Intestinal immunomodulatory activity of indigestible glucan in mice and its utilization by intestinal bacteria in vitro

The functional properties of indigestible glucan (IG), a newly developed water-soluble glucose polymer, on intestinal health were investigated. Of high amylose cornstarch, fructooligosaccharides, and IG, IG showed the strongest intestinal IgA induction during the 5-week experiment with BALB/cA mice (3% per diet). Next, separated IG samples, degree of polymerization (DP) ≥ 5 (High-IG) and DP ≤ 5 (Low-IG) fractions, were fed to BALB/cA mice for 9 weeks (3% per diet). High-IG consumption immediately increased the fecal IgA, whereas Low-IG consumption gradually increased it. Fecal mucin was significantly increased in the High-IG group but not in the Low-IG group. To identify utilization of High-IG and Low-IG by intestinal bacteria, in vitro assays were performed using 57 human gut bacterial strains. Few bacteria utilized High-IG, whereas more bacteria, particularly Bifidobacterium strains, utilized Low-IG. These results indicate that IG ingestion benefits the intestinal environment via strengthening the intestinal barrier function and prebiotic effects.