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Journal of Toxicology
Volume 2009 (2009), Article ID 307618, 13 pages
Research Article

Developmental and Reproductive Effects of SE5-OH: An Equol-Rich Soy-Based Ingredient

1Burdock Group, Orlando, FL 32801, USA
2The Safety Assessment Division II, Mitsubishi Chemical Safety Institute Ltd., Tokyo 105-0014, Japan
3The Department of Toxicology, Otsuka Pharmaceutical Co. Ltd., Tokushima 771-0192, Japan
4The Saga Nutraceuticals Research Institute, Otsuka Pharmaceutical Co. Ltd., Tokushima 771-0192, Japan

Received 29 May 2008; Revised 7 August 2008; Accepted 7 October 2008

Academic Editor: Robert Tanguay

Copyright © 2009 Ray A. Matulka et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Consumption of the isoflavones daidzein, genistein, glycitein, and their structural analogues is generally considered beneficial to human health. Equol is not found in soy, but is converted from daidzein by human gut bacterial flora. Research indicates that between 30–50% of the population is capable of converting daidzein to equol; therefore, there has been recent development of a new equol-rich functional food that relies on bacterial conversion of daidzein to equol under strictly controlled conditions. Therefore, a new equol-rich soy product (SE5-OH) has been developed, based on the bacterial conversion of daidzein; and its reproductive and developmental toxicity has been evaluated in a two-generation study and a developmental toxicity study with Sprague-Dawley rats at dose levels of 200, 1000, and 2000 mg/kg/day by gavage. SE5-OH contains approximately 0.65% equol, 0.024% daidzein, 0.022% genistein, and 0.30% glycitein. From the reproductive study, the no-observed-adverse-effect-level (NOAEL) for SE5-OH determined for both male and female rats is 1000 mg/kg/day (6.5 mg equol/kg/day). In the developmental toxicity phase of the study, no effects by SE5-OH were found in the embryo-fetus at any of the doses tested. The NOAEL for developmental effects of SE5-OH is 2000 mg/kg/day (13 mg equol/kg/day).