Clinical studies show that red yeast rice supplements can dramatically lower LDL (“bad”) cholesterol, however, recent tests by ConsumerLab.com, White Plains, NY,
showed that products tested were as much as 500 times stronger than others, despite listing the same amount of red yeast rice on labels. U.S. sales of red yeast rice supplements were $41 million in 2012, according to Nutrition Business Journal.

ConsumerLab.com identified at least three products that provided the amounts of natural, cholesterol-lowering compounds (known as monacolins and lovastatins) proven to lower cholesterol levels in clinical trials. Meanwhile, several other products were found to contain only small amounts of these compounds, making them unlikely to have a significant effect on cholesterol. One popular brand was also discovered to contain citrinin, a potential kidney toxin, according to the report.

Among the eight products covered in the new report, three were the same as those tested in 2011 by ConsumerLab.com. However, the amounts of lovastatin compounds in these three products were found to be as much as 88% higher to 33% lower than in 2011—suggesting they may now be more, or less, effective, respectively, than before. ConsumerLab.com first tested red yeast rice supplements in 2008. Those results were subsequently published in a peer-reviewed article in Archives of Internal Medicine.

Labels on red yeast rice products generally do not disclose their lovastatin content due to concern that the supplement will be considered an unapproved drug by the FDA and removed from the market, since lovastatin is a prescription drug (originally sold as Mevacor). This makes it difficult for consumers and doctors to assess and compare red yeast rice supplements, although they remain widely used and can be effective.

Clinical studies of red yeast rice have shown reductions in LDL cholesterol of 18% to 42%, although each study has used a different red yeast rice preparation, providing from 4.9 mg to 27 mg of lovastatins per daily serving. The amounts of lovastatin compounds in products tested by ConsumerLab.com were discovered to range from only 0.05 mg to 25.1 mg per suggested daily serving—a 500-fold difference. In addition to containing lovastatin, red yeast rice contains a variety of other monacolin compounds that may act synergistically to lower LDL cholesterol while minimizing side effects normally associated with statin drugs. In clinical studies, these “other” monacolins account for about 20-25% of the total amount of monacolins. However, these levels were found to be as low as 2% in some of the products ConsumerLab.com tested.

“Red yeast rice can be one of the most effective supplements but one of the most difficult to safely choose,” said Tod Cooperman, MD, president of ConsumerLab.com. “If you use or are considering using red yeast rice, our new findings should be very helpful.”

The new report provides test results and comparisons.