Variability in strength of red yeast rice supplements purchased from mainstream retailers

Abstract

The United States Food and Drug Administration (FDA) has introduced manufacturing standards for dietary supple- ments, including red yeast rice, to assure their identity, purity, strength, and composition. One supplement commonly used to self-treat high cholesterol, red yeast rice, may contain monacolin K, an ingredient identical to prescription lovastatin. We examined whether FDA’s manufacturing standards led to standard concentrations of the statin monacolin K in red yeast rice supplements. We analyzed 28 brands of red yeast rice supplements by ultra-high performance liquid chromatography-diode array detector-quadrupole time-of-flight mass spectrometry for monacolin K content. Monacolin K was not detected in two brands. In the 26 brands that contained monacolin K, the quantity ranged more than 60-fold from 0.09 to 5.48 mg per 1200 mg of red yeast rice. Following the manufacturers’ recommendations for daily servings, the quantity of monacolin K consumed per day would range more than 120-fold from 0.09 to 10.94 mg. Despite FDA manufacturing standards, strength and composition of red yeast rice supplements sold at mainstream retail stores in the United States remains unpredictable.