Isoflavones and Coumestrol in Soybeans and Soybean Products from Australia and Indonesia

Abstract Phytoestrogens in foods are believed to have a potential benefit in a wide range of human conditions. There are very few data for phytoestrogens in Australian and Indonesian foods. A validated simple rapid isocratic HPLC technique was used to quantify daidzein, genistein, formononetin, biochanin A, and coumestrol in over 60 soybeans and soybean products purchased from retail outlets in Australia and Indonesia. Only daidzein and genistein were found in all soybean products, and none was found in soy sauce. Coumestrol was also found in two soymilks purchased in Indonesia but at biologically significant levels. Within products the levels of daidzein and genistein varied up to six-fold suggesting that these compounds are much less consistent in foods than nutrients are, and implying that derivation of representative levels would be very difficult. The variability was considered to be due to genetic and agricultural factors and not to the method of analysis due to its overall reliability. Processing and preparation did not affect the levels of the compounds in these foods at retail level comparison.