Changes in preneoplastic response to aflatoxin B1 in rats fed green beans, beets or squash.

Weanling male Fischer rats were fed diets containing 25% freeze-dried green beans, beets or squash either with or without 1 ppm aflatoxin B1 for 8 wk. Plasma alpha-foetoprotein concentrations were determined weekly from wk 4 to 7. During wk 8 the animals were killed and hepatic sections were stained for gamma-glutamyl transpeptidase. All three vegetable diets, as compared to the basal semi-purified diet, enhanced both aflatoxin-B1-induced elevation of plasma alpha-foetoprotein and aflatoxin-B1-induced emergence of hepatic cell foci of gamma-glutamyl transpeptidase. The data suggest that these vegetables contain natural factors that enhance aflatoxin B1 carcinogenicity.