"The millions of people who take calcium supplements to strengthen aging bones and ward off osteoporosis may be putting themselves at increased risk of a heart attack, a new study has found.
Older people who take at least 500 milligrams of calcium daily--less than the amount in a typical one-a-day calcium pill--are 30 percent more likely to have a heart attack than those who take no calcium at all, the study estimates."
http://www.cnn.com/2010/HEALTH/07/29/calcium.supplements.up.heart.risk/index.html