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 25.0ng/ml of daidzein, 94.1ng/ml of genistein, and 9.6ng/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.
aCenter for Community Medicine, Department of Environmental Medicine, Jichi Medical School, 3311-1 Yakushiji, Minamikawachi-machi, Kawachi-gun, Tochigi 329-0498, Japan
bSecond Hospital, Hebei Medical University, Shijiazhuang, China
dCollege of Public Health, Hebei Medical University, Shijiazhang, China
eDepartment of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, Japan
Corresponding author. Center for Community Medicine, Department of Environmental Medicine, Jichi Medical School, 3311-1 Yakushiji, Minamikawachi-machi, Kawachi-gun, Tochigi 329-0498, Japan. Tel.: +81285587336; fax: +81285448465.
☆ Core Research for Evolutionary Science and Technology, Japan Science Technology Corporation (CREST-JST) support this work.
ABSTRACT