Hypertension and Vitamin D

Abstract

The aim of this research was to apply analytical epidemiology to examine associations between hypertension and vitamin D status (serum 25-hydroxyvitamin D (25OHD)). The first objective was to appraise and synthesize the research evidence on the relationship between hypertension and 25OHD. The follow-up objective was to complete a sequence of studies exploring the association between hypertension and 25OHD in two populations with high hypertension and vitamin D deficiency rates, Finland and China. The results of the meta-analysis were that higher vitamin D levels were associated with lower hypertension rates. In a prospective study from Finland higher 25OHD levels at baseline were found to associate with less hypertension and a lower pulse rate. On follow-up only low pulse rate remained associated with higher 25OHD. A hypertension prevalence rate of 34% was reported from a cross-sectional survey in Macau 2012. Potentially modifiable predictors of hypertension were found to be smoking, obesity and lack of exercise, sunlight exposure and low intake of fish. Only 45% of this population on whom blood was collected were found to have sufficient vitamin D status (≥50 nmol/L). Young highly educated women were at greatest risk of not being sufficient. Higher sun exposure, fish intake and more physical activity and less sitting were associated with higher 25OHD levels. In the older population (≥55 years) higher 25OHD levels significantly predicted having either lower hypertension or lower pulse rates. The evidence from these series of studies indicates a small consistent association between vitamin D sufficiency and reduction in hypertension risk. These results are consistent with recent meta-analyses of observational studies. The unique finding from this study is that there is an age cohort differential with younger Chinese having lower vitamin D status and in a population with increasing hypertension this fact may have public health consequences in the future.