Tuesday, September 27, 2016

Vitamin D Impacts Exercise Performance, Cortisol, and Heart Health

Vitamin D Impacts Exercise Performance, Cortisol, and Heart Health
September 27, 2016
Vitamin D supplementation reduces cardiovascular risk factors and cortisol levels and improves exercise performance, according to a randomized, placebo-controlled, single-blind, parallel trial published in August 2016.
In this study, 15 healthy subjects were given 2,000 IU of vitamin D3 daily or a placebo for 14 days. Researchers assessed body composition, systolic blood pressure (SBP), diastolic blood pressure (DBP) and arterial elasticity (as measured by pulse wave velocity, PWV) at baseline, after 1 week, and on day 14 of the study. Cortisol and cortisone levels were measured using two 24-hour urine samples. The study authors evaluated the participants' performances on a bike ergometer and noted the distance cycled in 20 minutes and the Borg Scale rate of perceived exertion (RPE).
After 2 weeks, vitamin D supplementation resulted in a pronounced reduction from baseline in resting SBP (115.8 ± 17.1 to 106.3 ± 10.9 mm Hg) and DBP (75.4 ± 10.3 to 68.5 ± 10.1 mm Hg). Arterial stiffness, urinary free cortisol levels, and the cortisol/cortisone ratio also significantly declined in the vitamin D group. The reduction in cortisol was thought to be due to inhibition of 11 β-hydroxysteroid dehydrogenase type 1 (11β-HSD1), the enzyme responsible for converting cortisone to active cortisol. Exercise-induced increases in SBP and DBP were markedly attenuated by vitamin D supplementation.
Furthermore, subjects taking vitamin D significantly increased their distance cycled in 20 minutes and the Borg Scale RPE declined. Participants taking placebo did not experience any of these beneficial effects.
According to the study authors, "These results suggest that daily vitamin D supplementation may ameliorate CVD risk factors including a decrease in 11β-HSD1 activity, as evidenced by the decrease in the cortisol/cortisone ratio, and improve exercise performance in healthy individuals."
Al-Dujaili EA, et al. Ther Adv Endocrinol Metab. 2016;7:153-65.