ELISA as a new method to measure genistein and daidzein in food and human fluids

Widely distributed in the plant kingdom, phytoestrogens, like soy isoflavones are found in plant protein extracts at varying levels depending on culture conditions and cultivars. Their increasingly used in human, as natural estrogens and their varying levels in raw materials raise the question concerning the measurement of isoflavones both in food or food supplements as well as in human fluid. To validate our new ELISA technique, isoflavones measurements in food-supplements, in soy food and in human fluid from volunteers participating to a kinetic study or a survey, were done. Our method was also compared with other physico-chemical techniques in an inter-laboratory assay (23 laboratories). In conclusion, our new ELISA technique is reliable, sensitive, cheap, rapid and can be used either for a great number of human fluid analysis, for crude matter or food analysis as long as the appropriate extraction technique is performed prior to ELISA procedure.