Soy is an edible crop that serves as a major subsistence staple in East Asia. It is a good source of protein but contains much less saturated fat than animal products. Thus, soy can make a good substitute for meat. Soy also provides many essential micronutrients, such as amino acids and fatty acids. These micronutrients cannot be synthesized by your body but are necessary for survival. However, soy formulas are not recommended for everyone. Ask your doctor before you take soy supplements.
Breast Cancer
Soy protein contains two major isoflavones, daidzen and genistein, which are broadly similar in chemical structure to the main female hormone estrogen. Similarities in the molecular structure of soy isoflavones facilitate binding to estrogen receptors. As a consequence, soy phytoestrogens can mimic some of estrogen's effects. Thus, soy can actually increase estrogen levels in the body. It has long been noted that estrogen causes the breast cancer tumor to grow. Thus, soy's effect on estrogen levels increases the risk of breast cancer in women.
Soy Allergy
Soy allergy occurs when the body's immune system misinterprets a specific soy protein as a pathogen and attacks it. The immune system responds by creating specific antibodies, such as histamine, which work directly on the respiratory system, gastric and cardiovascular systems, causing allergy symptoms like nausea, diarrhea, stomachache and low blood pressure. Raw soybeans are reported to have increased allergenicity than hydrolyzed soy foods like soy milk, soy sprouts, tofu and miso.
Thyroid Disease
Soy can lead to underfunctioning of the thyroid gland, called hypothyroidism. Soy isoflavones are considered antithyroid compounds. They reduce the activity of thyroid peroxidase, which plays a central role in the function of the thyroid gland. When your thyroid gland becomes underactive, you might experience tiredness, lethargy, depression, weight gain, hair loss, poor memory and goiter.
Gout
Gout is a painful condition that results from a buildup of uric acid in joint spaces. Uric acid is a breakdown product of purines that are constituent parts of DNA and RNA. The cylindrical or needle-like crystals of uric acid arrange radically around a joint and cause extreme pain, swelling, inflammation, and redness. People with gout should not eat a lot of soy products because they are high in purines.
Soy and Menopausal Symptoms
Soy has become popular in the United States for reducing menopause symptoms, but more human trials are needed before firm conclusions can be drawn. A drop in estrogen levels can lead to hot flashes, night sweats, mood swings and vaginal dryness. Soy isoflavones prevent a decrease in serum estrogen levels and reduce the symptoms of menopause. Part of the reason is that isoflavones have a functional similarity to the estrogen hormones women produce.
Soy and Osteoporosis
Soy is being evaluated clinically for the treatment and prevention of osteoporosis, a bone disease, in older women. Osteoporosis is more often seen in postmenopausal women with estrogen deficiency. It occurs when the body fails to form enough new bone. As a result, the bones become less dense and break easily. Soy isoflavones, including daidzen and genistein, can attenuate bone loss and thus reduce the risk of fracture, the Baylor College of Medicine notes.
References
- University of Maryland Medical Center; Soy; Dec. 14, 2009
- Cornell University: Sprecher Institute; Phytoestrogens and Breast Cancer;Barbour S. Warren, et al.; Jul. 1, 2002
- University of Mississippi; Food Intolerance and Allergies; 2003
- "Food Allergies: Let Us Know, WeCare"; Alfonso Tirado; 2005
- "The Anti-Estrogenic Diet: How Estrogenic Foods and Chemicals Are MakingYou Fat and Sick"; Ori Hofmekler and Rick Osborn; 2007
- Florida Agency for Health Care Administration; Soy; May 3, 2009
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