The same researchers who said red yeast rice can lower LDL cholesterol are now advising the millions of people who use this alternative therapy to be careful.

In a study published Oct. 25 in Archives of Internal Medicine, the authors said they found wide variations in the amounts of monacolins, the active ingredients identical to cholesterol-inhibiting lovastatin, in the red yeast rice samples they tested.  High levels of statins can cause muscle and liver damage.

The researchers, who analyzed 12 commercial formulations of red yeast rice, also said four of the samples they tested contained the fungus citrinin, which has been shown to cause kidney failure in animals.

Red yeast rice is made by inoculating water-soaked or steamed rice with the yeast strain Monascus purpureus, then leaving the mix to ferment at room temperature for several days.  The cultured rice turns bright red, and is typically sold as a dried grain, cooked and mashed into paste or dried and pulverized into powder.

The U.S. Food and Drug Admistration has unsuccessfully tried to regulate red yeast rice as a drug, and most of the brands available in the U.S. avoid FDA restrictions by not making any health claims.

While the study’s authors acknowledge the supplement’s potential as a cholesterol-reducing agent, they suggest a need for standardization of red yeast rice products and product labeling.  The title of the study  is, “Buyer Beware.”