More than half of American adults take at least one dietary supplement, according to the CDC report.
Along with her calcium supplement, Hoffmann takes fish oil and a multivitamin.
But some experts argue that eating a well-balanced diet makes supplements, which escape regulation by the U.S. Food and Drug Administration, unnecessary. Dairy foods are a good source of calcium, as are dark, leafy greens like spinach. And some cereals, juices and soy milk brands are also enriched with calcium.
"Calcium intake through the diet did not apparently add to the risk, so it may be safer to take calcium through the diet," said Dr. Bart Clarke, associate professor of medicine at the Mayo Clinic in Rochester, Minn. "For now, [I] would recommend that patients discuss taking calcium supplementation with their doctor, and that they make sure their dietary calcium is adequate if they choose not to take calcium supplements."
Hoffman called the study findings "mildly scary," but said she'll continue taking calcium supplements anyway.
"I mean, there have been so many different studies that have proved to not make a darn bit of difference, and one more doesn't upset me that much," she said. "I think the thought of osteoporosis upsets me more than the heart attack risk does."
Dr. Harlan Krumholz, associate professor of medicine at Yale University School of Medicine in New Haven, Conn. said more research is needed to uncover the health risks, if any, tied to calcium supplements.
"The assumption should not be that they can't hurt and might help," Krumholz said. "We should all want strong evidence of benefit and assurance of safety before making choices to take supplements."