Dietary Fermentable Fiber Reduces Intestinal Barrier Defects and Inflammation in Colitic Mice

Dietary fiber (DF) and its fermentation metabolites play an important role in establishing and maintaining intestinal health.

This study investigated the effects of fermentable DF, guar gum (GG), and partially hydrolyzed GG (PHGG) on the epithelial tight junction (TJ) barrier and inflammation in a murine model of dextran sodium sulfate (DSS)-induced colitis.

In Expt. 1, male, 7-wk-old BALB/c mice weighing ∼21 g were fed diets with 0%, 5%, and 10% GG for 12 d and administered distilled water with 2% DSS for 7 d beginning 5 d after the start of feeding. In Expt. 2, mice were provided diets with or without 10% PHGG and GG for 13 d and administered distilled water with 2% DSS for 8 d from 5 d after the start of feeding. In Expt. 3, mice were provided diets with or without 10% PHGG and GG for 14 d without DSS administration. Colitis score, colon TJ proteins, and fecal SCFA concentrations were analyzed.

In Expts. 1 and 2, the clinical score in the DSS group was ∼100% greater than that in the DSS+10% GG and PHGG groups on days 12 and 13 (P < 0.01). The DSS+10% GG and PHGG groups showed ∼110%, 60%, 120%, and 110% greater (P < 0.05) expression of occludin and claudin 3, 4, and 7, respectively, in the colon than did the DSS group. The DSS+10% GG and PHGG groups had greater total fecal SCFA concentrations (25.1 and 12.0 mmol/L) than did the DSS group (3.3 mmol/L) on day 9 (P < 0.01). TJ protein expression did not differ between groups in Expt. 3.

These findings suggest that microbial metabolites of PHGG and GG, and possibly SCFAs, reduce intestinal barrier defects and inflammation in colitic mice.