Chemopreventive potential of selected cereals on chemically induced colon cancer in a Fisher 344 rat model

B12

Dietary fiber has been shown to have implications in colon cancer. In this study we examined the effects of selected cereals which are significant sources of dietary fiber (wheat bran (WB), rice bran (RB), yellow corn meal (CM) and flaxseed meal (FM) on the incidence of (AOM) induced colon tumorigenesis (Aberrant crypt foci (ACF) and End point tumor(EPT) studies) in Fisher 344 male rats.
 >Fisher 344 male rats were randomly assigned into 20 groups after a 1 wk acclimatization period. For ACF study, Fisher 344 male rats were fed AIN-93G control diet (C) (n=6) and treatment groups (n=6); WB, RB, FM and CM at 5 and 10% levels. In EPT study, 20 groups of rats (n=14) were initially assigned AIN-93G control diet (C) and treatment groups; WB, RB, FM and CM at 5 and 10% levels. At 20wk of age rats were switched to AIN-93M diets. All rats received two S/c injections of AOM at 7 and 8 wk of age @ 16 mg/kg body weight in saline. At 45 wk of age all rats were killed by CO2 asphyxiation.
 >Total number of ACF (SEM±) in the colon ranged from 26 to 160 for groups fed C, WB, RB CM and FM. Tumor incidence (%) in C, WB, RB CM and FM ranged from a low of 31% in rats fed selected cereals to a high of 100% in control group. Tumors/ tumor bearing rats (TBR) and tumor size (mm) were significantly (p<0.05) lower in the rats fed the treatment diets (WB, RB CM and FM) compared to the control. All the rats fed cereal diets had significantly (p<0.05) higher glutathione-S-transferase (GST) activity (µmol/g protein) compared to rats fed control diets.
 >Our results suggests that feeding wheat bran, rice bran, corn meal and flax meal which are significant sources of dietary fiber at 5 and 10% levels significantly (P<0.05) reduced the incidence of AOM induced colon tumors in Fisher 344 male rats. We conclude that the protective effects of WB, RB, CM and FM against colon tumorigenesis may possibly be attributed to the synergistic/additive actions of phytochemicals and fiber contained in these foods.