Vitamin D deficiency can easily occur in older adults as a result of age-related factors, such as a decrease in time spent outdoors and a diminished ability to absorb vitamin D from the skin. Using systematic review and meta-analysis, researchers sought to determine the overall effects of vitamin D on muscle strength, balance, and gait, as well as the optimal vitamin D dosage, in the older adult population.

The studies analyzed were published between 1980 and 2010. Criteria for inclusion in the review were a randomized controlled study design (with a control arm or placebo and with or without study of coadministered calcium); no evaluation of exercise therapy; a study-population age of 60 years and older; and inclusion of the variables muscle strength, gait, or balance for analysis, evaluated at both study commencement and study end. From among 714 abstracts considered during the initial article screening, 13 trials met all of the inclusion criteria.

All six trials evaluating vitamin D supplementation at 800 IU or more per day showed statistically significant positive changes in balance and muscle strength. Only one study showed a positive effect on balance when a single large dose (600,000 IU) of vitamin D was administered. No significant effects on gait were found in any of the studies.

The meta-analysis focused on the physical performance outcomes body sway and the Timed Up and Go (TUG) test, both measures of balance, and the knee-extension test, which relates to leg strength.

Pooled results from 207 study participants showed a standardized mean difference in body sway among those taking vitamin D of -20, signifying an improvement in balance. Pooled data from 274 participants who completed the TUG test showed a standardized mean difference of -19, indicating a reduction in test completion time and, therefore, better balance; and the standardized mean difference for the knee-extension test was +0.05, indicating an increase in strength.

The results of this analysis showed that daily vitamin D supplementation with 800 IU or more in older adults can improve balance and muscle strength, although it may not improve gait.-AK

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