A proposed mechanism for effects of diet on mammary cancer.

Growth and development of mammary glandular parenchyma appear to be strongly influenced by the associated adipose tissue. Because fat is the major form of energy storage in the body, any changes in energy balance will be reflected in the weight of adipose tissue to a greater extent than in body weight as a whole. High-fat diets tend to encourage energy storage and may promote mammary cancer by increasing the amount of adipose tissue in the gland. The intimate association of adipose and glandular tissue would facilitate the transfer of any growth-promoting substances, such as polyunsaturated fatty acids, eicosanoids, estrogens, or other growth factors, from the adipose to the glandular tissue. Conversely, low-fat diets or restriction of food intake may decrease the risk of mammary cancer by reducing the amount of adipose tissue and thus reducing exposure of the glandular tissue to such growth-promoting substances.