London: Calcium supplements, commonly taken by older people for osteoporosis, increase the risk of a heart attack, according to a new study.
An international team of researchers analysed the results of 11 randomised controlled trials of calcium supplements (without co-administered vitamin D) involving 12,000 patients.
Differences in study design and quality were taken into account to minimize bias.
They found that calcium supplements were associated with about a 30 percent increased risk of heart attack and smaller, non-significant, increases in the risk of stroke and mortality.
The findings were consistent across trials and were independent of age, sex, and type of supplement.
Although the increase in risk is modest, the widespread use of calcium supplements means that even a small increase might translate into a large burden of disease in the population, warn the authors.
Previous studies have found no increased cardiovascular risks with higher dietary calcium intake, suggesting that the risks are restricted to supplements.
Given the modest benefits of calcium supplements on bone density and fracture prevention, a reassessment of the role of calcium supplements in osteoporosis management is warranted, they concluded.
The study has been published on bmj.com.