ABSTRACT
Dietary fiber has been reported to prevent preneoplastic colon lesions. The aim of this study was to determine the effect of resistant starches, novel dietary fibers, on the development of colonic preneoplasia and Wnt signaling in azoxymethane (AOM)-treated rats and mice fed resistant starches at 55% of the diet after AOM treatment. Another objective was to determine the effect of resistant starches on the development of preneoplasia in rats treated with antibiotics (Ab), administered between AOM treatment and resistant starch feeding. Diets containing resistant starches, high-amylose (HA7), high-amylose-octenyl succinic anhydride (OS-HA7), or high-amylose-stearic acid (SA-HA7) were compared with control cornstarch (CS). The resistant starch content of the diets did not alter the yield of colonic lesions but animals treated with AOM and fed the diet with the highest resistant starch content, SA-HA7 developed the highest average aberrant crypt foci (ACF) per animal. Mice fed the OS-HA7 diet had decreased expression of some upstream Wnt genes in the colonic crypts. This study suggests that further research is needed to determine if resistant starch impacts colon carcinogenesis in rodents.
Acknowledgments
This research was funded by Plant Sciences Institute at Iowa State University and the United States Department of Agriculture (USDA) NRI/AFRI Project “Effects of lipids on physical properties, digestibility and nutritional benefits of starchy foods.” The authors appreciate the contributions of Toni Christofferson for histopathology processing and sectioning, Margie Carter for assistance with LCM, and Dr. Angela Pillatzki for assisting in optimizing research protocols. They would also like to thank Reed Faldet, Catie Mullen, Dana Pralle, and Kylie Thompson for the extensive help with the care of the mice.