Assessment of vitamin D concentration in non-supplemented professional athletes and healthy adults during the winter months in the UK: implications for skeletal muscle function

Abstract

The current study implemented a two-part design to (1) assess the vitamin D concentration of a large cohort of non-vitamin D supplemented UK-based athletes and 30 age-matched healthy non-athletes and (2) to examine the effects of 5000 IU · day(-1) vitamin D(3) supplementation for 8-weeks on musculoskeletal performance in a placebo controlled trial. Vitamin D concentration was determined as severely deficient if serum 25(OH)D < 12.5 nmol · l(-1), deficient 12.5-30 nmol · l(-1) and inadequate 30-50 nmol · l(-1). We demonstrate that 62% of the athletes (38/61) and 73% of the controls (22/30) exhibited serum total 25(OH)D < 50 nmol · l(-1). Additionally, vitamin D supplementation increased serum total 25(OH)D from baseline (mean ± SD = 29 ± 25 to 103 ± 25 nmol · l(-1), P = 0.0028), whereas the placebo showed no significant change (53 ± 29 to 74 ± 24 nmol · l(-1), P = 0.12). There was a significant increase in 10 m sprint times (P = 0.008) and vertical-jump (P = 0.008) in the vitamin D group whereas the placebo showed no change (P = 0.587 and P = 0.204 respectively). The current data supports previous findings that athletes living at Northerly latitudes (UK = 53° N) exhibit inadequate vitamin D concentrations (<50 nmol · l(-1)). Additionally the data suggests that inadequate vitamin D concentration is detrimental to musculoskeletal performance in athletes. Future studies using larger athletic groups are now warranted.

New strategies in sport nutrition to increase exercise performance

“…[143,144]. In our laboratory, we have reported detrimental effects on muscle function when concentrations are below 30nmol/L [140] with no performance enhancing effects of vitamin D supplements if the starting concentration is around 50nmol/L [145]. In terms of a supplemental dose, the EFSA have recently stated that 4000iU is the maximum dose that should be used which we have also shown to be an effective dose in correcting deficiencies [146].…”

Muscular effects of vitamin D in young athletes and non-athletes and in the elderly

“…124,125 Enhanced performance was moreover observed in the 30-yard dash of college women after 6-minute exposure to UV light. 126 A randomized placebo-controlled study examined the effects of vitamin D3 supplementation on musculoskeletal performance 127 in highly trained male professional soccer players. Approximately 60% of the athletes on supplementation and 70% of the controls exhibited serum levels of vitamin D prior to treatment of 20 ng/ml.…”

The effect of 14 weeks of vitamin D3 supplementation on antimicrobial peptides and proteins in athletes

“…Recently, we demonstrated that vitamin D status influences the resting plasma cathelicidin concentration and salivary SIgA secretion rate in endurance athletes during a winter training period (He et al, 2013 Vitamin D insufficiency has been reported to be common in athletes in the United Kingdom (UK), especially when training in the winter months (Close et al, 2013;He et al, 2013;Morton et al, 2012). Two studies that assessed the vitamin D status of UK-based professional athletes (latitude 53°N) reported that 62% of athletes (38/61) including professional rugby players, soccer players and jockeys had inadequate serum total 25(OH)D concentrations (<50 nmol/L) in the winter months (Close et al, 2013) and 65% of elite soccer players in the English Premier League (13/20) presented with serum total 25(OH)D concentrations <50 nmol/L in December (Morton et al, 2012). In our previous study on a large student cohort of endurance athletes, we also found that 55% of endurance athletes (100/181) had serum total 25(OH)D concentrations <50 nmol/L at the end of the 4-month winter training period (He et al, 2013).…”