Effect of vitamin D supplementation on muscle strength, gait and balance in older adults: a systematic review and meta-analysis.

OBJECTIVES: To systematically review and quantitatively synthesize the effect of vitamin D supplementation on muscle strength, gait, and balance in older adults.

DESIGN: Systematic review and meta-analysis.

SETTING: MEDLINE, EMBASE, Cochrane Library, bibliographies of selected articles, and previous systematic reviews were searched between January 1980 and November 2010 for eligible articles.

PARTICIPANTS: Older adults (≥60) participating in randomized controlled trials of the effect of supplemental vitamin D without an exercise intervention on muscle strength, gait, and balance.

MEASUREMENTS: Data were independently extracted, and study quality was evaluated. Meta-analysis using a fixed-effects model was performed and the I(2) statistic was used to assess heterogeneity.

RESULTS: Of 714 potentially relevant articles, 13 met the inclusion criteria. In the pooled analysis, vitamin D supplementation yielded a standardized mean difference of -0.20 (95% confidence interval (CI) = -0.39 to -0.01, P = .04, I(2)  = 0%) for reduced postural sway, -0.19 (95% CI = -0.35 to -0.02, P = .03, I(2)  = 0%) for decreased time to complete the Timed Up and Go Test, and 0.05 (95% CI = -0.11 to 0.20, P = .04, I(2)  = 0%) for lower extremity strength gain. Regarding dosing frequency regimen, only one study demonstrated a beneficial effect on balance with a single large dose. All studies with daily doses of 800 IU or more demonstrated beneficial effects on balance and muscle strength.

CONCLUSION: Supplemental vitamin D with daily doses of 800 to 1,000 IU consistently demonstrated beneficial effects on strength and balance. An effect on gait was not demonstrated, although further evaluation is recommended.