A number of systematic reviews and randomized trials have found evidence that vitamin D prevents falls and fractures in the elderly (JAMA 2004 Apr 28;291(16):1999, but adherence to daily supplements can be problematic for older patients. One way to address this problem might be to give vitamin D less often and use a higher dose. A recent randomized trial evaluated the efficacy of a single annual high-dose vitamin D3 supplement with 2,256 community dwelling women in Australia. Women ? 70 years old, who were at high risk for fractures, were randomized to a single annual oral dose of vitamin D3 (cholecalciferol) 500,000 units vs. placebo. They participated for 3-5 years and were followed for one year after their last dose. The vitamin D3 group experienced a higher rate of falls (83.4 vs. 72.7 per 100 person-years, p = 0.03) and an increase of radiologically-confirmed fractures (4.9 vs. 3.9 per 100 person-years, p = 0.047) (level 1 [likely reliable] evidence). The risk of falls remained significantly higher for the vitamin D3 group after adjustment for baseline calcium intake (JAMA 2010 May 12;303(18):1815).
For more information, see the Vitamin D intake and supplementation topic in DynaMed.