MODULATION OF DIETARY FAT-ENHANCED COLORECTAL CARCINOGENESIS IN N-METHYL-N'-NITRO-N-NITROSOGUANIDINE-TREATED RATS BY A VEGETABLES-FRUIT MIXTURE

The modulation of a vegetables-fruit mixture on N-methyl-N'-nitro-N-ni trosoguanidine (MNNG)-induced colorectal carcinogenesis was studied in rats maintained on a low-or a high-fat diet. For this purpose, 120 ra ts received a semisynthetic diet without (Groups A and C) or with a ve getables-fruit mixture (19.5% wt/wt, Groups B and D) for 35 weeks. Die ts of Group A and B contained 20 (low) energy percent (20e%) fat, wher eas diets of Groups C and D contained 40e% (high) fat. Between Weeks 4 and 9 the animals were given weekly intrarectal instillations of 6 mg MNNG/kg body wt. The colorectal adenocarcinoma incidences showed a si gnificant decrease in animals fed high-fat diets with a vegetables-fru it mixture compared with animals fed a high-fat diet alone. Furthermor e, without a vegetables-fruit mixture, diets high in fat caused a sign ificant increase in adenocarcinoma incidence compared with diets low i n fat. Although nor significant, the adenoma incidences tended to be l ower in animals fed a vegetables-fruit mixture than in animals maintai ned on a diet without this mixture. The results demonstrate that a veg etables-fruit mixture has a significant inhibitory potency on the deve lopment of colorectal tumors induced by MNNG in rats fed diets high in fat.