Abstract
BACKGROUND: Several observational studies have recently suggested an inverse association of circulating levels of vitamin D with blood pressure. These findings have been based mainly on Caucasian populations; whether this association also exists among Hispanic and African Americans has yet to be definitively determined. This study investigates the association of 25-hydroxyvitamin D (25[OH]D) with blood pressure in Hispanic and African Americans. METHODS: The data source for this study is the Insulin Resistance Atherosclerosis Family Study (IRASFS), which consists of Hispanic- and African-American families from three US recruitment centers (n =1,334). A variance components model was used to analyze the association of plasma 25[OH]D levels with blood pressure. RESULTS: An inverse association was found between 25[OH]D and both systolic (beta for 10 ng/ml difference = -2.05; P < 0.01) and diastolic (beta for 10 ng/ml difference = -1.35; P < 0.001) blood pressure in all populations combined, after adjusting for age, sex, ethnicity, and season of blood draw. Further adjustment for body mass index (BMI) weakened this association (beta for 10 ng/ml difference = -0.94; P = 0.14 and beta for 10 ng/ml difference = -0.64; P = 0.09, respectively). CONCLUSIONS: 25[OH]D levels are significantly inversely associated with blood pressure in Hispanic and African Americans from the IRASFS. However, this association was not significant after adjustment for BMI. Further research is needed to determine the role of BMI in this association. Large, well-designed prospective studies of the effect of vitamin D supplementation on blood pressure may be warranted.