No One Knows What’s Actually In Red Yeast Rice Supplements

–Despite tighter FDA rules red yeast supplements may not contain the active ingredient– or far too much of it.

A new study offers fresh evidence that it is impossible for consumers (or their doctors) to know what they are getting when they buy dietary supplements. Dietary supplements have long been, at best, loosely regulated in the United States. Starting in 2007 the FDA introduced new manufacturing standards for dietary supplements, but it now appears that these efforts have not resulted in products that are more reliable than in the past.

Pieter Cohen (Cambridge Health Alliance), a leading researcher and expert on supplement safety, and colleagues tested 28 brands of red yeast rice supplements purchased at major retail chains in the U.S. to determine levels of the active ingredient monacolin K, which is identical to the prescription statin drug lovastatin. The paper was published in the European Journal of Preventive Cardiology.

Two of the 28 brands had no detectable levels of monacolin K. For the other 26 brands, monacolin K levels were wildly divergent, ranging from 0.09 to 5.48 mg per 1,200 mg of red yeast rice. This represents a 60-fold variation in quantity, and a 120-fold difference based on the manufacturers’ daily serving recommendations.

Cohen said that the results also suggest that six of the products— 21%— could receive warning letters from the FDA, since the dosage exceeded the 4-mg/day limit established by the FDA.

“Red yeast rice is an excellent case study because it contains an ingredient identical to the prescription drug lovastatin,” said Cohen in an interview. “We found that there was no improvement in consistency or strength of red yeast rice supplements in respect to monacolin K content (a.k.a. lovastatin) after the FDA’s current good manufacturing standards were introduced.”

The study dovetails with one published in January that found an adverse effect profile for red yeast rice similar to that of statins: muscle pain, gastrointestinal reactions and one case of rhabdomyolysis.

Former FDA Commissioner Rob Califf (Duke University) said that “the FDA has severe legal and resource limitations when it comes to dietary supplements. Unless our society decides to prioritize regulation to produce high quality dietary supplements and data to demonstrate risks and benefits, buyers should be aware of the lack of evidence of benefit and the potential for this kind of variability in the product itself.”

“Even with certain safety and manufacturing regulations, individuals taking supplements never really know what exactly they are taking, how much they are taking, and — though not addressed in this study — what else is in the products that could be harmful,” said James Stein (University of Wisconsin). “Regulations may need to be tightened and until then, we should remember that supplements are not a substitute for real food and real medications.”

“The findings are a strong argument for tighter regulation of dietary supplements with regard to safety of key ingredients,” said Joshua Sharfstein (Johns Hopkins), a former deputy commissioner of the FDA. “Consumers deserve to know accurate information about what is in their supplements.”

Cohen said that red yeast rice is a good test case because it is one of the few supplements with a single known active ingredient. For other supplements “we often see variability in the ingredients but we don’t know if it has an effect on human health. But in this case we can say it is real and it will have an effect on human health.”

In his interview Cohen said that the new FDA guidelines are supposed to “ensure the strength and composition of products, but the fact is these guidelines don’t do it.” In fact, most supplements are not manufactured as they were by tradition but are now purchased in bulk from wholesalers in China and other countries.

“There’s no way the consumer can know what they are getting,” said Cohen. “The consumer can look at what’s on the label, which includes the amount, by milligram, of red yeast rice. This implies to the consumer a certain amount of goodness, but in reality this is meaningless.”


  1. Oh hang on, lovastatin and the others produced by drug companies have no side effects and that’s official, they are all nocebo/psychiatric in origin. Yet lovastatin in supplements DOES cause side effects. Whoops!

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