The results of one of the first two U.S. studies of the substance, called Cholestin, were presented Thursday in Orlando at a medical conference sponsored by the American Heart Association.
It showed that people with mildly elevated levels could drop their cholesterol about 35 points by taking four capsules of Cholestin a day.
Cholestin is made from red yeast that has been fermented on rice. Its chief ingredient is a naturally occurring form of Lovastatin, a prescription cholesterol-lowering medicine.
Cholestin's introduction in 1997 blurred the already fuzzy line between food supplements, which can be sold without a prescription, and drugs that require approval from Food and Drug Administration.
The FDA declared Cholestin to be an unapproved drug and attempted to block its sale. Cholestin's manufacturer, Pharmanex Inc. of Simi Valley, Calif., sued and won.
Last month, a federal judge in Salt Lake City ruled that Cholestin fits the definition of a dietary supplement and can stay on the market. The FDA has not said whether it will appeal.
Until now, all of the data on Cholestin's health effects have come from China, where the rice extract has been used for centuries as a spice for food.
Last month, Dr. David Heber of the University of California at Los Angeles published a report on the substance in the American Journal of Clinical Nutrition. 83 volunteers took Cholestin for eight weeks and lowered their blood cholesterol an average of 17 percent. The latest study was directed by Dr. James Rippe of Tufts University in Boston and found similar results.
Pharmanex financed both studies, and both Heber and Rippe are members of the company's medical advisory board.
"This is a promising new development worthy of further research," said Dr. Thomas A. Pearson of the University of Rochester, speaking for the heart association.
However, he cautioned against going on Cholestin without getting a doctor's advice. "This should be integrated into the overall care plan," he said.
Lovastatin, sold by Merck Inc. as Mevacor, was the first of a powerful new class of cholesterol-lowering medicines known as statins. The smallest Lovastatin pill on the market is 10 milligrams, while a daily four-pill regimen of Cholestin adds up to 5 milligrams of Lovastatin.
Cholestin can be bought without a prescription, but the price is similar to Mevacor. A month's supply costs about $30.
Pharmanex's sponsorship of scientific research to back up its health claims is relatively unusual among supplement makers. Another study nearing completion will look at the effects of Cholestin when eaten in a twice-daily power bar.