Relationship of vitamin D levels to blood pressure in a biethnic population

Background and aims: Accumulating epidemiological and clinical studies have suggested that vitamin D insufficiency may be associated with hypertension. Blacks tend to have lower vitamin D levels than Whites, but it is unclear whether this difference explains the higher blood pressure (BP) observed in Blacks in a population with healthy lifestyle practices. Methods and results: We examined cross-sectional data in the Adventist Health Study-2 (AHS-2), a cohort of non-smoking, mostly non-drinking men and women following a range of diets from vegan to non-vegetarian. Each participant provided dietary, demographic, lifestyle and medical history data. Measurements of weight, height, waist circumference, percent body fat and blood pressure and fasting blood samples were obtained from a randomly selected non-diabetic sample of 284 Blacks and 284 Whites aged 30-95 years. Multiple regression analyses were used to assess independent relationships between blood pressure and 25(OH)D levels. Levels of 25(OH)D were inversely associated with systolic BP in Whites after control for age, gender, BMI, and use of BP-lowering medications (beta-coefficient -0.23 [95% CI, -0.43, -0.03; p = 0.02]). This relationship was not seen in Blacks (beta-coefficient 0.08 [95% CI, -0.14, 0.30; p = 0.4]). Results were similar when controlling for waist circumference or percentage body fat instead of BMI. No relationship between serum 25(OH)D and diastolic BP was seen. Conclusion: Systolic BP is inversely associated with 25(OH)D levels in Whites but not in Blacks. Vitamin D may not be a major contributor to the White-Black differential in BP. (C) 2012 Elsevier B. V. All rights reserved.