Source: Women's Therapeutic Institute

Phytoestrogens, Naturally Occurring Plant Estrogens Plants produce chemicals that mimic estrogen, and block progesterone. In general, it is thought that they tend to wash out of the body within several days in contrast to months or decades that the xenoestrogens take to be excreted. Whole grains, fruits, seeds, beans and herbs all are know to have estrogen and/or progesterone activity. In general, any food that has been eaten by a culture or people group for centuries is probably all right to eat if the people group in question is relatively free from these estrogen related diseases.

When referring to phytoestrogens, it is generally thought that a "weak" estrogen may actually be protective against cancer causing xenoestrogens. The best example, is Lilian Thompson PhD’s work that showed that oral ground flax seed reduced breast cancer size to one half between the time of diagnosis and surgery. A strong phytoestrogen may actually make the disease worse. Again the list that follows is incomplete because of the lack of research money and interest:

Coffee is a known phytoestrogen. Coffee is commonly known to make fibrocystic breast disease worse. It is not thought to be the caffeine, but coffee itself mimics estrogen strongly. Thus, decaffinated coffee still may be estrogenic.

Clover, Red Clover tea, Alfalfa Sprouts. Australian sheep grazing on imported European clover developed still births and sterility 3 years later. Finally, formononetin was determined to be the culprit. Formononetin mimics estrogen.

Sunflower Seeds. Coumestrol found in sunflower seeds when fed to the mother rat caused permanent reproductive problems in the rat pups: female pups when grown did not ovulate, and the male pups had altered mounting behavior and fewer ejaculations. Neonatal rats and immature rats exposed to coumestrol had premature estrous cycles. Flax seed oil and Soy oil are known NOT have the active phytoestrogens. Sunflower oil MAY or MAY NOT have active hormone components in it.

Queen Anne's lace (wild carrot) During the fourth century B.C., Hipocrates noted that Queen Anne's Lace prevented pregnancies. It is now know that that seeds contain a chemical know to block progesterone needed to maintain a pregnancy.

Pomegranate The Greeks used this plant as a contraceptive. Modern research confirms strong estrogen activity.

The article continues here (it's very long but worth the read)

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