Soy, also called soybean, is the nutritious seeds of a leguminous plant originally from eastern Asia. For centuries, soy has been a source of high-quality protein and edible oil in many Asian countries. Soy was introduced into the United States in the 18th century via Chinese immigrants. Today, the U.S. is the world's leading soy producer. Although soy can be part of a healthy diet, there have been persistent concerns about the adverse effects of soy estrogens, a group of chemicals, on the human body. So before you decide to take soy supplements, consult your doctor.
Soy Composition
Soy is high in protein. The quality of soy protein approaches the quality of animal protein. Unlike other legumes, soy contains a valuable amino acid called lycine, which is the main building block of protein. Soy is a rich source of mucilage fiber that provides preventive therapy for diabetes and cancer. Soy also provides a good amount of linoleic and linolenic acids, two essential fatty acids, vitamins -- such as ascorbic acid, folic acid and vitamin B6 -- and minerals such as magnesium, potassium and iron, according to the University of Maryland Medical Center.
Soy Estrogens and Breast Cancer
The effects of soy estrogens are similar enough to the body's natural estrogens when estrogen levels are high. Estrogen, the main steroid hormone in the female reproductive system, plays an active role during pregnancy and childbirth. Generally, elevated estrogen levels in the body put women at a higher risk for breast cancer, according to the Sprecher Institute at the Cornell University. Estrogen encourages the proliferation of milk ducts in the breast, which carry the milk through the breast. Most breast cancers occur within these milk ducts.
Soy Allergic Reactions
Soy and soy estrogens have many protective effects on your body; however, there are also some negative effects of taking soy estrogens, such as allergic reactions. People who have allergies to soy can suffer from skin reactions, gastrointestinal disorders, pancreatic problems, dyspnea or difficult respiration and dysphagia or difficulty in swallowing, says the University of Hawaii.
Thyroid Disease
People with impaired thyroid function must consume soy with care, under the supervision of a medical service provider. Soy estrogens may be linked to hypothyroidism, a condition in which your thyroid gland can't produce enough thyroid hormones, the University of Mississippi says. According to the book "The Anti-Estrogenic Diet: How Estrogenic Foods and Chemicals are Making You," soy estrogens have been found to inhibit thyroid peroxidase, an enzyme necessary for the production of thyroid hormones thyroxine and triidothyronine, thereby creating a hypothyroid state. Hypothyroidism can lead to goiter, an enlargement of the thyroid gland, if left untreated.
References
- University of California: eScholarship: Soy and the Thyroid: Can This Miracle Food Be Unsafe?
- The University of Mississippi: Food Intolerance and Allergies
- Cornell University: Sprecher Institute: Phytoestrogens and Breast Cancer
- University of Hawaii: College of Tropical Agriculture and Human Resources: Food Allergies
- "The Anti-Estrogenic Diet: How Estrogenic Foods and Chemicals Are Making You"; Ori Hofmekler and Rick Osborn; 2007
- University of Maryland Medical Center: Soy
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