Daidzein: bioavailability, potential for reproductive toxicity, and breast Cancer chemoprevention in female rats

Soy products containing phytoestrogens have received much attention as dietary components to promote better health. Daid-zein, an isoflavone and phytoestrogen component of soy, was investigated for its potential to alter fertility and cause develop-mental toxicity to the reproductive tract in female rats, for che-moprevention to the mammary gland, and to study its bioavail-ability. Diets containing 0 mg, 250 mg (low dose), and 1000 mg (high dose) daidzein/kg feed were fed to virgin female rats, starting 2 weeks prior to breeding and continued until the offspring were 50 days postpartum. The serum daidzein concentrations in adult female rats fed the low and high daidzein-containing diets were determined to be 6- and 13-fold higher than serum daidzein concentrations of Asians eating a traditional diet high in soy. Both daidzein doses had no significant effect on fertility, numbers of male and female offspring, and anogenital distances. The high, bu