Dietary omega-3 polyunsaturated fats and breast cancer

Although early experimental investigations concluded that quantitative increases in dietary fat promote mammary tumor growth, recent studies have indicated that not all fatty acid families equally express this tumor-promoting capability. This article provides an overview of some of the experimental evidence demonstrating that the omega-6 polyunsaturated fats have significantly different mammary tumor-promoting capabilities from those of the omega-3 polyunsaturated fats. Collectively, these data indicate that whereas increasing dietary levels of omega-6 polyunsaturated fatty acids enhances tumor development, equivalent increases in dietary levels of omega-3 polyunsaturated fatty acids delay or reduce tumor development. Some of the theoretical mechanisms proposed for these contrasting results and their supporting experimental data are discussed.