Soybean phytoestrogens isoflavones

The phytoestrogens (isoflavones) contain a flavone nucleus. Examples of isoflavones are genistein, formononetin and coumestrol, all with potent estrogenic activity. Soybean isoflavones are a concern in human nutrition because of their estrogenic benefits. 

The three main classes of phytoestrogens (and common food sources) are isoflavones (soybeans), lignans (cereals and oilseeds such as flaxseed), and coumestans (alfalfa sprouts). The biologic potency of phytoestrogens varies and is less than that of synthetic estrogen. 

Soybeans (Glycine max) are protein-rich legumes widely grown around the world as a food crop. They are the major dietary source of isoflavones, which are broken down in the intestine into the phytoestrogens genis-... 

Glycine max (L.) Merrill G. soja Sieb. Zucc. Da Dou Ye Da Dou (Soybean) (seed) Protein, isoflavone derivatives, genisteine, daidzein, riboflavin, thiamine, niacin, pantothenic acid, choline.33,67 Phytoestrogenic, elevate the vasomotor system, prevent cancer, a potent inhibitor of protein tyrosine kinase. 

Isoflavones may be found in small amounts in soy-based infant formulas [10]. Isoflavones are found in whole soybeans and products including tofu, tempeh, and soy milk. Isoflavones are classified as both phytoestrogens (plant estrogens) and selective estrogen receptor modnlators. The phytoestrogenic effects of isoflavones have led to the use of soy foods and isoflavone supplements as alternatives to conventional hormone therapy. However, studies have found no long-term complications associated with isoflavones in infants fed soy-based formulas [10,17]. 

Isoflavones are flavonoids commonly called as phytoestrogens and one of the most extensively investigated polyphenols. These are present in soybeans, soybean products, and other pulses, widely consumed in Asian and Southeast Asian coim-tries. Isoflavones have attracted attention mainly due to their role in the ameliora-ti(Mi of postmenopausal symptoms such as hot flushes and osteoporosis [52,58,59]. The other beneficial and important biological properties have been established which are related to effects on cardiovascular diseases, cognitive functions, and breast and prostate cancers. These conclusions were based on wide-ranging studies and parameters which showed positive effects, for example, reduction of hot flushes, the excretion of Ixme resorption markers, increase in bone mineral density, the lower LDL and total cholesterol, reduction in colon cancer, and modulation of immune function [60, 61]. Chemical structures of some important molecules of these phytochemical classes are represented in Fig. 82.3. 

Isoflavones are a class of phytoestrogens with estrogenic activity. They are related to isoflavonoids. Isoflavones are produced almost exclusively by members of the Fabaceae (Leguminosae) family. Soy products and soybeans are the richest sources of isoflavones that humans consiune [43]. Recent surveys suggest that the average dietary isoflavone intake in Asian countries ranges from 25-50 mg/day [44]. Dietary isoflavone intakes are considerably lower in Western countries, where on average intake is as low as 2 mg/day. Soy products that are... 

Isoflavones have been found in higher concentrations only in the legume family of plants (Fabaceae) and occur in significant amounts only in soybeans and soya bean products. Isoflavones exhibit oestrogenic activity, but also further toxic effects, and are often classified, together with other active compounds, as phytoestrogens (see Section 10.4). 

Brandon, 2001). The individual isoflavones may have different biological activity and certain combination of isoflavones may act synergistically or antagonistically (Rayburn et al., 1995). The presence of other phytoestrogens (biochanin A, coumesterol, and formononetin) in the soybean diet could also influence the results (Kudou et al., 1991). 

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