In a healthy adult human, about 500 mg of cholesterol is converted to bile salts daily (Russell 2003). The major pathway for bile salt synthesis in the liver begins with the conversion of cholesterol to 7alpha-hydroxycholesterol. Bile salt synthesis can also begin with the synthesis of an oxysterol - 24-hydroxycholesterol or 27-hydroxycholesterol. In the body, the initial steps of these two pathways occur in extrahepatic tissues, generating intermediates that are transported to the liver and converted to bile salts via the 7alpha-hydroxycholesterol pathway. These extrahepatic pathways contribute little to the total synthesis of bile salts, but are thought to play important roles in cholesterol homeostasis (Javitt 2002).