Lipotrope-modified diets enhance nitrosomethylurea-induced mammary carcinogenesis in female rats.

This study was conducted to determine the effects of lipotrope-modified (deficient or supplemented) diets on nitrosomethylurea- (NMU) induced mammary tumorigenesis. Eighty female Sprague-Dawley rats (4 wks old) were assigned to one of the following groups: control-synthetic diet (CSD), containing all required lipotropes; choline-methionine-deficient diet (CMD); methyl-deficient diet (MDD), lacking all lipotropes; and methyl-supplemented diet (MSD), containing twice as much of each lipotrope as the CSD diet. All animals were injected with NMU after a three-week dietary treatment period. MDD and MSD groups had shorter tumor latency periods (73 and 74 days, respectively) than the CSD group (105 days). Number of tumors per rat was significantly increased in the MDD group (4.6) compared with CSD (1.6), CMD (2.1), and MSD (2.5) groups. The results indicate that dietary manipulation of lipotropes in young female rats enhanced NMU-induced mammary tumorigenesis.