Vitamin D and Blood Pressure Among US Adults: A Cross-sectional Examination by Race/Ethnicity and Gender

Introduction: The cross-sectional association of serum vitamin D levels with blood pressure and hypertension status among a representative sample of U.S. adults was examined. Methods: Participants of the National Health and Nutrition Examination Survey from 2001 to 2010 were included in these analyses. Harmonizing of the vitamin D levels from 2001 to 2006 with vitamin D measurement from 2007 to 2010 was done using regression equations released by the Centers for Disease Control and Prevention. Use of vitamin D supplements was assessed for all participants. Statistical analyses included examination of linear association of vitamin D levels with blood pressure and non-linear cubic splines with hypertension in overall population, by gender, and by race/ethnicity. Results: With every 10 nmol/L higher vitamin D, systolic blood pressure decreased by 0.19 mmHg in this population (p < 0.01). In fully adjusted stratified analyses, this association was present among females (-0.25 mmHg, p < 0.01) and non-Hispanic whites (0.22 mmHg, p < 0.01). After race/ethnic and gender stratification, this association was observed among non-Hispanic white females (0.26 mmHg, p = 0.01), non-Hispanic black females (0.65 mmHg, p = 0.02), and marginally significant among Hispanic males (0.33 mmHg, p = 0.07). Non-parametric assessment with cubic splines show that vitamin D has an inverse association with odds of hypertension up to 100 nmol/L with no apparent benefit at higher levels in overall population, and even lower threshold levels of vitamin D in non-Hispanic blacks (50 nmol/L) and Hispanic Americans (70 nmol/L). Conclusions: Significant race/ethnic and gender differences exist in the association of vitamin D and systolic blood pressure. Odds for hypertension are reduced significantly at higher vitamin D levels, but this benefit plateaus at very high vitamin D levels. (C) 2017 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.