Inhibition of intestinal tumorigenesis in methylazoxymethanol-treated rats by dietary restriction.

Male Sprague-Dawley rats were inoculated once with methylazoxymethanol (MAM) and groups were fed restricted diets for the following 140 days: Group A or B was fed a 12-g diet daily (25% restricted) from Day 10 or Day 63 after MAM, respectively. Group C or D was fed ad libitum only every other day from Day 8 or Day 31 after MAM, respectively. Control MAM-treated rats were fed the same diet ad libitum. When examined at Day 140, there was a significant reduction of intestinal tumors in Group A on the restricted diet from Day 10; however, among all other groups there were no significant differences in tumor incidences. Later onset of daily dietary restriction or of feeding and fasting every other day did not change the pattern of tumorigenesis from that which developed in control rats fed ad libitum.