Study results have revealed that women aged 70 and over who received a single annual high-dose of vitamin D were more likely to suffer a fall and/or sustain a fracture compared to women given a placebo. Kerrie M. Sanders, Ph.D., of the University of Melbourne (Australia), and colleagues conducted a study to examine whether high-dose vitamin D (500,000 IU) given orally once a year to older women would reduce the incidence of falls and fractures. A single, high-dose was administered in order to address low adherence and to be a practical intervention easily translated to clinical practice. Results showed that women treated with high-dose vitamin D experienced 15% more falls and sustained 26% more fractures. Furthermore, treated women not only experienced excess fractures after more frequent falls but also experienced more fractures that were not associated with a fall. The authors concluded: "This is the first study to demonstrate increased risk of falls associated with any vitamin D intervention and the second study to demonstrate an increased fracture risk associated with annual high-dose vitamin D therapy in elderly women. Our study used the largest total annual dose of vitamin D (500 000 IU) reported in any large randomized controlled trial, raising the possibility that the adverse outcome is dose-related...because the levels of 25-hydroxycholecalciferol demonstrated in this study could occur with other recommended dosing regimens, the outcome of this study suggests that safety of high-dose vitamin D supplementation warrants further study."