A Chinese extract has shown it may reduce the risk of a repeat heart attack in heart patients by almost 50 per cent, new research shows.

A partially purified extract of Chinese red yeast rice, called Xuezhikang (XZK), lowered the risk of a repeat heart attack by 45 per cent, death from heart disease by 30 per cent and total premature mortality by 33 per cent.

"Treatment with XZK during a four-year period appeared to have prevented 47 major [17 fatal, 30 nonfatal] coronary events," the study reads.

The extract also lowered total cholesterol levels by 13 per cent, low-density lipoprotein (LDL) cholesterol (bad cholesterol) by 20 per cent but raised high-density lipoprotein cholesterol (good cholesterol) levels by 4.2 per cent, which reduces the risk of a heart attack .

"It's very exciting because this is a natural product and had very few adverse side effects including no abnormal blood changes," David Capuzzi, director of the cardiovascular disease prevention program at Jefferson's Myrna Brind Center of Integrative Medicine in Philadelphia, said in a release.

"People in the Far East have been taking Chinese red yeast rice as food for thousands of years, but no one has ever studied it clinically in a double-blind manner with a purified product against a placebo group until now and we are pleased with the results."

The randomized, double-blind study involving 5,000 Chinese patients was carried out between May 1996 and December 2003. The patients, ranging in age from 18 to 70, had suffered previous heart attacks. While one group took 300 mg capsules of the extract, the control group was given a placebo.

Researchers caution that the supplement available over the counter in the U.S. is not the same as the one used in the study, and its effectiveness is not known.

The findings are published in the June 15th issue of the American Journal of Cardiology.

Chinese medical practitioners have used extracts of red yeast rice for centuries to treat circulatory problems, according to the study. In fact, because the extract reduces lipid levels in the blood, it has formed the basis of statin drugs, such as Lovastatin in the U.S.

"If further testing and study prove true, my hope is that XZK becomes an important therapeutic agent to treat cardiovascular disorders and in the prevention of disease, whether someone has had a heart attack or not," said Capuzzi.

Scientists aren't sure how the extract works and plan further study.