Effects of 21-day vitamin D supplementation on sports performance and exercise-induced inflammation: a randomized double-blind trial
TL;DR
Twenty-one days of vitamin D3 supplementation increased serum 25(OH)D concentrations but did not improve anaerobic performance, and Supplementation was associated with changes in selected resting and post-WAnT inflammatory biomarkers, suggesting modulation of the biochemical inflammatory response to repeated supramaximal anaerobic exercise.
Abstract
Objectives While an increasing number of studies highlight the significance of vitamin D supplementation for athletic performance, the effects of short-term high-dose vitamin D3 supplementation on exercise-induced inflammation remain unclear. This study aimed to evaluate the effects of 21 days of vitamin D3 supplementation (10,000 IU/day) on inflammatory biomarkers and maximal anaerobic performance in physically active men performing the 2 × Wingate Anaerobic Test (2xWAnT). Methods Thirty physically active men were randomly assigned in a double-blind manner to a vitamin D3 group (10,000 IU/day in vegetable oil; n = 15; aged 24.21 ± 4.35) or a placebo group (vegetable oil; n = 15; aged 23.15 ± 3.44). During the supplementation period, one participant from the vitamin D3 group and two from the placebo group were excluded because of non-compliance, leaving 27 participants for the final analyses (vitamin D3, n = 14; placebo, n = 13). Venous blood samples were collected at rest, immediately after, 3 h after, and 24 h after the 2xWAnT, before and after the 21-day intervention. Results Resting 25(OH)D increased by +55.7% after supplementation in the vitamin D3 group. Wingate outcomes showed no differential effect of vitamin D3 versus placebo on anaerobic performance. At rest, vitamin D3 supplementation was associated with lower IL-1β and IL-6 concentrations and higher IL-10 concentrations. After the 2xWAnT, the vitamin D3 group showed an attenuated IL-1β response, lower IL-1RA concentrations during the post-exercise period, and higher IL-10 concentrations across the post-exercise period. In contrast, despite the pronounced exercise-induced increase in IL-6, the post-exercise time course of this biomarker did not differ between groups. Conclusions Twenty-one days of vitamin D3 supplementation increased serum 25(OH)D concentrations but did not improve anaerobic performance. Supplementation was associated with changes in selected resting and post-WAnT inflammatory biomarkers, suggesting modulation of the biochemical inflammatory response to repeated supramaximal anaerobic exercise. Functional recovery outcomes were not assessed.