Summary of evidence-based review on vitamin D efficacy and safety in relation to bone health.

The objective of this evidence review was to synthesize the literature on the effectiveness and safety of nutritional and ultraviolet radiation sources of vitamin D with respect to bone health outcomes at all stages of life. The goals were to identify knowledge gaps for the research community and to highlight areas that required further research. We completed an extensive literature search of multiple databases and a multilevel selection process with synthesis of results from 167 included studies. We included a variety of outcomes (eg, falls, bone mineral density, fractures, and adverse events). This report provides an overview of the methods and a summary of the key findings. In addition, we discuss areas where the evidence is inconclusive, as well as methodologic issues that we encountered. We found inconsistent evidence of an association between serum 25-hydroxyvitamin D [25(OH)D] concentration and bone mineral content in infants and fair evidence of an association with bone mineral content or density in older children and older adults. The evidence of an association between serum 25(OH)D concentration and some clinical outcomes (fractures, performance measures) in postmenopausal women and older men was inconsistent, and the evidence of an association with falls was fair. We found good evidence of a positive effect of consuming vitamin D-fortified foods on 25(OH)D concentrations. The evidence for a benefit of vitamin D on falls and fractures varied. We found fair evidence that adults tolerated vitamin D at doses above current dietary reference intake levels, but we had no data on the association between long-term harms and higher doses of vitamin D.