The reason? Increased body fat may promote breast cancer by increasing levels of certain hormones, which in turn raises circulating estrogen levels. High estrogen levels promote breast cancer, since many breast cancers are "estrogen-dependent".
Though there is no conclusive evidence thus far, one fact holds fast. Countries with high-fat diets such as the United States have much higher levels of breast cancer than their lowfat counterparts.
Types of Fat
Research has shown that polyunsaturated fats (corn and safflower oils are two examples) and trans-fatty acids (found in margarines and partially hydrogenated foods) have a positive association with increased breast cancer risk.
Studies have also shown that monounsaturated fatty acids (examples are olive oil and canola oil) do not increase -- and may reduce cancer risk. Finally, consuming omega-3-fatty acids (found in fish oils, fish, and flaxseed) may possibly have a protective effect.
Diets that are higher in plant products are usually lower in fat and result in leaner women who have less potential for the synthesizing of estrogen in fat tissue, and therefore may be at lower risk of breast cancer. Emphasizing a vegetarian-type diet may play a key role in reducing the risk of breast cancer. Additionally, vegetarian-style meals help increase several dietary constituents and micronutrients (vitamins and nutrients) that may play a protective role in the incidence of breast cancer, as discussed below.
