KoKo Aung, MD, MPH, FACP
In older adults, does vitamin D supplementation improve balance, muscle strength, and gait? Do effects differ by treatment dose?
Included studies compared supplemental vitamin D or an associated metabolite, with or without calcium, with placebo or standard treatment in adults ≥ 60 years of age and measured physical performance at baseline and study end. Studies or treatment groups that included an exercise intervention were not considered. Physical performance outcomes were balance, muscle strength, and gait.
MEDLINE, EMBASE/Excerpta Medica, and the Cochrane Library (1980 to Nov 2010); and reference lists were searched for randomized controlled trials (RCTs). 12 RCTs (n = 2146, mean age 78 y, 85% women, study duration 2 to 36 mo) met inclusion criteria: 6 evaluated cholecalciferol, 3 ergocalciferol, 2 calciferol, and 1 calcitriol. 2 RCTs used single-dose vitamin D (n = 382); 1 used monthly dose vitamin D (n = 56); 4 used vitamin D at a dose < 800 IU/d (n = 798); and 5 used vitamin D at a dose ≥ 800 IU/d (n = 910). 7 of 8 studies used the Timed Up and Go (TUG) test and/or body sway to measure balance; assessments for other outcomes varied. 4 RCTs scored ≥ 16 out of 32 on the Downs and Black scale (higher scores = better methodological quality).
Data were sufficient for meta-analysis in 3 of 12 studies for each outcome. Meta-analysis showed that vitamin D supplementation decreased time to complete the TUG test but did not improve knee extension strength (Table). Meta-analysis showed that vitamin D supplementation reduced balance sway; the effect was not maintained in a sensitivity analysis that excluded 1 low-quality study (Table). In 5 individual studies of vitamin D at doses ≥ 800 IU/d, 2* of 4 reported a benefit with vitamin D compared with control (P < 0.05) for balance, 2* of 3 for muscle strength, and 1 of 1 for a summary score. In 4 individual studies of vitamin D at doses < 800 IU/d, 0 of 2 reported a benefit with vitamin D for balance, 1 of 2 for gait, and 0 of 4 for muscle strength. In 3 other individual studies, single-dose vitamin D improved balance more than control in 1 study, and monthly dose vitamin D improved muscle strength in 1 study.
Vitamin D supplementation improves some measures of balance but not muscle strength in older adults.
Vitamin D supplementation vs control in adults ≥ 60 years of age†
†SMD = standardized mean difference; other abbreviations defined in Glossary.
‡Negative values indicate benefit with vitamin D supplementation.
§Sensitivity analysis excluding 1 low-quality study: 2 trials, n = 365, SMD −0.17, 95% CI −0.38 to 0.03.
||Positive values indicate benefit with vitamin D supplementation.
KoKo Aung. Review: Vitamin D supplementation improves some balance measures but not muscle strength in older adults. Ann Intern Med. 2012;156:JC5–8. doi: 10.7326/0003-4819-156-10-201205150-02008
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Published: Ann Intern Med. 2012;156(10):JC5-8.
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