The prebiotic characteristics of fructooligosaccharides are necessary for reduction of TNBS-induced colitis in rats.

Fructooligosaccharides (FOS) increase the growth of lactic acid bacteria (LAB) and promote butyrate and lactate production. Because of these properties, FOS may benefit intestinal inflammation. The purpose of this study was to investigate the effect of FOS on colitis in rats and determine which factors are involved. Groups of rats with intracolonic trinitrobenzene sulfonic acid (TNBS)-induced colitis received intragastric infusions of 9 g/L NaCl, 1 g/d FOS or 10(11) colony-forming units (cfu)/d LAB (Experiment 1), or intracolonic infusions of 9 g/L NaCl, butyrate, lactate or butyrate + lactate with or without 10(9.5) cfu/d LAB (Experiment 2). Each infusion was administered twice daily for 14 d. Intragastric FOS reduced the gross score for inflammation (P < 0.001), myeloperoxidase (MPO) activity (P < 0.001) and pH (P < 0.001), and increased lactate (P = 0.02) and butyrate concentrations (P < 0.001) as well as LAB counts in the cecum (P < 0.01). Intragastric LAB (10(11) cfu/d) had the same beneficial effects as FOS and modified the cecal composition similarly. High doses of intracolonic butyrate and lactate reduced the indices of inflammation (P < 0.001), whereas administration of the lower concentrations found in the colon tended to decrease (P < 0.1) the gross score for inflammation and MPO activity. Addition of LAB (10(9.5) cfu/d) to the organic acids was necessary to reproduce the significant FOS-induced effects on these variables. Thus, under the experimental conditions used, FOS reduced intestinal inflammatory activity mainly by increasing LAB counts in the intestine.