High-dose vitamin D does not reduce falls, fractures in healthy adults
High-dose, monthly vitamin D3 supplementation does not reduce the risk of falls or fractures in healthy, older adults, according to a secondary and post-hoc analysis of the ViDA* trial.
“These findings – taken in conjunction with results from other trials – suggest that use of large monthly bolus doses of vitamin D does not confer overall benefit,” said the researchers led by Professor Kay-Tee Khaw from the University of Cambridge School of Clinical Medicine, Cambridge, UK. They called for further study to determine the effects of daily vitamin D doses, with or without concurrent calcium supplementation. [Lancet Diabetes Endocrinol 2017;doi:10.1016/S2213-8587(17)30103-1]
In this double-blind study conducted in New Zealand, individuals aged 50–84 years (mean age 65.9 years, 58 percent male, mean blood concentration of 25(OH)D at baseline, 63 nmol/L) were randomized to receive colecalciferol (vitamin D3, initial oral dose of 200,000 IU [5 mg] followed by 100,000 IU [2.5 mg] monthly, n=2,558) or placebo (n=2,552).
After a mean treatment duration of 3.4 years, incidence of one or more falls was comparable between individuals on vitamin D and placebo (52 percent [n=1,312] vs 53 percent [n=1,326], adjusted hazard ratio [adjHR], 0.99, 95 percent confidence interval [CI], 0.92–1.07; p=0.82).
The incidence of nonvertebral fractures was also similar between individuals on vitamin D and placebo (6 percent [n=156] vs 5 percent [n=136], adjHR, 1.19, 95 percent CI, 0.94–1.50; p=0.15).
In an accompanying commentary, Professor Roger Bouillon from the Clinical and Experimental Endocrinology unit at KU Leuven, Leuven, Belgium, advised caution when interpreting these findings, as the primary outcome of the trial was to identify cardiovascular effects of high-dose vitamin D supplementation, and that the study may not have been adequately powered to determine fracture prevention risk. [Lancet Diabetes Endocrinol 2017;doi:10.1016/S2213-8587(17)30140-7]
While the study was powered to assess the impact of vitamin D supplementation on falls, individuals with severe vitamin D deficiency tend to derive the most benefit from supplementation and very few participants in this study met this criteria, said Bouillon. Other studies have found an increased risk of falls and fractures following high annual doses of colecalciferol, he said. [JAMA 2010;303:1815-1822]
“Khaw and colleagues are prudent to make clear that their results show that higher than recommended doses given monthly do not benefit adults with a baseline vitamin D status that is regarded as fairly normal,” said Bouillon.