The bile acid theory in the pathogenesis of AAD. Dihydroxybile acids appear in italics and bile acids notably soluble at the 6–8 pH of the human colon appear in bold. Dihydroxy bile acids are laxative in vitro but must be soluble to exert a laxative effect in vivo. Thus, only chenodeoxycholic acid is notably laxative in vivo in the human colon and is supposed to accumulate under antibiotics reducing the numberof 7a-dehydroxylating bacteria.
Antibiotic-associated diarrhoea 341
theory could perhaps revive if epidemiological studies show that fresh stools from