Calcium supplements, often prescribed to post-menopausal women to help strengthen their bones, may boost the risk of heart problems and stroke, according to a paper published on Wednesday by the British Medical Journal.

Previous studies have suggested the opposite effect – that high calcium intake boosts vascular health in post-menopausal women by increasing the proportion of “good” cholesterol in the blood over “bad” cholesterol.

The team, led by Ian Reid, caution that the association they see between calcium boosters and sudden heart problems is not conclusive and needs to be explored further.