If a food could make a woman gain breast tissue, the supermarket shelves would be bare of it in short order. In our culture, where nothing symbolizes femininity so much as the female breast, any easy route to a bigger bosom will always be a sure seller. It's true that some foods do contain hormone like substances that can affect the breasts, but if growing bigger breasts were this easy, many cosmetic surgeons would be unemployed.
A woman's breast tissue grows most dramatically in puberty when estrogen levels spike. Also, during adolescence, other pituitary hormones make the estrogen receptors in the breast tissue especially sensitive to estrogen, resulting in a gain in breast tissue that cannot be duplicated later in life. Other factors affect breast size, namely fat disposition on the body. Women who have more fat in the breast area will have larger breasts. However, fat in the breast area is separate from functional breast tissues, and does not respond to hormones any differently than fat elsewhere on the body.
If estrogen levels increase later in life, either naturally---as in pregnancy, or at certain times in a woman's ovulation cycle---or through estrogen supplementation, breast tissues will swell, but the increase in size subsides when estrogen levels decrease again. In pregnancy, overall body fat gain accounts for much of the breast size increase women experience.
Though the gonadal hormone estrogen is found only in animals, certain plants contain other very similar chemicals. These are called phytoestrogens. Phytoestrogens are further divided into isoflavonoids, flavonoids and lignins. In the human body, the phytoestrogens behave very much the same way as human estrogen. Therefore, eating a lot of phytoestrogens can stimulate breast tissues.
Some foods that are high in phytoestrogens are soy foods, flax seeds and sesame seeds. Garlic, dried apricots, sweet potatoes, pomegranates, hummus, olive oil and peanuts contain some phytoestrogens, but much less than flax seeds or soy. Herbal supplements that contain phytoestrogens are saw palmetto, dong quai, red clover and wild yam.
Besides being sold as supposed breast growth supplements, phytoestrogens are touted for their potential ability to decrease symptoms of estrogen deficiency and menopause. Some proponents of phytoestrogens even believe phytoestrogens may help prevent bone loss after menopause. However, phytoestrogens can stimulate estrogen sensitive breast cancer cells. So women who have breast cancer, or who are at risk for breast cancer, should not eat a lot of phytoestrogen-rich foods.
Eating very large amounts of phytoestrogen foods might result in a slight breast tissue swelling. But neither estrogen, nor phytoestrogens will cause a dramatic gain in breast tissue. Also, consuming phytoestrogens in puberty will not change the ultimate size of a woman's breasts, since breast size is largely genetically determined.