Bile acids

Bile acids are steroid acids found predominantly in the bile of mammals. They are produced in the liver by the oxidation of cholesterol, and are stored in gallbladder and secreted into the intestine in the form of salts. They act as surfactants, emulsifying lipids and assisting with their absorption and digestion.

Synthesis of bile acids is a major consumer of cholesterol. The body synthetizes about 800 mg of cholesterol per day and about half of that is used for bile acid synthesis. In total about 20-30 grams of bile acids are secreted into the intestine daily; about 90% of excreted bile acids are reabsorbed and recycled.

The chemical distinctions between different bile acids are minute, depending only on the presence or absence of hydroxyl groups on positions 3, 7, and 12.

In humans, the most important bile acids are cholic acid and chenodeoxycholic acid, and their conjugates with taurine and glycine (glycocholate and taurocholate). Some mammals synthesize predominantly deoxycholic acid.

The principal bile acids are:
 * Cholic acid
 * Chenodeoxycholic acid
 * Deoxycholic acid
 * Taurocholic acid
 * Glycocholic acid