Abstract
Based on their nutrient composition, soybeans and related foods have been considered to be nutritious and healthy for humans. Particularly, the biological activity and subsequent benefits of soy products may be associated with the presence of isoflavone in soybeans. As an alternative treatment for menopause-related symptoms, isoflavone has gained much popularity for postmenopausal women who have concerns related to undergoing hormone replacement therapy. However, current research has still not reached a consensus on the effects of isoflavone on humans. This overview is a summary of the current literature about the processing of soybeans and isoflavone types (daidzein, genistein, and S-equol) and supplements and their extraction and analysis as well as information about the utilization of isoflavones in soybeans. The processes of preparation (cleaning, drying, crushing and dehulling) and extraction of soybeans are implemented to produce refined soy oil, soy lecithin, free fatty acids, glycerol and soybean meal. The remaining components consist of inorganic constituents (minerals) and the minor components of biologically interesting small molecules. Regarding the preventive effects on diseases or cancers, a higher intake of isoflavones is associated with a moderately lower risk of developing coronary heart disease. It may also reduce the risks of breast and colorectal cancer as well as the incidence of breast cancer recurrence. Consumption of isoflavones or soy foods is associated with reduced risks of endometrial and bladder cancer. Regarding the therapeutic effects on menopausal syndrome or other diseases, isoflavones have been found to alleviate vasomotor syndromes even after considering placebo effects, reduce bone loss in the spine and ameliorate hypertension and in vitro glycemic control. They may also alleviate depressive symptoms during pregnancy. On the other hand, isoflavones have not shown definitive effects regarding improving cognition and urogenital symptoms. Because of lacking standardization in the study designs, such as the ingredients and doses of isoflavones and the durations and outcomes of trials, it currently remains difficult to draw overall conclusions for all aspects of isoflavones. These limitations warrant further investigations of isoflavone use for women's health.
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