Higher doses of vitamin D supplementation appeared to decrease risk for fracture among older patients, according to data published in the New England Journal of Medicine.
Data regarding the effects of vitamin D supplementation have been inconsistent — a problem that may be related to varying study criteria, researchers wrote. “The discordant findings may be explained, in part, by differences in the criteria for including trials in the analyses, with respect to blinding, vitamin D formulation (oral vs. injectable), or accommodations for non-adherence. Our analysis was designed to estimate the effects of vitamin D supplementation according to the actual intake of each participant, rather than simply the dose to which the participant was randomly assigned.”
For their meta-analysis, the researchers included 11 double blind, randomized, controlled trials comparing oral vitamin D supplementation, with or without calcium, with placebo or calcium alone in participants aged at least 65 years.
A total of 31,022 participants (mean age, 76 years; 91% women) with 1,111 incident hip fractures and 3,770 nonvertebral fractures were included in the study. Results revealed a nonsignificant 10% reduction in the risk for hip fracture (HR=0.9; 95% CI, 0.8-1.01) and a 7% reduction in the risk for nonvertebral fracture (HR=0.93; 95% CI, 0.87-0.99) among participants assigned to vitamin D vs. those assigned calcium alone or placebo.
However, data demonstrated a significant reduction in risk for fracture among participants in the highest quartile of actual vitamin D intake only (800 IU daily; range, 792 IU to 2,000 IU). In this group, the researchers noted a 30% reduction in the risk for hip fracture (HR=0.7; 95% CI, 0.58-0.86) and a 14% reduction in the risk for any nonvertebral fracture (HR=0.86; 95% CI, 0.76-0.96). These results remained fairly consistent across subgroups, including age, type of dwelling, baseline 25-hydroxyvitamin D level and additional calcium intake, the researchers wrote.
In an accompanying editorial, Robert P. Heaney, MD, of the Osteoporosis Research Center, Creighton University Medical Center in Omaha Neb., said the study supports current recommendations regarding vitamin D.
“Given the congruence of the findings of this latest meta-analysis with the guidelines from the Endocrine Society, it would appear to be prudent, and probably helpful as well, to ensure an intake at the upper end of the range at which Bischoff-Ferrari et al. found a reduction in fracture risk,” he wrote.
For more information:
Bischoff-Ferrari HA. N Engl J Med. 2012;367:40-49.
Heaney RP. N Engl J Med. 2012;367:77-78.
Disclosure: See the study for a full list of disclosures. Dr. Heaney is a consultant for the International Dairy Foods Association; has provided expert testimony for the Federal Trade Commission; has received lecture fees from the National Dairy Council; has received payment for manuscript preparation from the Council for Responsible Nutrition; and has received payment for the development of education programs from the Coca-Cola Company.