Some authorities recommend vitamin D supplementation to prevent fractures in older people, although results from clinical trials have been mixed. The presumed mechanism for vitamin D's effect on fractures is to strengthen bone. However, because research also suggests that vitamin D deficiency is associated with impaired muscle function, supplementation might also prevent the falls that result in fractures.
Australian researchers randomized 625 older residents of nursing homes and assisted-living facilities (95% women) to receive either supplemental vitamin D (ergocalciferol; 10,000 IU weekly or 1000 IU daily) or placebo. All participants had serum 25-hydroxyvitamin D levels between 25 nmol/L and 90 nmol/L; those with levels lower than 25 nmol/L were excluded on ethical grounds. All subjects also received daily calcium supplementation (600 mg of elemental calcium).
During about 2 years of follow-up, the incidence of falls was significantly lower in the vitamin D group than in the placebo group (1.37 vs. 1.86 falls per person-year). Vitamin D recipients were also less likely than placebo recipients to sustain fractures (8% vs. 11%), but this difference did not reach statistical significance.
In this study, vitamin D supplementation appeared to reduce the incidence of falls among older people in residential care who were not severely deficient in vitamin D at baseline. If these results can be corroborated, supplementation in such populations would be worthwhile, regardless of the effect on fractures.
Reference:
Flicker L et al. Should older people in residential care receive vitamin D to prevent falls? Results of a randomized trial. J Am Geriatr Soc 2005 Nov; 53:1881-8.