Possible harm to seniors' fall risks with higher doses of vitamin, study finds

Large doses of vitamin D supplements were no better at preventing falls in people age 70 and older than a low dose, according to a new study by Johns Hopkins Medicine published in the Annals of Internal Medicine.

The study, funded by the National Institute on Aging, showed that 1,000 or more international units (IU) per day, equivalent to 25 micrograms per day of vitamin D, were no better than 200 IU per day at preventing falls, a dose about half of the typical amount in multivitamins, according to the study.

Preliminary studies show that vitamin D may increase muscle strength and improve balance. In the study, called the Study to Understand Fall Reduction and Vitamin D in You (STURDY), vitamin D supplement doses of 2,000 and 4,000 IU per day appeared to increase the risk of falls compared with 1,000 IU per day, a relatively common dose for a pure vitamin D supplement. In addition, serious falls and falls with hospitalization occurred more frequently in persons assigned to 1,000 or more IU per day compared with those assigned to 200 IU per day.

The trial had two phases. During the first phase, known as the dose-finding phase, participants were assigned to one of four doses of supplemental vitamin D: 200 IU per day (the control dose), 1,000 IU per day, 2,000 IU per day, and 4,000 IU per day.

In the first phase, the fall rates in the three higher-dose groups were compared to see which of the higher doses had the lowest fall rate. The 1,000 IU per day dose group had a lower fall rate than the 2,000 IU per day and 4,000 IU per day groups, so it was identified in the first phase as the dose to test in the second phase, also called the confirmatory phase, according to the study. In the confirmatory phase, the fall rate in the higher-dose group (1,000 IU per day) was compared with the fall rate in the control group (200 IU per day). The team found that 1,000 IU per day of vitamin D was no better than 200 IU per day at preventing falls.

The researchers said they recommend that seniors discuss their fall risk and vitamin D level with their doctors and decide whether to continue vitamin D supplements.