Bischoff-Ferrari HA, Willett WC, Wong JB, et al: Fracture prevention with vitamin D supplementation: a meta-analysis of randomized controlled trials. JAMA 2005;293(18):2257-64.
The researchers pooled data from five randomized controlled trials for hip fracture (n = 9294) and seven for nonvertebral fracture (n = 9820) to compare the benefit of oral vitamin D supplementation with or without calcium to calcium supplementation or placebo in persons older than 60 years. A vitamin D dose of 700 to 800 international units reduced the relative risk of fracture by 23% to 26% compared to placebo or calcium. No significant benefit was observed in trials using 400 units daily of vitamin D, suggesting that the lower dose is not sufficient for fracture prevention. These data may lead to a change in the current recommendations for 400 to 600 units of vitamin D in middle-aged and older adults.