Bile acid and bile salt metabolism

In a healthy adult human, about 500 mg of cholesterol is converted to bile salts daily. Newly synthesized bile salts are secreted into the bile and released into the small intestine where they emulsify dietary fats. About 95% of the bile salts in the intestine are recovered and returned to the liver. 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 extrahepatic cholesterol homeostasis.

Summary from Reactome (R-HSA-194068), read 2026-09-23.