Natural Standard® Patient Monograph, Copyright © 2014 (www.naturalstandard.com). All Rights Reserved. Commercial distribution prohibited. This monograph is intended for informational purposes only, and should not be interpreted as specific medical advice. You should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.

Background

Soy is a subtropical plant, native to southeastern Asia. This member of the pea family grows from one to five-feet tall and forms clusters of three to five pods, each containing two to four beans per pod. Soy has been a dietary staple in Asian countries for at least 5,000 years, and during the Chou dynasty in China (1134-246 B.C.), fermentation techniques were discovered that allowed soy to be prepared in more easily digestible forms such as tempeh, miso, and tamari soy sauce. Tofu was invented in 2nd-Century China.

Soy was introduced to Europe in the 1700s and to the United States in the 1800s. Large-scale soybean cultivation began in the United States during World War II. Currently, Midwestern U.S. states produce approximately half of the world's supply of soybeans.

Soy contains protein, isoflavones, and fiber, all thought to provide health benefits. Soy is an excellent source of dietary protein, including all essential amino acids. Soy is also a source of lecithin or phospholipid. Soy isoflavones and lecithin have been studied scientifically for numerous health conditions. Isoflavones such as genistein are believed to have estrogen-like effects in the body, and as a result are sometimes called "phytoestrogens."

Common sources of soy isoflavones include roasted soybean, green soybean, soy flour, tempeh, tofu, tofu yogurt, soy hot dogs, miso, soy butter, soy nut butter, soy ice cream, soy milk, soy yogurt, tofu pups®, soy cheese, bean curd, seitan, and soy noodles. Soybean flour is found in Spanish sausage products (chorizo, salchichon, mortadella, and boiled ham), doughnuts, and soup stock cubes. Although processed soy foods (e.g., veggie burgers, tofu pups®, meatless dinner entrees, chicken-free nuggets, soy "ice creams" and energy bars) are usually high in protein, they typically contain lower levels of isoflavones.

Soy protein has also been investigated for benefit in terms of heart disease risk factors, reducing menopausal symptoms, weight loss, arthritis, brain function, and exercise performance. Dietary soy may decrease the risk of breast cancer in women and prostate cancer in men, as well as other types of cancers. In general, the supportive evidence for use of phytoestrogens as treatments for menopause, heart disease, bone disease, weight loss, and cancer is limited. The use of soy formula has been investigated in the treatment of diarrhea in infants and is an effective and safe alternative to cow's milk formula in most infants.

This evidence-based monograph was prepared by The Natural Standard Research Collaboration

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