Clinical review: The effect of vitamin D on falls: a systematic review and meta-analysis.

Systematic review and meta-analysis of 26 randomized trials involving 45,782 adults receiving vitamin D supplementation. Participants were predominantly elderly women at high risk of falls, including community-dwelling and institutionalized older adults, with some hip fracture and stroke populations and variable baseline vitamin D status.

Vitamin D was tested in multiple regimens, including D2 and D3, ranging from 400 IU/day to 500,000 IU annually or intermittent high-dose oral/intramuscular dosing, with durations from 1 month to 62 months. Many active regimens also included calcium, typically about 500 to 1,200 mg/day, and some trials compared vitamin D plus calcium with placebo or calcium alone.

Vitamin D-containing regimens reduced falls overall, but the benefit was driven mainly by trials that coadministered calcium. For the risk of suffering at least one fall, the pooled OR was 0.86 (95% CI 0.77-0.96); for number of falls, OR was 0.79 (95% CI 0.70-0.88), with substantial heterogeneity (I2 = 90%). Vitamin D plus calcium reduced falls versus placebo (OR 0.83, 95% CI 0.72-0.93), whereas vitamin D alone was not statistically significant versus placebo (OR 0.97, 95% CI 0.84-1.11). The effect was stronger in vitamin D-deficient participants (OR 0.53, 95% CI 0.39-0.72) than in nondeficient participants (OR 0.90, 95% CI 0.81-0.99).

Included trials were heterogeneous in population, dose, formulation, route, and duration, and the pooled estimates showed substantial heterogeneity. Most evidence came from elderly women, limiting generalizability to other groups. The overall evidence quality was moderate, with concern for potential publication bias and uncertain optimal dose and target population.