Calcium supplements taken by many old women could be increasing the risk of a heart attack. This startling revelation has been made by research scholars in the British Medical Journal, which said people who took supplements were 30 per cent more likely to have a heart attack. The claim is made after studying data from eleven trials. The trials also suggest the medicines were not very effective in bone fractures. Almost three million people in UK are thought to have osteoporosis and many calcium pills to prevent fractures.