Soy

Scientific Name(S): Glycine Max

Common Name(S): Soy, Soybean, Soya

Botany

The soybean plant belongs to the "pea" family, Leguminosae. Legumes are able to transform free nitrogen from the air into a form they can use to grow, providing the bacteria Rhizobium Japonicum is available. The soybean is an annual plant that grows from 1 to 5 feet tall. The bean pods are covered with short, fine hairs, as are the stems and leaves of the plant. The pods contain up to 4 oval seeds, which can be yellow to brownish in color. The cotyledons account for most of the seed's weight, and contain nearly all the oil and protein.

Uses

Soy is commonly used as a source of fiber, protein, and minerals. The isoflavone compounds in soybeans may have anticancer affects, alleviate menopausal symptoms, prevent osteoporosis, and combat cardiovascular and GI problems.

Side Effects

Overall tolerance to soybeans is good to excellent for most patients. Although there are no strong studies, the effects on developmental processes of phytoestrogens in soy-based infant formulas is of concern. Soy dust has caused an asthma epidemic.

History

Soybeans were cultivated in China as far back as the 11th Century BC. Described by Chinese Emperor Shung Nang in 2838 BC, they were said to have been China's most important crop. Cultivation of the plant went to Japan, then Europe, and eventually to the US (in the early 1800s). The US now produces 49% of the world's soybeans. Soybeans possess a number of health benefits, including anticarcinogenic effects, improvement in cardiovascular and intestinal problems, and relief of menopausal symptoms. Soybeans are also an important source of nutrition.

Chemistry

Soybeans are high in nutritional value and can contain up to 25% oil, up to 24% carbohydrate, and up to 50% protein. Isolation of certain proteins and protein determination methods may be used to characterize soybeans and their products. Fatty acids in beans include linoleic (55%), palmitic (9%), stearic (67%), and others. The soybean is also rich in minerals including calcium, iron, and potassium, amino acids, and vitamins. It is also a good fiber source. Soybeans also contain compounds known as isoflavones, structures molecularly similar to natural body estrogens (phytoestrogens). Isoflavonoid analysis has been performed using HPLC-mass spectrometry methods and has proven to be helpful in phytoestrogen and pharmacokinetic research. Constituents genistein, the most abundant isoflavone in soybeans, and daidzein are the focus of most isoflavone research. Radioimmunoassay for daidzein has been recently established. Soybeans, as well as other legumes, are excellent food sources for both of these anticancer metabolites. Glycitein and equol are other isoflavones found in the plant. Isoflavones behave not only as "estrogen mimics," but have other non-hormonal roles as well.

Summary

The soybean is a versatile legume and has been used in Asian populations for thousands of years. They are high in nutritional value and are an excellent source of proteins, vitamins, and minerals. Soybeans contain compounds known as isoflavones, molecularly similar to natural body estrogens. The effects of these "phytoestrogens" are both hormonal and non-hormonal. They may have effects against cancer, may alleviate menopausal symptoms, may prevent osteoporosis, and may combat cardiovascular disease and GI problems. Soy is usually safe, except in individuals who are allergic to it. More research is needed in the areas of its actions on infants consuming soy-based formulas and how it alters thyroid synthesis.