Red Yeast Rice is a unique natural product native to China, that's been used in Asian traditional medical systems since approximately 800 A.D. Produced by fermenting red yeast (Monascus purpureus) with white rice. Red Yeast Rice is commonly used in cooking applications to enhance the color and flavor of foods. Peking Duck is an example of the coloration and flavor imparted by Red Yeast Rice. NOW® Red Yeast Rice Extract is carefully produced to avoid the presence of citrinin, a sometimes toxic by-product of the fermentation process.