The protective effect of a dietary high-amylose cornstarch (HAS) against trinitrobenzene sulfonic acid (TNBS)-induced colitis was examined in rats. Rats were fed a HAS-free basal diet or, a 15% or 30% HAS supplemented diet for 10 d, and then received intracolonic TNBS to induce colitis and fed the respective diets for a further 8 d. HAS ingestion significantly protected colonic injuries as evidenced by lower colonic myeloperoxidase activity. Rats fed the HAS diet showed greater cecal short-chain fatty acid (SCFA) production than those fed the basal diet. Further, just before TNBS administration, HAS ingestion dose-dependently increased fecal and cecal mucin contents, and protein and nucleic acid contents in the colonic mucosa. HAS ingestion also reduced colonic permeability. The protective effect of HAS ingestion on TNBS-induced colitis is perhaps exerted through alterations in colonic mucosa, possibly due to cecal SCFA production.Key words: high-amylose cornstarch; trinitrobenzene sulfonic acid; short-chain fatty acids; mucin; ratsThe etiology of inflammatory bowel disease, encompassing Crohn's disease and ulcerative colitis, remains unknown, but studies in animal models suggest that disruption of mucosal barrier function may induce abnormal immune responses to luminal bacteria, resulting in acute and chronic inflammation in the large bowel.1) Mucosal barrier function has been ascribed to colonic epithelial cells based on mucus production and shedding of surface cells, which are replenished by renewal from crypt cells.2) In this regard, short-chain fatty acids (SCFA: mainly acetate, propionate, and butyrate), products of large bowel fermentation by bacteria, have been reported to be major fuels for colonic epithelial cells and to accelerate epithelial cell proliferation. 3,4) Earlier studies indicated that SCFA irrigation stimulated the mucosal repair process and decreased inflammation in human patients 5) and rats injected with trinitrobenzene sulfonic acid 6) (TNBS). Also, Barcelo et al. 7) found that a physiological concentration of butyrate and acetate caused a significant increase in mucus secretion in the lumen of isolated perfused rat colon. Greater mucin production might contribute to the lower incidence of bacterial translocation across the gut barrier reported in studies that fed dietary fiber. 8) Clearly, SCFAs are considered to be of benefit in the treatment of inflammatory bowel disease.Although SCFA delivery to the colon might be accomplished with an enteric-coated capsule or a rectal infusion of SCFA, the nutritional approach is more physiological, consistent, and cost-effective, and less stressful. One potential route is to increase the consumption of foods high in resistant starch, because studies in experimental animals have shown that the feeding of resistant starch, such as high-amylose cornstarch (HAS), increases the large bowel digesta SCFA level in rats [9][10][11] and pigs. 12) Previously we found that ingestion of HAS prevented endotoxin influx from the intestinal tract into the portal ...