How does Vitamin D prevent falls? ( if it does)

Bischoff-Ferrari et al published a meta-analysis in the April 28, 2004 JAMA indicating an approximately 20% decrease in falls in elderly patients treated with vitamin D ( 800 - 1000 u/day).The authors quote several lines of evidence indicating a beneficial muscle strengthening effect of Vitamin D.The effect was evident fairly quickly- noted in 2-3 months in 2 of the 5 studies including in the analysis. A more recent study from a Boston nursing home showed results in the same direction but claimed a 70% reduction in risk of falls.If the only evidence of efficacy were this single study,few would be convinced.However,when placed in the context of the 2004 meta-analysis ,a reasonably possible mechanistic explanation,vitamin D safety in the dose range used, and the importance of falls in the elderly I feel confident that supplementation of 800 U vit. D/day in nursing home residents makes sense. Besides it is necessary for the bones. The meta-analysis was helpful, taking several fairly small RCTs that showed results in the same direction but not all statistically significant and combining them into a composite result that was significant.