Soy cultivation is believed to have begun in China; Domesticated in northeastern China from the wild Glycine soja, the earliest evidence of cultivation dating to 3000 years ago. The emperor Shen-nong, who compiled the Medical Bible of the Yellow Emperor (Huang-di nei jing) sometime between 2967 and 2597 B.C.E., counted soybean among the five sacred crops. Since then, both ancient Chinese and contemporary Chinese medical literature have claimed health benefits from soy. During the Ming Dynasty (1368~644 B.C.E.), in his 52-volume Chinese Materia Medica, Li-Shi Zhen recommended soybeans for the treatment of kidney disease, edema, and poisoning. Today soy may be recommended for skin diseases, gastrointestinal disorders, leg ulcer, vitamin deficiency, and pregnancy toxemia (Holt, 1996).
The cultigen species Glycine max, known as Soybean, was domesticated in northeastern China from the wild Glycine soja, the earliest evidence of cultivation dating back to 1000 BC. In the third century BC, Soybean and Millet were regarded as the most important food crops in northeastern China. Soybean remains an important source of high protein to people in the Far East and Southeast Asia. From the 1700's, European visitors to the Far East started bringing back Soybean seed to Europe and introducing it to the colonies. Soybean started being grown in the USA from 1765 onwards but it was only in World War II with butter shortages and the need for substitutes that the soybean crops really took off and by 1973, the USA was producing three-quarters of the world crop. Maize farmers found that rotating maize with soybeans reduced the need for nitrogen fertilizers because, being legumes, Soybean have Rhizobium bacteria in their roots that convert gaseous nitrogen to nitrogenous compounds.
Soy, a staple food in many Asian countries, contains valuable constituents, including protein, isoflavones, saponins, and phytosterols. Soy protein provides most of the essential amino acids. It is also low in fat and cholesterol-free.
The isoflavones in soy, primarily genistein and daidzein, have been well researched by scientists for their antioxidant and phytoestrogenic properties. Saponins enhance immune function and bind to cholesterol to limit its absorption in the intestine.
Phytosterols and other components of soy have been reported to lower cholesterol levels.
Isoflavones may reduce the risk of hormone-dependent cancers, such as breast and prostate cancer, as well as other cancers. Both animal and human studies have confirmed this.
