Soybean

Abstract

Health-promoting effects of soybean seeds are due to the content and type of proteins and polyphenolic compounds (mainly isoflavones). Initial health claim associated with soybean proteins suggested benefits in reducing the incidence and severity of cardiovascular diseases. These health benefits are due to the ability of soybean protein-derived peptides to downregulate hepatic cholesterol synthesis and reduce plasma content of total lipids. The indigestible portion of soybean proteins is believed to entrap cholesterol within the intestinal lumen and prevents reabsorption into the blood circulation. Soybean proteins also increase plasma antioxidant capacity, which reduces lipid oxidation and associated peroxide-induced damage to tissue and organ functions. This is especially the case with soybean protease inhibitors that contain high contents of sulfur groups known to be excellent scavengers of toxic free radicals. Soybean also contains lunasin, which has anticancer properties through its ability to downregulate production of pro-inflammatory cytokines. Soybean isoflavones have estrogen-like structure and may stimulate hormone-induced physiological changes in the body. The isoflavones have beneficial effects in reducing bone mineral loss and may reduce the negative symptoms associated with menopause. Anticancer effects of soybean isoflavones are due to upregulation of apoptotic pathway and suppression of prostaglandin synthesis. In kidney diseases, dietary soybean proteins can induce change in prostanoid synthesis that benefits increase renal vasodilation.