Red yeast rice is a substance extracted from rice that has been fermented with a type of yeast called Monascus purpureus. It is very popular in Asian countries, as it has been used for centuries in Chinese medicine "to strengthen the spleen and to improve digestion and poor blood circulation". Red yeast tablets have also been recommended as a natural alternative to help regulate cholesterol levels. Red yeast rice naturally contains several ingredients that may help to control cholesterol levels. Active compounds called monacolins, most importantly monacolin K, are naturally-occurring HMG-CoA inhibitors; which means that they inhibit a major enzyme involved in cholesterol synthesis in the liver. Monacolin K, also known as lovastatin, works by blocking the production of cholesterol to reduce the low-density lipoprotein (LDL) often called "bad cholesterol" and plasma triglycerides. Red yeast rice also contains natural sterols (beta-sitosterol and campesterol), that help to block cholesterol absorption in the intestines, isoflavones and monounsaturated fatty acids, or "healthy fats". HealthAid Red Yeast Rice tablets provide 10mg of monacolin K, which contributes to the maintenance of normal blood cholesterol levels. By hindering cholesterol production as well as reducing cholesterol absorption in the intestines, red yeast rice tablets may help slow down a process known as atherosclerosis, a pathological result of plaque formation in the arteries that precedes most cardiovascular ailments, including high blood pressure, stroke and heart attack.