Red yeast rice contains naturally-occurring substances called monacolins. Monocolins, particularly one called lovastatin, is believed to be converted in the body to a substance that inhibits HMG-CoA reductase, an enzyme that triggers cholesterol production. This is the way the popular statin drugs work. Because of this action, red yeast rice products containing a higher concentration of monocolins have been developed and marketed as a natural product to lower cholesterol. The problem is that the primary ingredient in these supplements, lovastatin, is also the active pharmaceutical ingredient in prescription drugs for high cholesterol such as Mevacor. In fact, lovastatin was originally derived from another type of red yeast called Monascus ruber. When the FDA discovered that red yeast rice contained a substance found in prescription drugs, it banned red yeast rice products containing lovastatin. In August, 2007, the FDA issued a warning that several red yeast rice products still contained lovastatin. The manufacturers of these products have since recalled these products. Yet studies by UCLA Medical have shown that the Red Yeast products on the market today are still effective in lowering LDL levels.
About.com, Oct 18, 2010