Comparative effects of soluble fiber (konjac glucomannan and oligofructose‐rich inulin) and insoluble fiber cellulose on the colonic apoptotic response to acute azoxymethane challenge

This study was to compare effects of konjac glucomannan (KGM), inulin and cellulose over the 24‐h apoptotic responses of colonic epithelium cells to an acute azoxymethane (AOM) and cecal short‐chain fatty acids, in mice. Six‐week‐old male C57BL/6J mice (n=72) were randomly assigned to an AIN‐76 modified high‐fat (20%, w/w) low‐fiber (1% cellulose, w/w) control diet or that supplemented with 5% (w/w) of KGM, inulin or cellulose for 3 weeks. Mice were administered with AOM (10 mg/kg B.W., i.p.) on the 22 th day and sacrificed at 0, 6 and 24 h afterwards. Results indicated that the AOM significantly elevated the apoptotic index (AI, apoptotic cells to total cells in a crypt) in the proximal colon of inulin and cellulose groups at 6 and 24 h, of KGM group at 24 h, as compared to those of themselves at 0 h. In the distal colon, AOM promoted the AI of control and cellulose groups to 2–3 folds during the 24‐h period, as compared to that of themselves at 0 h. In contrast, AOM promoted AI of the KGM group to 6 and 5 folds, of the inulin group to 4 and 2.5 folds at 6 and 24 h, as compared to that of themselves at 0 h. Further, KGM was the only fiber that promoted the cecal butyrate concentration. Therefore, KGM showed the most effective fiber in this study to defend against the acute challenge by AOM. This study was supported by the National Science Council Grant NSC‐99‐2320‐B‐040‐014‐MY2, Taiwan.