Prevention of Nonvertebral Fractures With Oral Vitamin D and Dose Dependency

Abstract

The antifracture benefits of vitamin D have been questioned by several recent trials,^1-4 leading to uncertainty among patients and physicians regarding recommendations for vitamin D supplementation. Two 2007 meta-analyses^5,6 included most of these trials and concluded that vitamin D may not reduce fractures significantly or may do so only in combination with calcium and primarily among institutionalized older individuals. A third 2007 meta-analysis⁷ concluded that calcium with or without vitamin D may reduce total fracture risk by 12%, a result that was questioned by a more recent meta-analysis⁸ of high-quality trials of calcium supplementation alone in which calcium had a neutral effect on nonvertebral fractures and a possible adverse effect on hip fracture risk. Apart from the mixed data on calcium, the recent meta-analyses with vitamin D did not consider heterogeneity by received dose (incorporating adherence) or achieved level of 25-hydroxyvitamin D.