The effect of vitamin D supplementation on fall risk in older adults has been uncertain, but in the recently published VITAL trial, which involved 26,000 participants, 2000 IU daily of vitamin D3 did not prevent falls. This randomised trial involved a two-stage design to determine the effect of three different doses of vitamin D on fall risk.
In the first stage, participants were assigned to take 1000, 2000, or 4000 IU/day of vitamin D3 or to a control group who received 200 IU/day. When prespecified interim analyses showed higher rates of falls and adverse events in the two highest-dose groups, those participants were reassigned to 1000 IU/day, and subsequent enrollees received either 1000 IU or 200 IU.
In the second stage, the 1000 IU/day group was compared with the control group. During 2 years of follow-up, there was no difference in the primary outcome (i.e., time to first fall or death).
In this study, vitamin D supplementation at doses of 1000 IU daily or higher did not prevent falls, and fall risk increased with higher doses. These outcomes, along with those of other recent studies, convincingly show that vitamin D supplementation does not prevent falls and might cause harm in community-dwelling older adults.