Vitamin D Supplements and Future Fracture Risk among Mongolian Schoolchildren

We thank Ning Ma and colleagues for their comments on our work.1 With regard to ethics, our protocol was reviewed and approved by institutional review boards in both Mongolia and the USA, and the trial was monitored by an external data and safety monitoring board whose members were independent of the study. Random assignment of children with unknown but potentially low baseline serum 25-hydroxyvitamin D concentrations to vitamin D versus placebo was approved by all these parties on the grounds that evidence supporting health benefits of weekly vitamin D supplementation in the study population (which excluded children with signs of rickets) was equivocal, and that a situation of ethical equipoise therefore existed.