Vitamin D Supplementation Increases Lower Limb Muscle Strength

SAN DIEGO, CA—Vitamin D supplementation has a positive effect on global muscle strength; specifically, lower limb muscle strength, a meta-analysis presented at the 2013 ACR/ARHP Annual Meeting has found.

Citing evidence that vitamin D plays a role in tissue that includes skeletal muscle and previous studies have suggested a deficiency of vitamin D is associated with low muscular strength, Charlotte Beaudart, PhD Candidate, of the Department of Public Health, Epidemiology and Health Economics at the University of Liège, Liège, Belgium, and colleagues examined systematic research of randomized controlled trials that assessed the effect of vitamin D supplementation on muscle strength conducted between 1966 and February 2013.

Data sources included Medline, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, a manual review of the literature and congressional abstracts. The quality of the randomized controlled trials was evaluated using Jadad criteria.

“All forms and doses of vitamin D supplementation, with or without calcium supplementation, compared with placebo or control were included,” Beaudart reported. “Muscle strength was assessed either by grip strength and/or lower limb muscle strength.”

Of 214 articles, 19 randomized controlled trials met the inclusion criteria, with a mean quality Jadad score of 3.8 (of 5) points. A total of 4,824 individuals were included; mean age was 66 years.

“Results reveal a significant positive effect of vitamin D supplementation on global muscle strength with a standardized mean difference (SMD) of 0.096 (95% CI 0.007–0.184; P=0.034),” the investigators reported.

No significant between-study heterogeneity (Q-value 23.6; P=0.21; I²=19.6%) or publication bias were found.

Of the studies, 13 assessed the effect of vitamin D supplementation on grip strength and 15 on lower limb muscle strength. No significant effect of vitamin D supplementation was shown on grip strength (SMD=0.062, P=0.264); however, a significant positive effect on lower limb muscle strength was observed (SMD=0.169, P=0.03).
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