.52 (95% confidence interval, 1.30–1.77) for total CVD, 1.42 (95% confidence interval, 1.19–1.71) for CVD mortality, 1.38 (95% confidence interval, 1.21–1.57) for coronary heart disease, and 1.64 (95% confidence interval, 1.27–2.10) for stroke. These associations remained strong and significant when analyses were limited to studies that excluded participants with baseline CVD and were better controlled for season and confounding. We used a fractional polynomial spline regression analysis to assess the linearity of dose–response association between continuous 25(OH)-vitamin D and CVD risk. The CVD risk increased monotonically across decreasing 25(OH)-vitamin D below ≈60 nmol/L, with a relative risk of 1.03 (95% confidence interval, 1.00–1.06) per 25-nmol/L decrement in 25(OH)-vitamin D. Conclusions—: This meta-analysis demonstrated a generally linear, inverse association between circulating 25(OH)-vitamin D ranging from 20 to 60 nmol/L and risk of CVD. Further research is needed to clarify the association of 25(OH)-vitamin D higher than 60 nmol/L with CVD risk and assess causality of the observed associations.