Soy

Glycine max

An annual, soy grows up 1 to five feet tall. Soy has an erect, semi-trailing stem and trifoliate leaves that are covered in fine, downy hair. Flowers are white or purple, and the oblong pods contain up to four yellow to brownish seeds.

Soy offers tremendous health benefits when incorporated into your diet. It's an inexpensive, high-quality, vitamin- and mineral-rich plant protein with lots of soluble fiber, plant-based omega-3 fatty acids, and, most important, it offers a wealth of disease-fighting phytonutrients. Indeed, soy is the richest known dietary source of powerful health-promoting phytoestrogens. Soy has been recognized by many researchers as playing a positive role in preventing cardiovascular disease, cancer, and osteoporosis as well as helping to relieve menopausal and menstrual symptoms.

Soybeans have been cultivated in China since the eleventh century B.C. Indeed, the soybean is the most widely grown and utilized legume in the world. The Chinese name for the soybean is "greater bean," and soy is also referred to as "meat without bones." Like other beans, soybeans grow in pods, and while we most commonly think of them as green, they can also be yellow, black, or brown. The soybean was introduced to America in the eighteenth century by that innovative, forward-looking American Ben Franklin, who, impressed with tofu-the Chinese "cheese made from soybeans"-had some beans shipped from Paris to a group of farmers in Pennsylvania.

Soy has long been recognized as a highly nutritious food. Western scientists became particularly interested in soy when they noticed that people eating Asian diets enjoyed lower rates of heart disease as well as less cancer and osteoporosis, and had fewer hormonal problems than those eating a typical Western diet.

Soy's most conclusively demonstrated benefit concerns cardiovascular health. There have been extensive studies on the cholesterol-lowering effect of soy. One of them describes an analysis of thirty-eight different studies. Consumption of soy protein resulted in significant reductions in total cholesterol (9.3 percent), LDL cholesterol (12.9 percent), and triglycerides (10.5 percent) with a small though not significant increase in HDL cholesterol. The intake of soy foods among the premenopausal women subjects was inversely related to their risk for coronary artery disease and stroke as well as other disorders.

Soy has also been shown to be a potent cancer-fighting food. Various components of soy have demonstrated anti-carcinogenic effects. They include protease inhibitors, phytosterols, saponins, phenolic acids, phytic acid, and isoflavones. Two of the isoflavones in soy-genistein and daidzein-are worthy of particular attention because soy foods are their primary dietary source. These two isoflavones act like weak estrogens in the body. While their effects aren't completely understood, we do know that they can compete with stronger naturally occurring estrogens and in this way help prevent hormone-dependent cancers like those of the breast and prostate. The isoflavones bind to sites on cell membranes which would normally be inhabited by hormones that can stimulate the growth of tumors. In addition to blocking the action of potent, naturally produced hormones, genistein can also inhibit the activity of enzymes that encourage the growth of blood clots and tumors. While there have been some variations in study results linking soy intake to breast cancer reduction, epidemiological studies show that women in Southeast Asian population who consume diets high in soy protein have a four to six times reduced risk of breast cancer compared with American women who normally consume minimal amounts of soy.

There were reports, eventually disproved, that soy led to an increase in the development of senility. Indeed, most populations at the higher end of soy consumption have lower rates of dementia than populations who do not consume soy.

Some evidence says soy helps with menopausal symptoms. For example, researchers from the University of Bologna, in Italy, gave two groups of menopausal women 60 grams of either soy protein or a look-alike placebo of dried milk protein daily for twelve weeks. The women eating soy protein experienced significantly fewer hot flashes and night sweats than the placebo group. Again, soy's estrogen mimicking isoflavones are responsible. As a woman's natural levels of estrogen fall during menopause, the isoflavones seem to help take up the slack. There is evidence that, because of its estrogen like behavior, soy contributes to bone health and thus helps stave off osteoporosis.

Other names

• Soya
• Soybean

Parts used

Seed, bean.

Uses

Known as the "cow of China", soy has been cultivated in China since at least the 11th century B.C. In Japan during the annual Setsubun - beginning of Spring - festival, celebrants scatter lucky roasted soybeans at home to ward off evil and to welcome in the new year with happiness. These soybeans are then eaten in a quantity equivalent to ones age to guarantee good health for the coming year. Soy-based products include glycerine, soaps, paint, linoleum, varnishes, enamel, rubber substitutes, artificial petroleum, and ink.

Soy's principal constituents, isoflavones, bind at estrogen receptor sites. These phytoestrogens, or plant estrogens, are used to treat menopausal symptoms, especially hot flashes, and to help prevent osteoporosis. Soy is also used to inhibit hormone-dependent-especially estrogen-dependent-cancers, such as breast, ovarian, and prostate malignancies. The isoflavones genistein and daidzein block natural estrogen and its potentially harmful effects, while simultaneously giving the benefits of increased estrogen. Products containing 6.25 grams per serving of soy protein are approved by the Food and Drug Administration to help prevent heart disease and lower cholesterol levels. Soybeans are high in nutritional value. They are rich in protein, fiber, and minerals. Soy treats intestinal problems, including constipation and bowel disease, due to its high cellulose content.

Although the soy bean has only a mild medicinal action, it is helpful in stimulating the circulation and acting as a general detoxicant. In Chinese medicine, the sprouts are thought to help relieve "summer heat" and fever.

Habitat & cultivation

Indigenous to east Asia, soy is now cultivated in the United States and Europe.

Constituents

Soy beans contain protein, fixed oil, coumestrol, isoflavones, lecithin, vitamins, and minerals. Coumestrol and the isoflavones closely mimic estrogen within the body.

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