Potential of selected dietary oils in azoxymethane induced colon cancer

B11

Dietary fat, depending on the source, (i.e. Animal or vegetable), quantity and fatty acid composition (saturated, monounsaturated and polyunsaturated), may have implications in colon cancer. The objective of this study was to compared the inhibitory effects of red palm oil (RPO), wheat germ oil (WGO), rice bran oil (RBO), flaxseed oil (FSO), corn oil (CO) and soybean oil (SBO) at 7% (normal fat level ) and 14% (high fat level) on Azoxymethane (AOM) induced aberrant crypt foci (ACF). We also determined the long term effects (end point tumor study (EPT)) of dietary fat from the above sources on colon cancer in F344 male rats.
 >In the ACF study 2 groups of F344 rats (4wks old) (n=6) received AIN-93G control (C) diet containing 7% and 14% soybean oil (SBO), respectively. The remaining groups were assigned treatment diets consisting of 7% and 14% RPO, WGO, RBO, FSO and CO, respectively. The rats remained on their respective diets for 13wks. The rats in the EPT study were fed a control (AIN-93G) diet consisting with 7% SBO, while the treatment groups were fed diets containing 7% RPO, WGO, RBO, FSO and CO, respectively. At 20wk of age rats in the EPT study were switched to AIN-93M diets. All rats received 2 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 ACF in the colon of rats fed SBO, WGO, RPO, RBO, FSO and CO at 7 and 14% levels ranged from 46 to 189. In the EPT study, all the rats fed 7% SBO and CO developed tumors (100% incidence) while tumor incidence in the groups fed WGO, RBO, FSO ranged from 39% to 79%. Tumor size (mm) ranged from 1.77 to 6.50.
 >Our results indicate that the type and constituents (such as n-3 PUFA, carotenoids, vitamin E, phytosterols) in dietary fat plays a significant role in the incidence of AOM induced colon tumors in Fisher 344 rats. Dietary fats rich in phytochemicals may have implications in colon cancer.