Identification of equol producers in a Japanese population by high-performance liquid chromatography with coulometric array for determining serum isoflavones☆
Abstract
Using a method of high-performance liquid chromatography (HPLC) with coulometric array, we measured isoflavone levels in sera from seven volunteers before and after three days of ingesting Soyaflavone E (an isoflavones powder) and from 129 female farmers (Japanese Multiple Environmental Toxicants Study; JMETS). Results showed that the serum isoflavone concentrations rose dramatically after three days of ingesting Soyaflavone E in all subjects except for the serum equol concentrations in two subjects. The geometric mean concentrations of daidzein, genistein, and equol in the serum of 129 Japanese women were 25.0
ng/ml of daidzein, 94.1
ng/ml of genistein, and 9.6
ng/ml of equol. Interestingly, there existed two dominant groups in terms of serum equol concentrations in an independent manner of soy-derived product intake among the study participants.
Keywords: Isoflavone, HPLC coulometric array, Human serum, Equol producer, JMETS project
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☆ Core Research for Evolutionary Science and Technology, Japan Science Technology Corporation (CREST-JST) support this work.
PII: S0944-7113(05)00208-4
doi:10.1016/j.phymed.2005.09.013
© 2005 Elsevier GmbH. All rights reserved.
