They carried out a randomised trial of 301 women aged 70–90 with vitamin D deficiency and a history of falling. Half received 1,000IU a day of ergocalciferol for a year and the remainder a placebo. Both groups also received 1,000mg per day of calcium citrate.
The authors found the supplement group had a 19% reduction in the relative risk of falling, compared with the controls. The effect was most prevalent in winter when it was less sunny, they said.
Archives of Internal Medicine (2008) 168: 103–108