High-dose vitamin D supplementation was somewhat favorable in preventing hip fracture and any nonvertebral fracture in persons aged 65 years and older in a Swiss study that appeared recently in the New England Journal of Medicine. Researchers pooled participant-level data from 11 double-blind, randomized, controlled trials of oral vitamin D supplementation, with and without calcium, compared with placebo or calcium alone. The primary goal was to compare data from quartiles of actual intake of vitamin D in the treatment groups of all trials with data from the control groups, including each patient's adherence to the treatment regimen and supplement use outside the study protocol.
There was a nonsignificant 10% reduction in the risk of hip fracture and a 7% reduction in the risk of nonvertebral fracture in patients who were randomly assigned to receive vitamin D compared with those assigned to control groups. By quartiles of actual intake, reduction in fracture risk was shown only at the highest intake level (median, 800 IU/d; range, 792 to 2000 IU/d), with a 30% reduction in hip fracture risk and a 14% reduction in the risk of any nonvertebral fracture. Benefits at the highest level of vitamin D intake were somewhat consistent across age-group, type of dwelling, baseline 25-hydroxyvitamin D level, and additional calcium intake subgroups.