(Health.com) -- Bottles of the popular cholesterol-lowering supplement red yeast rice almost always list 600 milligrams of rice as the sole ingredient. But different brands of capsules contain widely varying amounts of the active ingredient that fights cholesterol, a new study suggests.
The active ingredients in red yeast rice, a type of fermented rice, are compounds known as monacolins that slow the production of cholesterol in the liver. One compound, monacolin K, is a naturally occurring version of the prescription drug lovastatin.
The study was conducted by researchers from ConsumerLab.com, who analyzed the ingredients of 12 red yeast rice products that were bought in stores or ordered over the Internet. (ConsumerLab.com is a company that independently tests dietary supplements and other nutritional products.)
Although each brand of capsule was said to contain 600 milligrams of red yeast rice, the level of monacolins ranged across brands, from a low of 0.31 milligrams to a high of 11.15 milligrams per capsule -- a 100-fold difference, the researchers found. Levels of monacolin K varied by a similar amount.
Although the brands were not named in the study, previously published ConsumerLab.com data indicate that they included Nature's Plus, Solaray, and Walgreens.
The fact that consumers who take red yeast rice capsules don't know exactly how much active ingredient they're ingesting could be a problem, the researchers say.
"Red yeast rice is certainly effective at lowering cholesterol and may have an important role in people who can't take statins or [who] refuse to take statins, but there's a lot of variability and potentially dangerous side effects," says the lead author of the study, Dr. Ram Gordon, M.D., a cardiologist at Chestnut Hill Hospital, in Philadelphia, and Abington Memorial Hospital, in Abington, Pennsylvania. "Until there's better regulation and oversight, we all have to be very cautious in recommending it to patients."
What's more, one-third of the products contained small but detectable amounts of citrinin, a toxin that can cause kidney failure in animals, according to the study, which appears in the Archives of Internal Medicine. The risk citrinin poses to humans isn't clear.
Dr. Stephen Kopecky, M.D., a cardiologist at the Mayo Clinic, in Rochester, Minnesota, says that the variability seen in the study is "nothing new." He generally discourages patients from taking red yeast rice and other cholesterol-lowering supplements and instead recommends low doses of lovastatin.
"You can get that for about $10 for three months at many of the big pharmacies," he says. "It's the same substance but a more exact amount."
The lack of standardization across brands is found throughout the supplements industry, not just in red yeast rice products, says Kate Ulbricht, the editor of the Journal of Dietary Supplements and a co-founder of the Natural Standard Research Collaboration, an independent research group focused on complementary and alternative treatments.
"It's happened across products," Ulbricht says. Multiple lab tests have found that supplements "contain sawdust or 99 percent water," she adds.
Although they did not investigate variations within brands of red yeast rice in this study, Gordon and his colleagues suggest that monacolin levels may vary even across batches of the same brand.
Red yeast rice differs from many dietary supplements in that one of its active ingredients is a drug regulated by the Food and Drug Administration (FDA). Numerous red yeast rice products have attracted the attention of the FDA because federal law prohibits companies from marketing dietary supplements that contain any ingredient previously approved as a drug.
In 1998, the FDA tried to ban one red yeast rice product, Cholestin, after claiming it constituted an unapproved drug, and the agency has sent warning letters to several other manufacturers.
Due to the laws surrounding the marketing of red yeast rice, manufacturers aren't allowed to list the amount of monacolins their products contain, says Andrew Shao, Ph.D., the senior vice president of scientific and regulatory affairs at the Council for Responsible Nutrition, a trade association that represents the supplements industry.
"Red yeast rice supplements cannot claim the amount of lovastatin on their label," Shao says.
Industry-wide manufacturing practices introduced in 2007 may already have minimized the variability found in the study, Shao says. (All but two of the products tested in the study were analyzed in March 2008.) Still, he acknowledges the potential risk caused by uncertain amounts of monacolins and urges consumers to talk to their doctors before taking red yeast rice.
Research suggests that red yeast rice may be a viable alternative to prescription statins such as Zocor and Lipitor. A 2008 study led by one of Gordon's co-authors found that red yeast rice, when accompanied by fish oil supplements and lifestyle changes, lowered LDL ("bad") cholesterol as effectively as Zocor.
Red yeast rice isn't the only nonprescription alternative for people with high cholesterol who can't take a statin (or don't want to), Kopecky says. A combination of oat bran, plant sterols and stanols (compounds found in supplements and in products such as margarine), and psyllium seed (found in products such as Metamucil) can also be effective, he says.
"Exercising regularly, cutting down on calories, losing seven or eight or 10 pounds, and taking the three supplements is going to do more for prolonging life than taking a pill," Kopecky says.
Copyright Health Magazine 2011