Efficacy of Vitamin D3 Supplementation on Physical Performance in Community-Dwelling Older Adults

Background: Impaired lower extremity muscular strength and mobility are major risk factors for falls in elderly. Vitamin D insufficiency has as well been associated with increased risk of falls and impaired physical performance. In addition, vitamin D receptors (VDR) have been identified in muscle fibers, suggesting that vitamin D has a direct effect on muscle tissue. These effects are thought to be mediated through genomic and non-genomic pathways and also through inhibition of muscle inflammation, which is often observed in elderly. Methods: The present randomized parallel double-blinded placebo-controlled pilot study was proposed to investigate the effect of a daily dose of 50 μg (2000 IU) vitamin D3 (n=0) or placebo (n=5) on physical performance parameters in Danish elderly (72.8 ± 5.5 years) at baseline and after 12 weeks of treatment. Primary outcomes were maximal muscle strength (MVC) and Timed Up and Go (TUG) Test. Secondary outcomes, in this study, were pressure pain threshold (PPT), Berg’s Balance Scale, EQ-5D-5L, Falls Efficacy Scale-International, fall diaries and 25(OH)D serum levels. Results: All subjects were allocated placebo treatment, why comparisons of treatment groups were not possible. Paired t-tests for the two time points showed significant differences for MVC (p = 0.01) and TUG (p = 0.05). For secondary outcomes, only 25(OH)D serum levels were found to be significantly increased post-treatment (p = 0.02). Furthermore, correlations between outcomes and 25(OH)D levels were examined, revealing that 25(OH)D serum levels correlated positively with PPT post-treatment (test point 1 (TP1) r = 0.913, p = 0.031 and test point 2 (TP2) r = 0.964, p = 0.008). Conclusion: In the present study it was not possible to conclude whether a daily dose of 50 μg vitamin D3 is able to improve muscle strength or time to complete the TUG test in elderly after 12 weeks of treatment.