Effect of Dietary Protein Quality on Development of Aflatoxin B1 -Induced Hepatic Preneoplastic Lesions

Abstract

The effect of the quality of dietary protein on the post-initiation development of aflatoxin B1-initiated putatively preneoplastic foci in Fischer 344 rat liver was compared with the effect of the quantity of dietary protein. Feeding wheat gluten, a low-quality protein, during the postinitiation period (between the end of aflatoxin B1 dosing and the death of the rats) inhibited the development of gamma-glutamyltransferase-positive foci when compared with that in animals fed high-quality protein (casein) diets during the same period. Lysine supplementation of wheat gluten during the postinitiation period enhanced the gamma-glutamyltransferase-positive response to a level comparable with that of the high-quality protein. These results suggest that one can inhibit the development of foci either by decreasing the quantity of protein intake and holding the quality of the protein constant or by decreasing the quality and holding the quantity constant.

Dissimilarity in aflatoxin dose-response relationships between DNA adduct formation and development of preneoplastic foci in rat liver

“…Previous studies have shown considerable variability in AFB-induced foci response among identically treated rats [8,14,26,27]. The source of this variability is unknown but may be compensated for by a large number of animals per group.…”

Risk Assessment for Aflatoxin: I. Metabolism of Aflatoxin B1 by Different Species

“…(14') Finally, decreasing the quality as well as the quantity of dietary protein after aflatoxin exposure inhibits the development of preneoplastic lesions. (148) Choline deficiency in the diet increases the incidence of AFB,-induced tumors in DNA adduct levels followed different kinetics in animals maintained on this diet for 3 weeks prior to exposure and during multiple exposures to AFB, (five daily exposures per week for 2 weeks) compared with animals maintained on the control diet. (150) In particular, AFB,-DNA binding in animals fed the choline-deficient diet was maximal in the middle of each exposure week, compared with no significant peak in adduct levels in control animals.…”

Diet, Energy, and Global Warming

“…Follow-up studies (e.g., Appleton and Campbell 1982;Dunaif and Campbell 1987) addressed cancer promotion after initiation, showing dramatically increased precancerous deformities in response to a given carcinogen dose under high animal protein diets. To unambiguously implicate animal protein in the observed enhanced cancer promotion, Schulsinger et al (1989) compared induced carcinogenesis under high protein diets of animal and plant origins. Cancer promotion was significantly enhanced under animal-protein-rich diet.…”