Circulating 25-hydroxyvitamin D levels in relation to blood pressure parameters and hypertension in the Shanghai Women's and Men's Health Studies

Little is known about the association of circulating 25-hydroxyvitamin D (25(OH) D) and blood pressure (BP) parameters, including systolic and diastolic BP, pulse pressure (PP), mean arterial pressure (MAP) and hypertension in non-Western populations that have not yet been exposed to foods fortified with vitamins and seldom use vitamin D supplements. A cross-sectional analysis of plasma 25(OH) D levels in association with BP measures was performed for 1460 participants (1055 women and 405 men, aged 40-74 years) of two large cohort studies in Shanghai. Multivariable linear and logistic regressions were conducted. Overall, the prevalence of vitamin D deficiency was 55.8% using National Health and Nutrition Examination Survey, USA criteria and 29.9% using WHO criteria. The median plasma 25(OH)D level in the population was 38.0 nmol/l for men and 33.6 nmol/l for women (P<0.01) among participants who were not on antihypertensive drugs. Among men, BP parameters (systolic BP, diastolic BP and MAP) were significantly and inversely associated with higher quintiles of 25(OH)D compared with the lowest quintile (P-trend < 0.05 for all). Vitamin D non-deficient status (WHO criteria) was inversely associated with hypertension (ORadjusted = 0.29; 95% CI 0.10, 0.82). An inverse association was also found between hypertension and the highest quintile of 25(OH)D (ORadjusted = 0.16; 95% CI 0.04, 0.65 for >= 50.6 nmol/l; Ptrend 0.02). Among women, no significant associations were found for BP parameters and hypertension. The present study shows that vitamin D deficiency is common among adults in urban China. Circulating 25(OH)D levels were inversely related to the levels of individual BP parameters and hypertension among middle-aged and elderly men but not among women. More research is needed to investigate the potential sex differential associations.