COLONIC FERMENTATION OF COMPLEX CARBOHYDRATES IN PATIENTS WITH FAMILIAL ADENOMATOUS POLYPOSIS

Decreased production of butyric acid by colonic carbohydrate fermentat ion may predispose to colonic carcinogenesis, with the implicit assump tion that the decrease in faecal butyrate found predates the developme nt of the tumour. The influence of the genetic predisposition to colon ic tumours and the presence of colonic polyps on in vitro fermentation of carbohydrates was examined. Stool samples from 11 normal controls and 20 patients with familial adenomatous polyposis (FAP) were incubat ed anaerobically with a range of carbohydrates. Fermentation patterns were similar for glucose and raffinose. These sugars produced differen t short chain fatty acid (SCFA) patterns from the two polysaccharides, starch and arabinogalactan, which differed one from the other. The FA P gene carriers with polyps produced less butyrate than normal control s (p<0.005) and gene carriers without polyps (p<0.05). There were corr esponding decreases in the molar ratios of butyrate. Gene carriers wit hout polyps produced less absolute amounts of acetate than normal cont rols (p<0.05) and slightly less total SCFAs (p<0.05) but were otherwis e not significantly different. The decreased production of butyrate no ted by other workers may be secondary to the tumours rather than a con tributory cause.