Calcium supplements, commonly taken by older adults to ward off osteoporosis, may increase the risk of heart attack. An international team of researchers examined data from 11 studies covering around 12,000 people who took calcium supplements without vitamin D. In all of the studies, people older than 40 years took supplements with calcium doses of 500 mg or higher daily. Compared with those who took a placebo, people who took calcium had a 31% higher risk of heart attack. There were also slightly higher, nonsignificant increases in the risk of stroke and death.

The increase in cardiovascular risk is modest, but "the widespread use of calcium supplements means that even a small increase in incidence of cardiovascular disease could translate into a large burden of disease in the population," write the authors. Although many people take calcium supplements to prevent osteoporosis, these supplements only marginally reduce the risk of bone fractures-by about 10%. "Maintaining a healthy weight, being physically active, not smoking, and having bone density measured are other important aspects of osteoporosis management," author Ian R. Reid told AJN.

Dee Sandquist, a spokesperson for the American Dietetic Association, advises people taking calcium supplements to add vitamin D to their regimens because other studies show no risk of heart problems when calcium and vitamin D are combined.-Carol Potera