title: Is there an optimal vitamin D status for immunity in athletes and military personnel?
abstract: Vitamin D is mainly obtained through sunlight ultraviolet-B (UVB) exposure of the skin, with a small amount typically coming from the diet.It is now clear that vitamin D has important roles beyond its well-known effects on calcium and bone homeostasis. Immune cells express the vitamin D receptor, including antigen presenting cells, T cells and B cells, and these cells are all capable of synthesizing the biologically active vitamin D metabolite, 1, 25 hydroxy vitamin D.There has been growing interest in the benefits of supplementing vitamin D as studies report vitamin D insufficiency (circulating 25(OH)D < 50 nmol/L) in more than half of all athletes and military personnel tested during the winter, when skin sunlight UVB is negligible. The overwhelming evidence supports avoiding vitamin D deficiency (25(OH)D< 30 nmol/L)to maintain immunity and prevent upper respiratory illness (URI) in athletes and military personnel.Recent evidence supports an optimal circulating 25(OH)D of 75 nmol/L to prevent URI and enhance innate immunity and mucosal immunity and bring about anti-inflammatory actions through the induction of regulatory T cells and the inhibition of pro-inflammatory cytokine production. We provide practical recommendations for how vitamin D sufficiency can be achieved in most individuals by safe sunlight exposure in the summer and daily 1, 000 IU vitamin D3 supplementation in the winter. Studies are required in athletes and military personnel to determine the impact of these recommendations on immunity and URI; and,to demonstrate the purported benefit of achieving 25(OH)D>75 nmol/L.
authors: School of Sport, Exercise and Health Sciences, Loughborough University.
authors: Cheng-Shiun
authors: CS
authors: He
authors: School of Sport, Health and Exercise Sciences, Bangor University, United Kingdom.
authors: Xin Hui
authors: XH
authors: Aw Yong
authors: School of Sport, Health and Exercise Sciences, Bangor University, United Kingdom.
authors: Neil P
authors: NP
authors: Walsh
authors: School of Sport, Exercise and Health Sciences, Loughborough University.
authors: Michael
authors: M
authors: Gleeson
mesh_terms: D056352:Athletes; D006801:Humans; D008889:Military Personnel; D014807:Vitamin D; D014808:Vitamin D Deficiency; D014815:Vitamins
chemical_list: D014815:Vitamins; D014807:Vitamin D
keywords: Cholecalciferol; Ergocalciferol; Exercise; Immune; Infection