TISSUE HYPERTROPHY AND EPITHELIAL PROLIFERATION RATE IN THE GUT OF RATS FED ON BREAD AND HARICOT BEANS (PHASEOLUS-VULGARIS)

The present study was designed to test the hypothesis that increasing short-chain fatty acid (SCFA) production in the large bowel increases gut epithelial proliferation rate (EPR), Two experiments were carried out in which rats mere fed on bread (wholemeal or white)-based diets c ontaining graded amounts of cooked haricot (Phaseolus vulgar is) beans ; the latter are a rich source of fermentable carbohydrates, Consumpti on of beans was associated with several-fold increases in SCFA product ion with the greatest relative increase being for butyrate. Despite th e very large increase in SCFA production, there was no evidence that t his had any effect on EPR in the duodenum, Where the basal diet contai ned wholemeal bread (Expt 1) there was no effect of enhanced SCFA supp ly on EPR in either the caecum or colon, but with the white bread-base d diet (Expt 2) adding beans produced increments in both SCFA supply a nd EPR in the caecum, Evidence that SCFA are responsible for enhanced EPR above normal levels is not convincing, In those instances where en hanced SCFA supply is associated with increased EPR, the increase may be (1) from a hypoproliferative state towards normal, (2) a transient phenomenon accompanying tissue hypertrophy or (3) a homeostatic respon se to increased cell loss by cell sloughing or apoptosis, It is not li kely that there is any direct link with risk of colon cancer.