Soy & Estrogen Dangers

Soy is the edible seed of a subtropical plant native to southeastern Asia. It is a low-cost source of protein for hundreds of millions of people around the world. Nutrition experts consider soy equivalent to milk and meat in terms of the quality of protein it contains. Soy foods are rich in isoflavones, a group of plant estrogens, especially genestein and daidzein, which have been studied scientifically for their potential effects on many health disorders. However, soy isoflavones have undesirable properties as well; therefore, you should consume soy foods with care after talking to your doctor.

Plant Description

Soy is a product from a hairy Asian legume called Glycine max. It is a midsize, hardy plant, with numerous branches. The flowers are white or purple. Glycine max has been cultivated in Asian countries for at least 5,000 years for food and oil. Early Chinese immigrants brought soy to the United States. Today, the U.S. is the world's leading soybean producer.

Soy Composition

Soy yields a very high quality protein and edible oils. It contains about 40 percent protein and 20 percent oil, along with a good amount of minerals, salts, and vitamins such as ascorbic acid, thiamine and riboflavin. Soy also provides relatively high amounts of linoleic and linolenic acids, two categories of essential fatty acids thought to have cardiovascular effects through lowering cholesterol.

Adverse Effects of Soy and Estrogens

Soy is moderately safe; however, a few people are allergic to soy and must avoid it. Generally, fermented soy foods, such as tofu, miso, natto and shoyu, cause allergies less often than raw soybeans. People allergic to soy can suffer from skin reactions, stomach disorders, difficulty in swallowing or difficult respiration. Soy isoflavones have been found to inhibit the production of thyroid hormone, resulting in hypothyroidism in some individuals, according to the University of Mississippi. Hypothyroidism, if left untreated, can lead to malaise, constipation, sleepiness and even goiter, an enlargement at the front of the neck.

Amounts

In general, 20 g to 35 g of soy protein, including 80 mg of isoflavones, per day is fine for healthy individuals, according to "Prescription for Drug Alternatives: All-Natural Options for Better Health," a book by James Balch and his colleagues. However, people who cannot tolerate the proteins found in soy should not eat soy products containing added isoflavones more than once or twice a week.