Gut bacteria and their metabolic activities in familiar polyposis.

Earlier work had suggested that patients with large-bowel cancer can be characterized by carriage of clostridia capable of dehydrogenating the nucleus of steroids and by high faecal bile-acid concentrations. Familial polyposis is an inherited disease which untreated, will progress to cancer of the large bowel, and those affected might be expected to have these metabolic characteristics. However, enviromental factors seem to play no part in polyposis. Investigation of as yet unaffected children of known polyposis patients revealed that the gut flora of half of them did not degrade cholesterol in vivo andnor did flora from patients in whom polyposis had already been diagnosed. The reason for this is unknown, but if the same patients develop polyposis (i.e., they carry the abnormal gene) we would have a simple diagnostic test which could replace the continuing follow-up now required for the siblings and children of patients with polyposis.