Disclosed are compositions and corresponding methods for treating fibrocystic breast disease or other breast-related disease or condition. The compositions comprise, per serving or dose, from zero to about 400 μg selenium, from about 100 mg to about 6000 mg gamma linolenic acid, and about 0.15 mg to about 5 mg iodine, with nutritional embodiments further comprising one or more of protein, fat, carbohydrate, vitamins, and minerals and providing from about 50 to about 1000 kcal of energy per severing or dose. Also disclosed are in-vitro studies showing that certain combinations of gamma linolenic acid, iodine, and/or selenium may 1) inhibit breast cancer or fibrocystic cell proliferation, 2) reinforce the function of tight junctions of endothelial cells and of mammary epithelial cells in estrogen-sensitive conditions, and 3) reduce the risk of vascular invasion by breast cancer cells.