Abstract:
Background: Populations with low vitamin D status, such as blacks living in the US or UK, have increased blood pressure (BP) compared with whites. We analyzed the association between serum 25-hydroxyvitamin D (25OHD) and BP to determine whether low 25OHD explains any of the increased BP in blacks. Methods: The Third US National Health and Nutrition Examination Survey (NHANES III) is a cross-sectional survey representative of the US civilian population during 1988 to 1994. Analyses were restricted to 12,644 people aged 20 years with measurements of BP and 25OHD, after excluding those on hypertensive medication. Results: Adjusted mean serum 25OHD was lowest in non-Hispanic blacks (49 nmol/L), intermediate in Mexican Americans (68 nmol/L), and highest in non-Hispanic whites (79 nmol/L). When participants were divided into 25OHD quintiles, mean (standard error) systolic BP was 3.0 (0.7) mm Hg lower (P .0004) and diastolic BP was 1.6 (0.6) mm Hg lower (P .011) for participants in the highest quintile (25OHD 85.7 nmol/L) compared with the lowest (25OHD 40.4 nmol/L), adjusting for age, sex, ethnicity, and physical activity. Further adjustment for body mass index (BMI) weakened the inverse association between 25OHD and BP, which remained significant for systolic BP (P .05). The inverse association between 25OHD and systolic BP was stronger in participants aged 50 years than younger (P .021). Ethnic differences in 25OHD explained about half of the increased hypertension prevalence in non-Hispanic blacks compared with whites. Conclusions: Vitamin D status, which is amenable to intervention by safely increasing sun exposure or vitamin D supplementation, was associated inversely with BP in a large sample representative of the US population.