Guggulsterone is a plant sterol foun in the resin of the guggul plant, Commiphora mukul. Molecules of guggulsterone have two stereoisomers, E-guggulsterone and Z-guggulsterone. In humans, it acts as an antagonist of the farnesoid X receptor, which was earlier believed to result in decreased cholesterol synthesis in the liver. However, several studies have been published that indicate no overall reduction in total cholesterol occurs using various dosages and levels of LDL(low density fraction) increase in many people. Guggulsterone is an ingredient in many nutritional supplements.