REDUCTION OF N-NITROSODIETHYLAMINE CARCINOGENESIS IN RATS BY LIPOTROPE OR AMINO-ACID SUPPLEMENTATION OF A MARGINALLY DEFICIENT DIET

  • 1 January 1977
    • journal article
    • research article
    • Vol. 37  (1) , 194-199
Abstract
Induction of hepatocarcinoma by several chemical carcinogens was enhanced in rats fed diets deficient in lipotropes (choline, methionine, folic acid), amino acids and niacin, and high in fat. In some cases, specific supplementation with lipotropes blocked carcinogenesis. In studies reported here, specific supplementation of a marginally deficient diet that enhanced carcinogenesis in rats, with the amino acids or lipotropes in which it was deficient, significantly decreased induction of hepatocarcinoma by N-nitrosodiethylamine. Niacin supplementation decreased hepatocarcinoma incidence only slightly. The addition of beef fat to an adequate diet did not enhance tumor induciton. Rats fed the amino acid- or lipotrope supplemented diets had an increased incidence of hepatic hemangioendothelial sarcomas, compared to deficient rats or rats fed the adequate control diet. Methionine was contained in the amino acid and lipotrope supplements and probably was responsible for reducing hepatocarcinoma incidence. Methionine had an anticarcinogenic effect in other studies and also blocked the depletion of hepatic folate stores that is induced by N-nitrosodiethylamine. Interactions between carcinogens, S-adenosylmethionine and folate may be significant in hepatic or other tissue carcinogenesis. One or more hepatic microsomal oxidases were depressed in rats fed any of the high fat diets but were not correlated with tumor incidence.