Effects of diet on chemically induced bowel cancer.

One hundred and twenty-seven rats were fed one of four diets containing graded amounts of fibre or a diet with vitamin A supplements and were given, subcutaneously, dimethyl-hydrazine or saline. Stool weight correlated directly with fibre intake and the frequency of colonic tumours decreased as fibre intake increased. An artificial fibre-free diet was also associated with a reduction in the number of colonic tumours. Major changes were noted in the profile of bacteria from one dietary group to another but no correlation with the frequency of tumours was noted. A diet which provided vitamin A supplements sufficient to retard growth and raise serum and liver concentrations of the vitamin resulted in a modest reduction in the number of tumours.