Red yeast rice is produced by fermenting rice with a type of yeast called Monascus purpureaus. Because of its unique, reddish-purple color, it is used as a natural dye for a wide variety of foods, including red rice vinegar, Peking duck, pickled tofu and fish sauce. Red yeast rice is also used to make sake, Korean rice wine and many types of Chinese wine.
In addition to its culinary role, red yeast rice has been used for hundreds of years in traditional Chinese medicine (TCM) as a mild treatment for indigestion, diarrhea and poor blood circulation.

Red yeast rice contains natural substances called monacolins, and one of these - monacolin K -obstructs HMG-CoA reductase, the enzyme involved in the production of cholesterol. As a result, many red yeast rice products have been marketed as natural, cholesterol-lowering remedies.

To date, there have been limited studies on red yeast rice that are well-designed. However, one study from the UCLA School of Medicine looked at the effects of red yeast rice on 83 subjects with high cholesterol. All subjects were placed on a controlled diet of 30% fat per day with less than 300 mg of cholesterol consumed. One group of the subjects received 2.4 daily grams of red yeast rice and the other group, a placebo.

After 12 weeks, there was a significant reduction of triglyceride levels and total LDL cholesterol in the red yeast rice group, as compared to the placebo subjects. However, HDL levels were unaffected.

Although it appears to work, one problem with some red yeast rice products is that a key ingredient called lovastatin is also an active ingredient found in prescription drugs for high cholesterol. Concerned that this product might also cause the same side effects as statin drugs (muscle pain, muscle damage and liver damage), the FDA banned all red yeast rice products containing lovastatin.

Because red yeast rice products can no longer contain this ingredient, it is uncertain whether they continue to have cholesterol-lowering effects, and there are concerns about quality. Levels of monacolins in the products can vary. Also, when not fermented correctly, red yeast rice can contain citrinin – a toxin that can cause kidney damage.
It is thought that new red yeast rice products are probably safe for most people when taken for three months or less, but there is no information regarding long-term use. Mild side effects can include stomach upset, heartburn, gas and dizziness. As always, before taking any kind of supplement, individuals should consult a health care provider.