Effects of dietary fat type and iron level on in vivo lipid peroxidation in rat colon

Abstract

The effects of dietary fat type and iron level on colonic lipid peroxidation were studied in male Sprague-Dawley rats. Sixty rats were fed a basal diet for 1 week, weighed, and randomly assigned to 1 of 6 diet groups. Each group was fed for 6 weeks 1 of 6 AIN-based diets formulated to contain either 15% ( w w ) corn oil (C), 1% corn oil + 14% beef tallow (B), or 1% corn oil + 14% menhaden oil (M), and 35 or 880 mg iron/kg diet as ferrous fumarate. Feces were sampled at both the start and end of the trial and thiobarbituric reactive substances (TBARS) were measured. Rats were weighed, then sacrificed, at the end of the trial. Samples of mucosa were taken for TBARS measurement and for immunohistochemical staining to detect proliferating cell nuclear antigen (PCNA). Dietary fat type affected (P<0.05) TBARS in both the feces and mucosa (B<C<M) in the same order expected for unsaturation of the fat types. Greater dietary iron increased fecal and mucosal TBARS only in rats fed diets containing menhadden oil. Body weights did not differ throughout the experiment among rats fed the different diets, nor were any changes observed in mucosal sections stained for PCNA. Previous evidence which lipid peroxidation causes cellular damage resulting in increased cellular proliferation, and possibly cancer, and results of this research suggest that supplementation of iron in high unsaturated fat diet is unfavorable for health because of extensive lipid peroxidation.