Traditionally vitamin D has been recommended with respect to preventing osteoporosis, reasoning that improving the absorption of calcium improves bone strength making them less likely to fracture, should there be a fall. Thereafter it was discovered that vitamin D has direct effects on muscle strength. Severe vitamin D deficiency (as one might see in those nursing home residents who do not eat well and are virtually never in the sun) can present as muscle weakness and pain which resolves with vitamin D supplementation.
Several early trials examining the extent to which vitamin D could prevent falls were unsuccessful. These studies may have failed to produce the hypothesized result due to methodological issues: low doses of vitamin D were used; vitamin D is available over-the-counter and may have been in use by those in the control group creating bias toward the null; and finally an issue we can all identify with — the difficulties associated with ascertaining the prevalence of falls due to using an unstandardized definition or incomplete ascertainment.
A meta-analysis (“study of studies”) conducted by an international team of researchers, was recently published in the British Medical Journal1 to further address this issue. The meta-analysis included 8 double blind randomized controlled trials of individuals 65 years or older receiving a defined oral dose of supplemental vitamin D3, vitamin D2 or an active form of vitamin D and with sufficiently robust fall ascertainment. The aim was to assess the efficacy of vitamin D supplementation for the prevention of falls among older persons by dose and serum concentration of vitamin D [25(OH)D]. The primary outcome measure was the relative risk of having at least one fall among persons receiving vitamin D (with or without calcium) compared to those receiving placebo or calcium supplementation alone. Note that the current recommended adult daily dose of vitamin D is 400 international units.
No fall reduction was observed for a daily dose of less than 700 IU vitamin D or achieved serum 25(OH)D concentrations below 60 nmol/l.
Daily vitamin D doses in the range of 700 IU to 1000 IU or achieved serum concentrations between 60 nmol/l and 95 nmol/l reduced the risk of fallingby 19%. It is possible that higher doses of vitamin D or higher 25(OH)D concentrations would further reduce falls. Results were attained with treatment for less than a year (2-5 months) and the benefit was sustained for 12-36 months.
Preventing falls using this higher dose of vitamin D may not depend on taking additional calcium.
The authors note: “Binding of vitamin D to its nuclear receptor in muscle tissue may lead to de novo protein synthesis, a benefit that appears to precede the effect of vitamin D on bone.”
*Since vitamin D is fat soluble and stored in the body it can accumulate to toxic levels over time and therefore periodic blood levels should be assessed.
1. Bischoff-Ferrari HA, Dawson-Hughes B, Staehelin HB, Orav JE, Stuck AE, Theiler R, Wong JB, Egli A, Kiel DP and Henschkowski J. Fall prevention with supplemental and active forms of vitamin D: a meta-analysis of randomized controlled trials. BMJ 2009; 339:b3692.