Red yeast rice is rice that has been fermented using Monascus purpureus, a red yeast. For more than a thousand years, the Chinese have used red yeast rice for medicinal purposes, including treatment of indigestion, poor blood circulation, and diarrhea. They have also used it as a food preservative and a food coloring, and in rice wine.
Substances in red yeast rice called monacolins have the ability to inhibit the synthesis of cholesterol, and thus extracts of red yeast rice have been available as a natural supplement to lower cholesterol. One of the monacolins, called monacolin K, inhibits HMG-CoA reductase, an enzyme that has a major role in the production of cholesterol in the liver. Another HMG-CoA reductase inhibitor is the pharmaceutical drug lovastatin (Mevacor®), a popular statin medication.
The FDA has ruled that it is not legal to sell supplements of red yeast rice in the United States that contain more than trace amounts of cholesterol-lowering substances. According to the FDA, it has banned more potent red yeast rice supplements from the US market because statins are associated with kidney and muscle damage when they are used alone or along with other medications. Therefore individuals could risk injury by taking red yeast rice supplements. The FDA also views products that contain red yeast rice with high levels of cholesterol-reducing substances to be unapproved drugs, and marketing them violate the Federal Food, Drug, and Cosmetic Act.
Red yeast rice supplements that contain higher amounts of monacolin K are available outside the United States. Scientists have conducted studies on these products (Cholestin, Xuezhikang, Zhitai) and uncovered promising results. The studies have found that the supplement lowered total cholesterol by an average of 10 to 30 percent, reduced LDL cholesterol by an average of 10 to 20 percent, lowered triglycerides by an average of 15 to 25 percent, and increased HDL by an average of 7 to 15 percent. (Liu 2006)
Researchers at the University of California, Los Angeles, Center for Human Nutrition studied Cholestin in a 12-week, double-blind, placebo-controlled trial that included 83 adults who had borderline-high to moderately high cholesterol. The study used Cholestin that had higher levels of red yeast rice than is currently allowed. These scientists found that red yeast rice reduced total cholesterol, LDL cholesterol, and triglycerides, but had no effect on HDL cholesterol. (Havel 1999)
The red yeast rice supplements available in the United States contain very low concentrations of active ingredient and thus are much less likely to cause side effects. However, some products may contain high levels of a toxic substance called citrinic acid. More potent red yeast rice supplements available from outside the United States may cause dizziness and gastrointestinal discomfort. Do not take red yeast rice supplements without first consulting your physician.
Havel RJ. Dietary supplement or drug? The case of cholestin. Am J Clin Nutr 1999 Feb; 69(2): 175-76
Liu J et al. Chinese red yeast rice (Monascus purpureus) for primary hyperlipidemia: a meta-analysis of randomized controlled trials. Chin Med 2006 Nov 23; 1:4