Abnormal metabolism of secondary bile acids in patients with cirrhosis1

The main bile acids in human bile are cholic, chenodeoxycholic, and deoxycholic with a mean ratio of 1.1:1.0:0-6 (Sjovall, 1960). Cholic and chenodeoxycholic acid are primary bile acids synthesized from cholesterol in the liver (Bergstrom, Danielsson, and Samuelsson, 1960). These bile acids are not interconvertible. The secondary bile acids, deoxycholic and lithocholic, are products formed by the action of intestinal microbial enzymes. The removal of the hydroxyl group at C-7 position of cholic and chenodeoxycholic acid is effected mainly by anaerobic intestinal microorganisms resulting in the formation of deoxycholic and lithocholic acids respectively (Norman and Bergman, 1960; Bergstrom et al, 1960; Hill and Drasar, 1968). Deoxycholic acid occurs in varying amounts in the bile of several species and is the major bile acid found in human faeces. Lithocholic acid is poorly absorbed by the colon and is therefore present in small amounts in human bile. Following the dehydroxylation of the primary bile acids, the secondary bile acids enter the enterohepatic cycle and are incorporated into the total bile salt pool. In man and the rabbit, the secondary bile acids are not rehydroxylated in the liver (Ekdahl and Sjovall, 1955; Lindstedt and Sjovall, 1957). In the light of our present knowledge, the presence of the secondary bile acids in human bile is a reflection of normal intestinal flora and