More data suggest calcium raises cardiac risk
MedWire News: Latest research has shown further evidence for a link between calcium, or calcium combined with vitamin D supplementation, and cardiovascular disease.
The meta-analysis, published in the BMJ, was conducted by Ian Reid (University of Auckland, New Zealand) and colleagues. Its findings are at odds with the 2006 Women's Health Initiative Calcium/Vitamin D Supplementation Study (WHI CaD Study), which reported no adverse effect of calcium/vitamin D supplementation on any cardiovascular end point.
Bolland and team hypothesized that the large proportion (54%) of participants involved in the WHI CaD trial taking personal calcium supplements may have obscured the link found between calcium and cardiovascular risk. To test this, they decided to reanalyze the dataset to examine cardiovascular events in participants not taking calcium supplements at the start of the study.
The team pooled data from two placebo-controlled trials of co-administered calcium and vitamin D with their reanalysis to determine the effect of calcium and vitamin D on cardiovascular risk. They then updated a previous meta-analysis on calcium supplements that they had already conducted, with data from WHI CaD participants not taking calcium supplements at randomization.
Bolland and colleagues found that among the 46% (n=16,718) of participants not taking calcium supplements at randomization, the hazard ratios for cardiovascular events associated with calcium and vitamin D supplements ranged from 1.13-1.22, with a hazard ratio of 1.21 for myocardial infarction. Conversely, in women already taking calcium supplements, the hazard ratios for the same end points were not significant, ranging from 0.83-1.08 - indicating no alteration of cardiovascular risk.
In an updated meta-analysis of eight other studies incorporating the WHI CaD reanalysis, calcium or calcium plus vitamin D supplements significantly increased the risk of myocardial infarction by 24% and the composite of myocardial infarction or stroke by 15%.
"A reassessment of the role of calcium supplements in osteoporosis management is warranted," the authors state.
In a related editorial in the same journal, Bo Abrahamesen (Gentofte Hospital, Denmark) and Opinder Sahota (Queen's Medical Centre, UK) wrote that though the current study is "particularly relevant," it does not provide definite assurance whether calcium supplements do or do not influence cardiovascular risk.
They concluded: "Further studies are needed and the debate remains ongoing."
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By Piriya Mahendra