Thirteen studies with 2,496 participants were included in the review.
Four trials compared vitamin D alone with placebo, of which two were considered to be of a high quality. One of these studies (n=354) found no difference between the groups in the risk of falling over a 28-week period; the odds ratio was 1.0 (95% CI: 0.6, 1.5). The second study (n=243) found no differences over 6 months between groups on any of the outcomes measured: falls, self-reported health, physical function and several measures of physical performance. Two other studies also found no difference between the treatment and placebo groups.
Two trials compared a vitamin D analog with placebo. One study (n=98) compared 1,25 hydroxyvitamin D2 with placebo in adults over 70 years. No differences were found on any of the measures of strength used. The other study (n=86) compared 1 alpha-hydroxyvitamin D3 with placebo over 18 months in patients with Parkinson's disease. There was no significant difference in the occurrence of falls, but a benefit of vitamin D was found in the incidence of fractures: one fracture in the intervention group versus eight in the placebo group.
Four trials compared vitamin D plus calcium with calcium supplementation alone, of which two were considered to be of a high quality. One study (n=148) looked at older women and found the combined supplement to be of significant benefit in terms of the number of participants falling and the total number of falls occurring after 8 weeks. An improvement in two of the three measures of body sway was also found. The second study (n=122) found a significant reduction in falls after 12 weeks of the combined supplement.
Three trials compared calcium plus vitamin D with placebo. The largest study (n=583) found a decreased risk of hip fracture in older women, but no difference in the number of participants experiencing falls. Another study (n=445) looked at healthy participants aged over 65 years and found significantly fewer nonvertebral fractures in the treatment group. However, there was no difference in the proportion of participants who fell, and the number of falls per person was slightly elevated in the supplementation group. The third study (n=139) also looked at older women and found no difference in clinical outcomes between the groups.
A meta-analysis of the 4 high-quality studies for which data were available pooled data on the number of participants who fell. The pooled estimate of the RR showed no benefit of vitamin D (RR 0.99, 95% CI: 0.89, 1.11) although one study comparing vitamin D plus calcium with calcium alone showed a trend towards fewer people falling in the combined group (RR 0.55, 95% CI: 0.29, 1.08).