The purpose of this 6-month randomized, placebo-controlled trial was to determine the effect of season-long (September–March) vitamin D supplementation on changes in vitamin D status, which is measured as 25(OH) D, body composition, inflammation, and frequency of illness and injury. Forty-five male and female athletes were randomized to 4,000 IU vitamin D (n = 23) or placebo (n = 22). Bone turnover markers (NTx and BSAP), 25(OH)D, and inflammatory cytokines (TNF-alpha, IL-6, and IL1-β) were measured at baseline, midpoint, and endpoint. Body composition was assessed by DXA and injury and illness data were collected. All athletes had sufficient 25(OH)D (> 32 ng/ml) at baseline (mean: 57 ng/ml). At midpoint and endpoint, 13% and 16% of the total sample had 25(OH)D < 32 ng/ml, respectively. 25(OH)D was not positively correlated with bone mineral density (BMD) in the total body, proximal dual femur, or lumbar spine. In men, total body (p = .04) and trunk (p = .04) mineral-free lean mass (MFL) were positively correlated with 25(OH)D. In women, right femoral neck BMD (p = .02) was positively correlated with 25(OH)D. 25(OH)D did not correlate with changes in bone turnover markers or inflammatory cytokines. Illness (n = 1) and injury (n = 13) were not related to 25(OH)D; however, 77% of injuries coincided with decreases in 25(OH)D. Our data suggests that 4,000 IU vitamin D supplementation is an inexpensive intervention that effectively increased 25(OH)D, which was positively correlated to bone measures in the proximal dual femur and MFL. Future studies with larger sample sizes and improved supplement compliance are needed to expand our understanding of the effects of vitamin D supplementation in athletes.
Regina M. Lewis, Maja Redzic, and D. Travis Thomas
Kelly Pritchett, Robert C. Pritchett, Lauren Stark, Elizabeth Broad, and Melissa LaCroix
or those participating in sports that require uniforms that minimize skin exposure ( Constantini et al., 2010 ). Given the strong evidence suggesting that vitamin D levels may be lower for certain sports during the winter months, recent research has examined the effects of vitamin D supplementation
Leslie N. Silk, David A. Greene, and Michael K. Baker
Research examining the preventative effects of calcium and vitamin D supplementation has focused on children and females, leaving the effects on male bone mineral density (BMD) largely unexplored. Thus, the aim of this systematic review and meta-analysis is to examine the efficacy of calcium supplementation, with or without vitamin D for improving BMD in healthy males. Medline, EMBASE, SPORTDiscus, Academic Search Complete, CINHAHL Plus and PubMed databases were searched for studies including healthy males which provided participants calcium supplementation with or without vitamin D and used changes to BMD as the primary outcome measure. Between trial standardized mean differences of percentage change from baseline in BMD of femoral neck, lumbar spine, total body and total hip sites were calculated. Nine studies were included in the systematic review with six references totaling 867 participants contributing to the meta-analysis. Significant pooled effects size (ES) for comparison between supplementation and control groups were found at all sites included in the meta-analysis. The largest effect was found in total body (ES = 0.644; 95% CI = 0.406–0.883; p < .001), followed by total hip (ES = 0.483, 95% CI= 0.255–0.711, p < .001), femoral neck (ES = 0.402, 95% CI = 0.233–0.570, p = .000) and lumbar spine (ES = 0.306, 95% CI = 0.173–0.440, p < .001). Limited evidence appears to support the use of calcium and vitamin D supplementation for improving BMD in older males. There is a need for high quality randomized controlled trials, especially in younger and middle-aged male cohorts and athletic populations to determine whether supplementation provides a preventative benefit.
Hyun Chul Jung, Myong Won Seo, Sukho Lee, Sung Woo Jung, and Jong Kook Song
and function ( Barker et al., 2013 ), increased rates of stress fractures ( Ruohola et al., 2006 ), and even poor athletic performance ( Koundourakis et al., 2014 ). Vitamin D supplementation has been proposed for facilitating the number of processes that are important for optimal physical performance
Gal Dubnov-Raz, Netachen Livne, Raanan Raz, Avner H. Cohen, and Naama W. Constantini
It is hypothesized that vitamin D insufficiency in athletes might negatively affect sport performance. The objective of this study was to examine the effect of vitamin D3 supplementation on physical performance of adolescent swimmers with vitamin D insufficiency. Fifty-three adolescent competitive swimmers with vitamin D insufficiency (serum 25-hydroxyvitamin-D concentrations (25(OH)D)<30ng/ml, mean 24.2 ± 4.8ng/ml) were randomized to receive 2,000IU/day of vitamin D3 or placebo for 12 weeks. Swimming performance at several speeds, arm-grip strength, and one-legged balance, were measured before and after supplementation. The age-adjusted changes in performance variables during the study were compared between groups. 25(OH) D concentrations at study end were significantly higher in the vitamin group compared with the placebo group (29.6 ± 6.5ng/ml vs. 20.3 ± 4.2ng/ml, p < .001), yet only 48% of the vitamin group became vitamin D sufficient with this dosing. No between-group differences were found in the changes of the performance variables tested. No significant differences in performance were found between participants that became vitamin D sufficient, and those who did not. No significant correlation was found between the change in serum 25(OH)D and ageadjusted balance, strength or swimming performance at study end. Vitamin D3 supplementation that raised serum 25(OH)D concentrations by a mean of 9.3ng/ml above placebo in adolescent swimmers with vitamin D insufficiency, did not improve physical performance more than placebo.
Gal Dubnov-Raz, Harri Hemilä, Avner H. Cohen, Barak Rinat, Lauryn Choleva, and Naama W. Constantini
Observational studies identified associations between vitamin D insufficiency (serum 25(OH)D > 30ng·ml−1) and risk of upper respiratory infection (URI). Swimmers are highly prone to URIs, which might hinder their performance. The aim of this study was to examine if vitamin D3 supplementation reduces URI burden in vitamin D-insufficient swimmers. Fifty-five competitive adolescent swimmers with vitamin D insufficiency were randomized to receive vitamin D3 (2,000IU·d4) or placebo for 12 winter weeks. A URI symptom questionnaire was completed weekly. Serum 25(OH)D concentrations were measured by radio-immunoassay before and after supplementation. We used linear regression to examine the relation between the change in 25(OH)D concentrations during the trial, and the duration and severity of URIs. There were no between-group differences in the frequency, severity, or duration of URIs. Exploratory analyses revealed that in the placebo group only, the change in 25(OH)D concentrations during the trial was highly associated with the duration of URIs (r = −0.90,p > .001), and moderately associated with the severity of URIs (r = −0.65,p = .043). The between-group differences for duration were highly significant. Vitamin D3 supplementation in adolescent swimmers with vitamin D insufficiency did not reduce URI burden. However, larger decreases in serum 25(OH)D concentrations were associated with significantly longer and more severe URI episodes.
Kirsty A. Fairbairn, Ingrid J.M. Ceelen, C. Murray Skeaff, Claire M. Cameron, and Tracy L. Perry
people with serum 25-hydroxyvitamin D (25(OH)D) concentrations below 50 nmol/L improves muscle strength, power, and performance ( Glerup et al., 2000 ; Gupta et al., 2010 ). A meta-analysis of nonathletic participants with low vitamin D status reported that vitamin D supplementation improved muscle
Matthew A. Wyon, Roger Wolman, Nicolas Kolokythas, Karen Sheriff, Shaun Galloway, and Adam Mattiussi
48%). 6 Low serum 25(OH)D has been linked to reduced muscle strength and power which are fundamental to athletic performance 6 , 7 ; this has further been associated with an increased incidence of injury. 8 , 9 Vitamin D supplementation has become recommended practice in a number of sports including
Michelle S. Rockwell, Madlyn I. Frisard, Janet W. Rankin, Jennifer S. Zabinsky, Ryan P. Mcmillan, Wen You, Kevin P. Davy, and Matthew W. Hulver
; Jastrzebska et al., 2016 ), interventional studies suggest that vitamin D supplementation increases strength and power in athletes (dancers, taekwondo, and judoka athletes), particularly lower-extremity strength ( Zhang et al., 2019 ). Of note, improved strength and power has primarily been observed as a
Ellen F. Binder
This pilot study evaluated (a) the feasibility of a group exercise program in an institutionalized population with dementia; (b) the effects of such a program on physical performance measures; and (c) the potential additional effects of vitamin D supplementation on gait and muscle strength. Nursing home residents (N = 25) with chronic dementia and mobility impairments attended a thrice weekly exercise class for 8 weeks. They were randomly assigned to receive either a vitamin D supplement or no supplement throughout the program. Between-group differences in the effectiveness of the exercise intervention were analyzed. Pre-to-post changes were also assessed for both groups combined. In postexercise comparisons of both groups, knee extensor torque at 0°/sec declined by 18.6% while performance of 1-RM for hip extension increased by 16.1%. Balance also improved. Although vitamin D levels increased significantly in the supplement group, the two groups did not differ in their response to the exercise intervention.