Effects of konjac glucomannan, inulin and cellulose on acute colonic responses to genotoxic azoxymethane

Mice were fed low-fibre, or that supplemented with soluble fibre (konjac glucomannan, KGM; inulin), or insoluble fibre (cellulose) to determine how these three fibres modulated the acute colonic responses to an azoxymethane (AOM) treatment. Results indicated that KGM and inulin exerted greater anti-genotoxic effects compared to cellulose and up-regulated the gene expressions of glutathione S-transferase and antioxidant enzymes. The apoptotic index in the distal colon was the greatest and the expression of Bcl-2 was the lowest in the KGM group 24 h after the AOM treatment. On the other hand, the proliferative index and expression of Cyclin D1 were lower in all fibre groups. Furthermore, KGM increased cecal short-chain fatty acid contents, and both KGM and inulin increased fecal probiotic concentrations. This study suggested that soluble fibres were more effective than cellulose on ameliorating AOM-induced genotoxicity by up-regulating antioxidant enzyme genes, and enhancing epithelium apoptosis by down-regulating Bcl-2.