Key ingredient in red yeast rice supplements varies dramatically

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Have you considered taking a red yeast rice supplement to "naturally" lower your cholesterol, either instead of or in addition to a prescription statin? Think again. These popular over-the-counter supplements contain an ingredient identical to the one found in the prescription drug lovastatin (Mevacor) — but in completely unpredictable amounts, a new study finds.

Researchers tested 28 different brands of red yeast rice from four mainstream retailers (GNC, Walgreens, Walmart, and Whole Foods). Two brands contained no detectable levels of the active ingredient, called monacolin K. In the other 26, monacolin K levels ranged from a trace to nearly 5.5 milligrams (mg) per 1,200 mg of red yeast rice. For some brands, the recommended daily serving overlapped with the dosage of prescription lovastatin.

Prior studies of red yeast rice supplements also found wide variations in monacolin K levels. But this new analysis was done after the FDA had fully implemented new manufacturing standards for dietary supplements that began a decade ago. The standards, which were intended to ensure the composition and strength of supplements, don't appear to have made a difference, at least for this product. The study was published online June 23, 2017, by the European Journal of Preventive Cardiology.