Optimal vitamin D status attenuates the age-associated increase in systolic blood pressure in white Americans: results from the third National Health and Nutrition Examination Survey.

BACKGROUND

The prevalences of both hypertension and vitamin D insufficiency are high in the United States. Recent clinical trials and animal studies have suggested that vitamin D insufficiency may be associated with elevated blood pressure.

OBJECTIVE

With cross-sectional data, we sought to determine whether vitamin D concentrations were related to systolic blood pressure (SBP) in the third National Health and Nutrition Examination Survey (1988-1992).

DESIGN

Blood pressure was classified with 5 categories from the Joint National Committee 7 with a sixth category added to distinguish participants with normotensive SBP (<110 mm Hg) from those with high-normal SBP (110-119 mm Hg). We used predicted marginals to estimate the conditional means of serum 25 hydroxyvitamin D [25(OH)D] and to test for trend across blood pressure categories. We used linear regression to explore the association between vitamin D, blood pressure, and age.

RESULTS

Lower 25(OH)D concentrations were associated with a higher blood pressure category in whites (P<0.001); however, when controlling for age, the association was no longer significant. Concentrations of 25(OH)D>80 nmol/L decreased the age-related increase in SBP by 20% compared with participants having 25(OH)D concentrations<50 nmol/L (P<0.001). Only 8% of blacks had 25(OH)D concentrations>80 nmol/L.

CONCLUSIONS

SBP is inversely associated with serum vitamin D concentrations in nonhypertensive white persons in the United States. This observation provides a rationale for studies on the potential effects of vitamin D supplementation as a method to reduce SBP in persons at risk of hypertension.