Potential heart risk from calcium supplements

Calcium supplements may slightly raise the risk of heart attack, death from heart disease, and stroke for women, according to controversial new findings.

The conclusions, published today, are disputed by many evidence who say the case is not yet proved.

These supplements, with or without vitamin D, are widely used in an effort to prevent or treat osteoporosis.

Researchers at the University of Auckland, New Zealand, looked at the potential heart risk flagged up in recent studies. They used figures from 36,282 postmenopausal women in the Women’s Health Initiative study. Half took 1g calcium and 400 IU vitamin D daily, and half placebo, for seven years. Over half were already taking calcium supplements.

Analysis showed a link between supplement use and cardiovascular events – heart attack, coronary revascularisation, death from coronary heart disease, or stroke.

The rate was raised by 13 to 22 per cent in women who started taking supplements. Risk was not increased in those already taking supplements before the study began.

Next, the researchers looked at results from eight other trials and found that calcium and vitamin D increased the risk of heart attack by 24 per cent, and combined risk of heart attack or stroke by 15 per cent.

Writing for the British Medical Journal, they say: "Calcium supplements with or without vitamin D modestly increase the risk of cardiovascular events, especially myocardial infarction [heart attack], a finding obscured in the WHI [Women’s Health Initiative] study by the widespread use of personal calcium supplements."

They recommend that the role of calcium supplements in osteoporosis management is reassessed.

Professor Bo Abrahamsen of Gentofte Hospital, Copenhagen, Denmark, states in an editorial that there is "insufficient evidence is available to support or refute the association".

Cathy Ross of the British Heart Foundation added: "It’s very important further studies are carried out. There is still not enough evidence to confirm the association."

Bolland, M. J. et al. Calcium supplements with or without vitamin D and risk of cardiovascular events: reanalysis of the Women’s Health Initiative limited access dataset and meta-analysis. The British Medical Journal, 2011;342:d2040.

Abrahamsen, B. and Sahota, O. Do calcium plus vitamin D supplements increase cardiovascular risk? The British Medical Journal, 2011;342:d2080.