By Sarah Guy
The results of a meta-analysis of individual patient data (IPD) show that vitamin D supplementation with calcium reduces mortality rates in the elderly.
Overall, the findings showed that with or without calcium, vitamin D was associated with a 7% reduction in mortality over a 3-year period, however, the association only became significant when the supplement was combined with calcium, giving a 9% reduction in risk for death.
"Accordingly, calcium with vitamin D supplementation to elderly participants is overall not harmful to survival, and may have beneficial effects on general health," say Lars Rejnmark (Aarhus University, Denmark) and colleagues.
Recent research has emphasized the role of vitamin D in a large number of tissues with the appropriate receptors, indicating it may be necessary for various physiologic functions beyond bone and mineral metabolism, the team remarks in the Journal of Clinical Endocrinology and Metabolism.
Using data from eight studies, Rejnmark and co-workers conducted IPD-level analysis on 27,345 individuals randomly assigned to receive vitamin D with calcium, 7,771 individuals assigned to vitamin D alone, and 35,412 who received placebo or no vitamin D.
The cohort was aged a mean 70 years, and 87% was female, of whom 34% received hormone replacement therapy (HRT); however, HRT use did not significantly affect mortality rates, observes the research team.
During the 36-month follow-up period studied, 3832 (5.4%) participants died, and 1139 (1.6%) sustained an osteoporotic fracture at the hip or spine, report the researchers.
After adjustment for factors including age, gender, fractures, and HRT use, the risk for death among all the studies' participants was 7% less in those assigned to take vitamin D alongside or without calcium compared with their peers who were assigned to placebo/no vitamin D.
When Rejnmark and co-authors included only the studies with a group assigned to vitamin D plus calcium supplementation, the risk for death was significantly reduced among these participants compared with their counterparts who received placebo or no vitamin D (hazard ratio=0.91).
This equated to an absolute risk reduction of 0.66%, and the need to treat 151 individuals for 3 years to prevent one death.
The researchers suggest that their finding that vitamin D plus calcium, but not vitamin D alone, reduces the risk for mortality in this older population could be a result of calcium reducing the overall cancer risk, having some effect in preventing osteoporotic fractures, and simply that, when given together, the supplements have a greater impact than when given individually.
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