New research suggests that calcium supplements may increase the risk of heart attack in healthy postmenopausal women. Calcium supplementation is commonly prescribed to postmenopausal women to maintain bone health, and some data suggest that it might protect against vascular disease by lowering levels of bad cholesterol in the blood. But evidence for this theory is lacking, so researchers investigated the effect of calcium supplementation on heart attack (myocardial infarction), stroke, and sudden death.