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Sports Med. 2017 Nov;47(11):2323-2339. doi: 10.1007/s40279-017-0749-4.

Effects of Vitamin D Supplementation on Serum 25-Hydroxyvitamin D Concentrations and Physical Performance in Athletes: A Systematic Review and Meta-analysis of Randomized Controlled Trials.

Author information

1
Department of Surgery, McMaster University, Hamilton, ON, Canada. farrokh@mcmaster.ca.
2
Department of Health, Evidence and Impact, McMaster University, Hamilton, ON, Canada. farrokh@mcmaster.ca.
3
, 39 Charlton Avenue East, Hamilton, ON, L8N 1Y3, Canada. farrokh@mcmaster.ca.
4
University of Western Ontario, London, ON, Canada.
5
Department of Surgery, McMaster University, Hamilton, ON, Canada.
6
Victoria Hospital, Castries, Saint Lucia.
7
Department of Health, Evidence and Impact, McMaster University, Hamilton, ON, Canada.

Abstract

BACKGROUND:

There is currently no systematic review examining the effects of vitamin D supplementation among athletes. A rigorous systematic review and meta-analysis is important to provide a balanced view of current knowledge on the effect of vitamin D on serum 25-hydroxyvitamin D [25(OH)D] concentrations and physical performance.

OBJECTIVES:

This systematic review of randomized controlled trials (RCTs) evaluated the effects of oral vitamin D supplementation on serum 25(OH)D concentrations and physical performance in athletes.

METHODS:

Multiple electronic databases were searched, and study eligibility, methodological quality assessment, and data extraction were completed independently and in duplicate. Studies were stratified by baseline vitamin D sufficiency, season, and latitude. A cut-off of 30 ng/ml (75 nmol/l) of 25(OH)D was used for sufficiency. Absolute mean differences (AMDs) between vitamin D and placebo using random effects analysis, and heterogeneity using Q statistic and I 2 index, were calculated. AMD with 95% confidence interval (CI), p value, and I 2 are reported.

RESULTS:

In total, 13 RCTs (2005-2016) with 532 athletes (vitamin D 311, placebo 221) were eligible. A total of 433 athletes (vitamin D 244, placebo 189) had complete outcome data. Among athletes with baseline values suggesting insufficiency, vitamin D supplementation led to significant increases from 3000 IU (AMD 15.2 ng/ml; 95% CI 10.7-19.7, p < 0.0001, I 2 = 0%) and 5000 IU (AMD 27.8 ng/ml; 95% CI 16.9-38.8, p < 0.0001, I 2 = 78%) per day at >45° latitudes. Both doses led to sufficiency concentrations during winter months. Among athletes with baseline vitamin D suggesting sufficiency, serum 25(OH)D sufficiency was maintained from different doses at both latitudes. Of 13 included trials, only seven measured different physical performances and none demonstrated a significant effect of vitamin D supplementation during 12 weeks of follow-up.

CONCLUSION:

Despite achieving sufficiency in vitamin D concentrations from ≥3000 IU supplementation, physical performance did not significantly improve. Between-study heterogeneity was large, and well-designed RCTs examining the effect of vitamin D supplementation on serum 25(OH)D concentrations, physical performance, and injuries in different sports, latitudes, ethnicities, and vitamin D status are needed.

PMID:
28577257
DOI:
10.1007/s40279-017-0749-4
[Indexed for MEDLINE]

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