Hormones belong to different groups of substances, the most important of which are the peptide hormones and the steroid hormones. The specific effects on the cells of the target organ is exclusively based on the fact that only these cells are equipped with the necessary hormone receptors. Hormone receptors are usually proteins that change their conformation and activity according to their binding state. They elicit a signal within the cell that controls the cell’s metabolism. Thus only the receptor-containing cells are signal receivers.

Many different plants produce compounds that may mimic or interact with estrogen hormones in animals. At least 20 compounds have been identified in at least 300 plants from more than 16 different plant families (1). Referred to as phytoestrogens, these compounds are weaker than natural estrogens and reside in herbs and seasonings (garlic, parsley), grains (soybeans, wheat, rice), vegetables (beans, carrots, potatoes), fruits (date, pomegranates, cherries, apples) and drink (coffee).

When consumed as part of an ordinary diet, phytoestrogens are probably safe and may even be beneficial. In fact, phytoestrogens have been investigated as possible cancer preventatives and as treatments for menopause and osteoporosis (1).

 Laboratory animal experiments and comparisons of Asian and Western human populations suggest that diet has a large role in these types of health problems. One study found that Asian populations that eat large amounts of soy products - which contain high levels of phytoestrogens - have lower rates of hormone-dependent cancers (breast, endometrial) and a lower incidence of menopausal symptoms and osteoporosis than do Westerners, who don't traditionally eat these products. Asian immigrants to Western nations also increase their risks of these illnesses as they Westernize their diets to include more protein and fat and reduce their fiber and soy.

Summary:

1. Barrett, J. 1996. Phytoestrogens: Friends or foes? Environmental Health Perspectives 104:478-82. (http://ehpnet1.niehs.nih.gov/docs/1996/104(5)/focus.html)