The randomized clinical trial (RCT) by Bischoff-Ferrari et al1 in this issue of JAMA Internal Medicine shows that vitamin D supplementation is associated with the risk of falls. Two “high” doses (60 000 IU of vitamin D3 per month or 24 000 IU vitamin D3 plus 300 mg of calcifediol per month) achieved a serum 25-hydroxyvitamin D (25[OH]D) level of 30 ng/mL in 80% of participants, a level that has been recommended as best for reducing the risk of fractures and for other health benefits (to convert 25[OH]D to nanomoles per liter, multiply by 2.496).2,3 However, compared with a dose of 24 000 IU of vitamin D3 per month (equivalent to 800 IU per day), the higher doses had no effect on lower extremity physical performance and increased the risk of falls. A previous RCT4 in women of the same age showed that 500 000 IU of vitamin D per year achieved serum 25(OH)D levels of at least 30 ng/mL in most participants but significantly increased risk of falls by 15% and fractures by 26%.
Cummings SR, Kiel DP, Black DM. Vitamin D Supplementation and Increased Risk of Falling: A Cautionary Tale of Vitamin Supplements Retold. JAMA Intern Med. 2016;176(2):171–172. doi:10.1001/jamainternmed.2015.7568
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