Guggulsterone is a plant steroid found in the resin of the guggul plant, Commiphora mukul. Guggulsterone can exist as either of two stereoisomers, E-guggulsterone and Z-guggulsterone. In humans, it acts as an antagonist of the farnesoid X receptor, which was once believed to result in decreased cholesterol synthesis in the liver. Several studies have been published that indicate no overall reduction in total cholesterol occurs using various dosages of guggulsterone, and levels of low-density lipoprotein ("bad cholesterol") increased in many people.[1][2] Nevertheless, guggulsterone is an ingredient in many nutritional supplements. Guggulsterone (GS) is the active substance in guggulipid, an extract of the guggul tree, Commiphora mukul, used to treat a variety of disorders in humans, including dyslipidemia, obesity, and inflammation.