AUCKLAND, New Zealand, Jan. 16 (UPI) -- Calcium supplements may increase the risk of heart attack in healthy post-menopausal women, a University of Auckland study found.

First author Mark J. Bolland said while calcium supplementation is commonly prescribed to post-menopausal women to maintain bone health, there is little research on calcium and vascular disease.

The study involved 1,471 healthy post-menopausal women age 55 years or older who had previously taken part in a study to assess the effects of calcium on bone density and fracture rates.

The women were randomly allocated either a daily calcium supplement or placebo. Dietary calcium intake was assessed and women were seen every six months during a five-year period.

The study, published in the British Medical Journal, found heart attacks were more commonly reported in the calcium group. Stroke or sudden death was also more common in this group.

The findings are not conclusive, but suggest that high calcium intake might have an adverse effect on vascular health. If confirmed by other studies, the effect could outweigh beneficial effects of calcium on bone, the researchers said.

In the meantime, the potentially detrimental effect should be balanced against the likely benefits of calcium on bone, particularly in elderly women, the researchers said.