EFFECTS OF DIETARY-FAT TYPE AND IRON LEVEL ON IN-VIVO LIPID-PEROXIDATION IN RAT COLON

The effects of dietary fat type and iron level on colonic lipid peroxi dation 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 formulat ed to contain either 15% (w/w) corn oil (C), 1% corn oil + 14% beef ta llow (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 (TEARS) were measured. Rats were weighed, then sacrificed, at the end of the trial. Samples of mucosa were taken for TEARS measurement and for immunohist ochemical staining to detect proliferating cell nuclear antigen (PCNA) . Dietary fat type affected (P < 0.05) TEARS in both the feces and muc osa (B < C < M) in the same order expected for unsaturation of the fat types. Greater dietary iron increased fecal and mucosal TEARS 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 e vidence which lipid peroxidation causes cellular damage resulting in i ncreased cellular proliferation, and possibly cancer, and results of t his research suggest that supplementation of iron in high unsaturated fat diet is unfavorable for health because of extensive lipid peroxida tion. (C) 1997 Elsevier Science Inc.