Adiposity and the relationship between vitamin D and blood pressure

Objective. Circulating vitamin D (25OHD) concentrations are negatively associated with blood pressure (BP) but little is known about the mechanisms for this relationship. Adiposity is positively associated with BP and inversely with circulating 25OHD concentrations but no studies have assessed the relationship between plasma 25OHD and adiposity on BP. The goal of this study is to investigate if the association between plasma 25OHD and BP is mediated by adiposity. Materials/Methods. The relationship between plasma 25OHD, systolic and diastolic BP, and adiposity [BMI, waist circumference, visceral adipose tissue (VAT)] was assessed in a multi-ethnic cross-sectional study of Aboriginal (n = 151), Chinese (n = 190), European (n = 170), and South Asian (n = 176) participants by linear regression models. Results. Plasma 25OHD concentrations were negatively associated with systolic (standardized B = -0.191, P < 0.001) and diastolic BP (standardized B = -0.196, P < 0.001) in models adjusted for age, sex, ethnicity, family history of CVD, smoking status, alcohol consumption, and physical activity. The negative relationship between plasma 25OHD concentrations and systolic and diastolic BP was attenuated after the addition of BMI, waist circumference, and VAT to the models, but the relationship remained significant. Plasma 25OHD concentrations accounted for 0.7% and 0.8% of the variance in systolic and diastolic BP, respectively. Conclusion. These findings suggest that the relationship between vitamin D and BP is independent of adiposity. Further studies are required to determine the mechanisms by which vitamin D affects BP. (C) 2013 Elsevier Inc. All rights reserved.