Vitamin D3 supplementation using an oral spray solution resolves deficiency but has no effect on VO2 max in Gaelic footballers: results from a randomised, double-blind, placebo-controlled trial

Abstract

Purpose Vitamin D inadequacy is a global health concern in athletes as well as the general population. Whilst the role of vitamin D in skeletal health is well defined, there remains uncertainty over whether vitamin D supplementation has an added benefit beyond bone health.MethodsThis randomised placebo-controlled trial in healthy male and female Gaelic footballers (n = 42) investigated the effect of vitamin D3 supplementation [3000 IU (75 µg) daily for 12 weeks, via an oral spray solution] on VO2 max which was the primary outcome measure. Secondary outcomes included skeletal muscle and lung function.ResultsSupplementation significantly increased total 25-hydroxyvitamin D concentrations compared to the placebo group (mean ± SD change from baseline, 36.31 ± 32.34 vs. 6.11 ± 23.93 nmol/L, respectively; P = 0.006). At baseline, 50 and 22 % of footballers presented with vitamin D insufficiency (31–49 nmol/L) and deficiency (<30 nmol/L), respectively. Total 25-hydroxyvitamin D concentration did not significantly correlate with any measure of physical performance. Analysis of covariance (ANCOVA) models demonstrated that vitamin D supplementation over 12 weeks had no significant effect on VO2 max (P = 0.375), vertical jump height (P = 0.797), left and right handgrip strength (P = 0.146 and P = 0.266, respectively), forced vital capacity (P = 0.573) or forced expiratory volume at 1 s (P = 0.665), after adjusting for confounders. The high prevalence of vitamin D inadequacy observed in this cohort of collegiate Gaelic footballers supports the need for vitamin D supplementation during wintertime to avoid being at risk of poor bone health.ConclusionsTwelve-week daily supplementation with 3000 IU (75 µg) vitamin D3 successfully resolved deficiency but did not have any significant effect on VO2 max, skeletal muscle or lung function.

Seasonal variation in vitamin D status, bone health and athletic performance in competitive university student athletes: a longitudinal study

“…Furthermore, muscular strength did not change across the seasons and concurs with findings from Close et al (21) . Parallel to this, there was no improvement in physical parameters following supplementation in Irish university Gaelic footballers (29) with a lower mean vitamin D status than our baseline and previous authors at 47·4 and 43·1 nmol/l for their intervention and placebo groups, respectively. Although we did not supplement our cohort with vitamin D, it is still comparative for baseline measurements, specifically as both aforementioned were the only UK-based cohorts to our knowledge in this young adult population.…”

Oral spray wintertime vitamin D3 supplementation has no impact on inflammation in Gaelic footballers

“…The analysis conducted in this study formed part of a double‐blind, randomized, placebo‐controlled trial which took place at the University of Ulster Coleraine between November 2014 and April 2015 (Todd et al., ). All procedures were approved by the University Research Ethics Committee (REC/14/0087), registered at http://www.clinicaltrials.gov (NCT02278172) and conducted in accordance to the declaration of Helsinki.…”

“…Gaelic footballers signed informed consent and attended appointments to obtain fasted blood samples. Physical measures were taken before and after a 12‐week intervention, the detailed methods of which have been reported previously (Todd et al., ).…”

“…Those allocated to VD received an oral spray solution which contained 3000 IU (75 μg) vitamin D 3 per spray and those allocated to PL received an oral spray solution that was identical in appearance, smell and taste but contained no vitamin D. The vitamin D 3 content of the oral spray solution was independently verified using high performance liquid chromatography (Eurofins Product Testing, Cheshire, United Kingdom). Compliance was calculated using the weight of the bottle upon study completion (Todd et al., ). Gaelic footballers were instructed to self‐administer a single spray daily for 12‐weeks, specifically aiming at the buccal membrane to promote absorption.…”

Importance of Vitamin D in Athletes and Exercise; A mini review

“…A relative study examined the association between vitamin D status and maximalintensity exercise performance in junior and collegiate hockey players and showed that if vitamin D status is causally related to maximal-intensity exercise performance in athletes, the effect size is likely small [20]. A study evaluated the Vitamin D supplementation in Gaelic players and showed that there was no significant effect on maximal VO2, skeletal muscle or lung function [42]. …”