Background: Each year, one third of adults 65 years and older have at least one fall; 9 percent of those falls require an emergency department visit and up to 6 percent result in a fracture. Consequently, strategies to prevent falls have become a public health goal. Some studies of vitamin D supplementation in older adults have shown improved strength, function, and balance in addition to reduced falls. Other studies have not found any benefit, which may be attributed to differences in dosing and the use of open trial designs. Vitamin D is now available as an over-the-counter supplement (vitamin D₃ or vitamin D₂), or in an active form (1α-hydroxyvitamin D₃ or 1,25-dihydroxyvitamin D₃). Bischoff-Ferrari and colleagues conducted a meta-analysis to determine the effectiveness of various vitamin D formulations on the prevention of falls in older persons.

The Study: The authors searched for articles in Medline and the Cochrane central register of controlled trials from 1960 to 2008, in BIOSIS from 1985 to 2008, and in EMBASE from 1991 to 2008. Additional studies were identified through review of reference lists and abstracts. Inclusion criteria included randomized, double-blind, controlled clinical trials of fall prevention using defined dosages and types of vitamin D in adults 65 years and older. Falls needed to be specifically defined and assessed, and follow-up had to last at least three months. Nonrandomized trials and those with populations at higher than average risk of falls (i.e., persons with Parkinson disease or in acute hospitalizations) were excluded. The primary outcome was the risk of at least one fall while on vitamin D supplementation, with or without calcium, compared with persons on placebo or on calcium alone.

Results: Of 164 articles identified, 10 were included in the final analysis; five trials used vitamin D₃, three used vitamin D₂, and two studied active forms of vitamin D. Of the 2,426 participants in the eight trials of vitamin D₂ or D₃, the average age was 80 years, and 81 percent were women. All participants were in stable health and were living in the community or in nursing homes. Daily dosages ranged from 200 IU to 1,000 IU during a treatment course of two to 36 months. Calcium supplementation (500 to 1,200 mg per day) was used in both the treatment and placebo arms in five trials, was used only in the treatment group of one trial, and was not used in two studies (vitamin D compared with placebo). In seven of the eight trials, the rate of adherence was reported to be 80 to 100 percent.

Among the seven high-dose trials (i.e., those that used 700 to 1,000 IU of supplemental vitamin D per day), dose stratification showed that daily dosages of 700 IU or more resulted in a relative risk reduction of 19 percent; subgroup analysis of the trials using high-dose vitamin D₃ showed a fall reduction of 26 percent. For all supplemental vitamin D, the number needed to treat was 11 for two to 36 months to achieve significant fall reduction. Dosages of less than 700 IU per day did not confer any benefit in reducing falls. Serum 25-hydroxyvitamin D levels of 24 ng per mL (60 nmol per L) or more were associated with a 23 percent reduction in falls. In a subgroup analysis of the high-dose trials, there were no significant differences among participants who used calcium supplementation and those who did not. Finally, the two studies using the active forms of vitamin D showed a relative risk reduction similar to that of the supplemental forms, but had twice the hypercalcemia rate compared with placebo.

Conclusion: The authors conclude that vitamin D supplementation taken in dosages of 700 to 1,000 IU per day to achieve a serum 25-hydroxyvitamin D level of at least 24 ng per mL can reduce falls in older persons. Active forms of vitamin D are no more effective than supplemental vitamin D.