The effect of dietary quercetin and rutin on AOM‐induced acute colonic epithelial abnormalities in mice fed a high‐fat diet

Abstract

Dietary quercetin (QU) and rutin (RU), phenolic flavonoids found in many fruits and vegetables, when fed to mice on a low‐fat diet successfully modified the response to azoxymethanol (AOM) by initially inhibiting hyperproliferation and the formation of foci of dysplasia (FADs) and ultimately reducing tumor incidence (Carcinogenesis 12, 1193–1196, 1991). In this study, we tested the efficacy of QU and RU when a high‐fat diet was presented. An AIN 76A diet made with 20% corn oil (CO) was supplemented with QU (0.5%, 2.0%, or 5.0%) and RU (2.0% or 4.0%). These five diets, as well as a 5.0% and a 20.0% CO diet, were fed to a group of CF1 female mice for nine weeks. Both QU and RU showed nonsignificant dose‐related trends toward normalization of the AOM‐induced upward extension of S phase cells. Examination of 500 μm of serially sectioned distal colon revealed that 29% of mice fed the 20% CO control diet were free of FADs. Among the mice fed QU, regardless of dose, >80% were free of FADs. When the three groups fed QU were pooled and compared with the control 20% CO‐fed mice, the degree of protection was significant (p < 0.01). Mice fed RU expressed a level of protection that bordered on the significant (p < 0.08). These data suggest that, regardless of the fat content of the diet, QU and RU are capable of modifying or inhibiting events in the development of chemically induced colonic neoplasia.