Vitamin D, Immune function and acute respiratory infection among athletes; A Systematic Review

Abstract

A systematic review of observational studies and randomized controlled trials was conducted to examine the association of vitamin D, acute respiratory infection, and immune markers among athletes; and also to determine the effects of vitamin D supplementation on these same variables. Eleven eligible trials were identified through PubMed, Medline, Embase, Cochrane Central Register of Controlled Trials, and Google scholar search. Five observational studies and six randomized controlled trials with 631 subjects. Published studies were few, more studies showing no effect of vitamin D supplementation on the duration, severity, and frequency of respiratory infection occurrence. A few studies showed that vitamin D supplementation increased salivary IgA and cathelicidin secretion rates. Insufficient evidence exists regarding the association and effects of supplementation on serum vitamin D concentration with respiratory infection and immune biomarkers among athletes.