Chinese food may be good for the heart. Researchers tested a common ingredient, Chinese red yeast rice, or rice fermented using a certain yeast species, and found that it reduced the risk of repeat heart attacks in people who have already had one.

The Chinese study, published on June 15 in The American Journal of Cardiology, tested 4,870 men and women who had had heart attacks within five years. They were randomly assigned to take 600 milligrams a day of yeast rice extract or a placebo. Neither researchers nor patients knew which patients received the active extract.

Over five years, those who took the extract reduced their relative risk of a coronary event by 45 percent. The risk of death from cardiovascular disease and from all causes in the extract group was about one-third that of the placebo group, and the need for an operation to improve blood supply to the heart was also reduced by about a third.

The rice is used as a food preservative, a spice and an ingredient in rice wine. Dr. David M. Capuzzi, the senior author and a professor of medicine at Thomas Jefferson University, emphasized that the finding did not apply to the red yeast extract sold in health food stores.

“This study,” Dr. Capuzzi said, “was done with a carefully constituted compound totally different from what is available over the counter.”