They found the total level of monacolins, the active ingredients, varied from 0.31 milligrams to 11.15 milligrams per capsule. Four of the formulations also contained citrinin, a toxin from fungus that is harmful to the kidneys.
“Red yeast rice has been used for centuries for its medicinal properties and is an increasingly popular alternative lipid-lowering therapy that may benefit patients with a history of coronary disease who cannot take statins, subjects who refuse statins or who prefer a ‘natural’ approach to pharmacotherapy," write researcher Ram Y. Gordon, MD, of the University of Pennsylvania Health System, and colleagues in the Archives of Internal Medicine.
"However, our study found dramatic variability of monacolin levels in commercial products and the presence of citrinin in one-third of formulations," they write. "Further oversight and standardization of the production and labeling of red yeast rice products may address some of the concerns raised in this study."
Red Yeast Rice: Buyer Beware
Chinese red yeast rice, also known as hong qu, is created by culturing a yeast (Monascus purpureus) on rice. The process produces several compounds called monacolins, such as monacolin K, which is marketed in its purified form as the drug lovastatin.
Researchers say several studies have shown certain formulations of red yeast rice can reduce LDL “bad cholesterol,” largely related to the effects of the monacolins in the supplement.
Americans spent an estimated $20 million on red rice yeast supplements in 2008. But to avoid being regulated as an unapproved drug by the FDA, researchers say manufacturers do not standardize or disclose the levels of monacolin K or other monacolins in their supplements.
In the study, researchers found not only did total monacolin levels vary widely in the 12 products analyzed, but levels of monacolin K or lovastatin ranged from 0.10 milligrams to 10.09 milligrams per capsule.
In addition, four of the products contained elevated levels of the toxin citrinin.