Reid suggested that high doses of calcium might damage the walls of blood vessels, which leads to heart attacks.
"Most people should not be taking calcium supplements," he said. "You should get the calcium you need from your diet rather than taking supplements."
In terms of reducing fractures, Reid said that based on his study, which appeared online in the journal BMJ in July 2010, calcium supplements may reduce fractures 10 percent, but can increase the risk of heart attacks 25 percent.
He said his study showed that if 1,000 people are given calcium for five years, there will be 26 fractures prevented but there will also be 14 heart attacks, 10 strokes and 13 deaths.
Commenting on the new study, Dr. Gregg Fonarow, a professor of cardiology at the University of California, Los Angeles, added that "it has been hypothesized that abrupt changes in concentrations of calcium in the blood with calcium supplementation might be contributing to adverse cardiovascular effects."
So, he stated, "while further studies are needed, calcium supplements should be used only in those where the potential benefits outweigh the potential risks."
While the study found an association between calcium intake and heart attacks, it did not prove a cause-and-effect relationship.
For more about calcium supplements, visit the U.S. National Institutes of Health.
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