Bile Acid Synthesis
Hepatic conversion of cholesterol to bile acids for lipid digestion and signaling.
Overview
Bile acid synthesis is the primary route for cholesterol elimination. The classic (neutral) pathway begins with CYP7A1 (cholesterol 7α-hydroxylase), the rate-limiting enzyme. Through multiple hydroxylation and side-chain cleavage steps, cholesterol is converted to primary bile acids (cholic acid and chenodeoxycholic acid), conjugated with glycine or taurine, and secreted into bile. In the intestine, gut bacteria convert primary bile acids to secondary bile acids (deoxycholic and lithocholic acid). Bile acids are efficiently recycled via enterohepatic circulation.
Cellular Location
Liver → Bile → Intestine → Portal vein → Liver (enterohepatic circulation)
Clinical Significance
Bile acid sequestrants lower cholesterol; FXR agonists (obeticholic acid) for NASH/PBC; gut microbiome-bile acid interactions affect metabolic health; gallstone formation involves bile acid imbalance.