Mammary carcinogenesis in rats fed different amounts and types of fat.

Rats fed 20% corn oil or lard showed increased 7,12-di methylbenzanthracene-induced mammary tumorigenesis and slightly increased growth rate compared to rats fed 5% fat; 20% corn oil accelerated sexual maturation, but 20% lard did not. In contrast,diets high in beef fat (30%) depressedtumor Induction by 7,12-dimethylbenzanthracene or N-fluorenyla cetamide compared to a diet containing 15% vegetableoil; dietary lipotrope content had no effect on tumorigenesis. Fur ther studiesare neededof the effects of type and amountof dietary fat on mammary tumorigenesis in several model sys tems.