Ian R. Reid, MD, from the University of Auckland in New Zealand, and colleagues reviewed the literature to examine the effect of vitamin D supplementation on bone mineral density. Twenty-three randomized trials which compared interventions that differed only in vitamin D content were included in the analyses (comprising 4,082 participants without other metabolic bone disease).
The researchers found that, in each study, bone mineral density was measured at one to five sites (lumbar spine, femoral neck, total hip, trochanter, total body, or forearm), and across the studies, 70 tests of statistical significance were conducted. Overall, six findings indicated significant benefit, two indicated significant detriment, and the remaining findings were non-significant. Benefit at more than one site was found in only one study. In meta-analysis there was a small benefit seen at the femoral neck (weighted mean difference, 0.8%), with heterogeneity between the studies (I²=67%). There was no effect reported at other sites. Bias toward positive results was noted at the femoral neck and total hip.
“Continuing widespread use of vitamin D for osteoporosis prevention in community-dwelling adults without specific risk factors for vitamin D deficiency seems to be inappropriate,” the authors write.