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 D 3 per month or 24 000 IU vitamin D 3 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 D 3 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%.