Vitamin D supplementation with or without calcium does not reduce skeletal or non-skeletal outcomes in the general population by more than 15%, a meta-analysis concluded.
Researchers in New Zealand did a meta-analysis of vitamin D trials, with or without calcium, to estimate the effects of supplementation on myocardial infarction or ischemic heart disease, stroke or cerebrovascular disease, cancer, total fracture, hip fracture, and mortality. They used a risk reduction threshold of 5% for mortality and 15% for the other conditions.
Results appeared online Jan. 24 at The Lancet.
The effect estimates all were within the futility boundary, researchers noted, showing that vitamin D does not alter the relative risk of any of these endpoints:
• Vitamin D supplementation alone did not reduce hip fracture by 15% or more (12 trials, 27,834 patients);
• Vitamin D co-administered with calcium reduced hip fracture in institutionalized individuals (2 trials, 3,853 patients);
• Vitamin D did not alter the relative risk of hip fracture by 15% or more in community-dwelling individuals (7 trials, 46,237 patients); and
• There was uncertainty whether vitamin D with or without calcium reduces the risk of death (38 trials, 81,173 patients).
Researchers noted that vitamin D with calcium reduced hip fractures in two trials of institutional settings, and that it supplementation had uncertain whether there were small effects on mortality. Yet, future trials with similar designs are unlikely to alter these conclusions because the results of several large trials were so heterogeneous, researchers wrote.
“In view of our findings, there is little justification for prescribing vitamin D supplements to prevent myocardial infarction or ischaemic heart disease, stroke or cerebrovascular disease, cancer, or fractures, or to reduce the risk of death in unselected community-dwelling individuals,” researchers wrote. “Investigators and funding bodies should consider the probable futility of undertaking similar trials of vitamin D to investigate any of these endpoints.”
The study trails on the heels of findings that vitamin D may still have uses in other specific populations. Higher vitamin D levels appear to be associated with reduced disease activity and a slower rate of disease progression in multiple sclerosis patients treated with interferon beta-1b, according to the study.