Effects of fructo-oligosaccharide on DSS-induced colitis differ in mice fed nonpurified and purified diets.

We investigated whether feeding a purified compared with nonpurified diet supplemented with or without fructo-oligosaccharide (FOS; 50 g/kg diet) altered the response of C57BL/6 mice to DSS-induced diarrhea. In Expt. 1, we examined disease severity in mice receiving DSS (2% in drinking water) for 5 d. In Expt. 2, we measured cecal organic acid concentrations and fecal water-holding capacity (WHC). In Expts. 3 and 4, we tested whether polycarbophil calcium (PC), a water-absorbing polymer, altered fecal WHC and disease severity. FOS exacerbated diarrhea and weight loss in mice fed the purified diet and reduced fecal bleeding in mice fed the nonpurified diet (P < 0.05). Without DSS administration, cecal acetate and butyrate concentrations were higher in mice fed the nonpurified diet than in mice fed the purified diet (P < 0.05). Fecal WHC was higher in mice fed the nonpurified diet than in mice fed the purified diet (P < 0.05). One day after starting DSS administration, cecal succinate concentrations were higher in mice fed the FOS-supplemented purified diet than in mice fed the other 3 diets, whereas SCFA concentrations were higher in mice fed the nonpurified diet than in mice fed the purified diet (P < 0.05). PC supplementation increased fecal WHC and prevented FOS exacerbation of diarrhea in mice fed the purified diet (P < 0.05). We conclude that the effects of FOS on DSS-induced diarrhea differ in mice fed the purified and nonpurified diets. The protective effect of nonpurified diet was associated with increased production of organic acids and WHC in the intestinal contents.