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Importance of Location of Digestion and Colonic Fermentation of Starch Related to Its Quality

¹Whistler Center for Carbohydrate Research and Department of Food Science, Purdue University, 745 Agriculture Mall Dr., West Lafayette, IN 47907-2009, U.S.A. ²Instituto Politecnico Nacional, CEPROBI, Km. 6.5 Carr. Yautepec-Jojutla Col. San Isidro, Calle Ceprobi No. 8, Yautepec, Morelos, Mexico. ³Corresponding author. Phone: (765) 494-5668. E-mail: hamakerb@purdue.edu

For decades, quality of starch-based foods has been associated with the in vivo measured glycemic index or the in vitro digestion rate-based categories of rapidly digestible, slowly digestible, and resistant starch (RS). Glycemic index has been related to health-based endpoints mostly through correlative or observational studies, with mechanisms proposed but not well established. Here, we bring forth the concept of locational delivery of glucose from dietary starches to the distal small intestine to elicit an ileal brake effect, as well as short-chain fatty acid production from RS fermentation to cause a colonic brake. Both effects slow gastric emptying and, in turn, extend nutrient (i.e., energy) delivery to the body and may decrease appetite and promote weight management. Slowly digestible starches are currently a popular topic of research, although where they are digested and the released glucose is delivered in the small intestine is not known. A proposal is to further study and establish this mechanism of appetite and food intake regulation so that starch-based ingredients and foods can be developed that promote both the ileal and colonic brake mechanisms.