The role of colon anaerobes in the metabolism of bile acids and steroids, and its relation to colon cancer.

The principle enzymes in the metabolism of both the substituent groups and the nucleus of the bile acids and of cholesterol are reviewed, together with their possible relevence to the etiology of large bowel cancer. Since the incidence of the disease appears to be related to the bile acid concentration and the activity of the 7-dehydroxylase and the delta4-dehydrogenase enzymes, the study of bile acids with a 4,6-dien-3-one structure is strongly recommended.