INFLUENCE OF DIFFERENT DIETS ON DEVELOPMENT OF DMH-INDUCED ABERRANT CRYPT FOCI AND COLON-TUMOR INCIDENCE IN WISTAR RATS

The present study was undertaken to investigate certain dietary factor s known to affect the development of colon cancer for their ability to modulate aberrant crypt foci (ACI;). Male Wistar rats were initiated with oral noses of dimethylhydrazine dihydrochloride (DMH-2HCl, 20 mg/ kg body wt) once a week for to or 20 weeks. Throughout the study the a nimals were fed I) semisynthetic casein-based control diet, 2) control diet with 20% lard, 3) control diet with 20% lard and 20% dietary fib er, or 4) control diet where most of the carbohydrate pool was substit uted with sucrose and dextrin. The composition of the different diets was designed to achieve equivalent intakes of essential nutrients. Ani mals were killed after 10, 20, and 31 weeks. The study showed a pronou nced effect of dietary composition on the development of DMH-induced A CF. The diet high in sucrose and dextrin caused a statistically signif icant increase (p less than or equal to 0.05) in the total number of A CF and number of small and medium ACF. Adding lard to the standard die t did not cause an increase in ACF, bur if the dietary fiber was added to the high-fat diet, a statistically significant reduction (p less t han or equal to 0.05) in the total number of ACF and number of small a nd medium ACF was observed. The values of large and extra-large foci r eflected the same effect of diets on ACF. The results indicate that tu mors in the group fed the diet high in refined carbohydrates were more prominent and occurred with a higher incidence. However, the differen ce is based on few tumors and is not statistically significant. Our re sults do not show that the number of ACF and crypt multiplicity are co nclusively predictive for tumor outcome with the present protocol, whi ch did not include parameters to differentiate between ACF at the cell ular level.