Can elemental diets reduce the intestinal toxicity of 5-fluorouracil?

In order to test the hypothesis that elemental diets protect the intestinal mucosa against 5-fluorouracil toxicity, we have estimated water absorption, cytoplasmic peptide hydrolase activities, and mucosal DNA contents in isolated intestines from rats fed on one of three elemental diets or a standard diet and injected with 5-fluorouracil. Water absorption rates were significantly increased when rats, not injected with 5-fluorouracil, were fed on Flexical or Vivonex-HN. However, water absorption was severely impaired 3 days after administration of 5-fluorouracil and none of the elemental diets alleviated this impairment of absorption. Cytoplasmic peptide hydrolase activities and mucosal DNA contents were also severely decreased after 5-fluorouracil injection, the changes observed being independent of the diet. Also, none of the elemental diets reduced the body weight losses observed after 5-fluorouracil administration. Although the effects of the sodium salt of 5-fluorouracil on body weight and food intakes were much less severe than those of the Tris salt the two salts had identical effects on intestinal absorption even when an elemental diet was used. Although there was a smaller incidence of diarrhea after 5-fluorouracil administration when the rats had been fed on one of the elemental diets, diet B, the results do not support the suggestion that elemental diets might reduce the intestinal toxicity of 5-fluorouracil.