Effect Of Vitamin D At Rest And In Response To Maximal Exercise

Abstract

Conflicting evidence suggests insufficient vitamin D (VitD) levels are associated with high resting blood pressure (BP). However the relationship between VitD and the peak systolic BP (SBP) response to exercise, a predictor of future hypertension, has yet to be investigated. PURPOSE: We sought to examine the relationship among serum 25-hydroxy VitD (25[OH]D), resting BP, and the peak SBP response to a graded exercise stress test among a large sample (n=417) of healthy men (49%) and women (51%) over a broad age range (20-76 yr; mean age 44.1±0.8y). We hypothesized that individuals with clinically sub-optimal VitD would have higher resting BP and a peak SBP response to a graded exercise stress test compared to individuals with optimal VitD levels. METHODS: Fasting serum VitD, anthropometrics, resting BP, and peak exercise SBP were obtained at the baseline visit of a larger clinical trial (STOMP; NCT01140308). RESULTS: Mean VitD levels were 36.1±0.7ng/mL, with 41.2% of individuals classified as sub-optimal (<32ng/mL). Average resting BP was 118.9±0.6/75.3±0.5mmHg, with 41% of individuals having high BP (n=174) consisting of those with pre-hypertension (32.5%) and established hypertension (8.5%). Individuals with optimal VitD had higher resting SBP (120.6±13.4mmHg vs. 116.4±12.7mmHg; p=0.002) and DBP (76.0±9.9mmHg vs. 74.1±9.1mmHg; p=0.048) than individuals with sub-optimal VitD, respectively. Similarly, individuals with optimal VitD tended to have a greater peak exercise SBP response than individuals with sub-optimal VitD (p=0.114). CONCLUSION: In contrast to our hypothesis, VitD was positively associated with resting BP levels, but was not associated with peak SBP under maximal exercise conditions. Additional studies are needed to confirm our findings and to provide insight into mechanisms underlying these associations among individuals with high BP. TRIAL REGISTRATION: NCT01140308