The resin of the Commiphora mukul tree has been used in Ayurvedic medicine for more than 2000 years to treat a variety of ailments. Studies in both animal models and humans have shown that this resin, termed gum guggul, can decrease elevated lipid levels. The stereoisomers E- and Z-guggulsterone have been identified as the active agents in this resin. Recent studies have shown that these compounds are antagonist ligands for the bile acid receptor farnesoid X receptor (FXR), which is an important regulator of cholesterol homeostasis. It is likely that this effect accounts for the hypolipidemic activity of these phytosteroids.