Isoflavones in the aglycone form – as found naturally in fermented soy foods – are more bioavailable than the glucoside-form from non-fermented soy, says a new study from Japan.
Consumption of both types of isoflavone forms by
healthy postmenopausal Japanese women showed that the aglycone-form was
absorbed “faster and in greater amounts”, compared to the glucoside
forms, according to findings published in the Journal of the Science of
Food and Agriculture.
Soy isoflavones are well known phytoestrogens – active substances derived from plants that have a weak estrogen-like action. They have been studied for their role in cancer prevention and slowing down the ageing process in peri-menopausal women, and have proved to be a popular alternative to hormone replacement therapy for those wishing to control menopause symptoms without resorting to drugs.
The new study adds to this body of science, and involved 11 healthy postmenopausal Japanese women aged between 49 and 65. The randomised, double-blind, crossover trial involved giving the women a single dose of fermented or non-fermented soy powder dissolved in hot water. Both interventions provided 95 micromoles of isoflavones per 23 gram serving.
Results showed that the aglycone form reached a maximum blood value much quicker than the glucoside form: one versus five hours, and that the levels were approximately 25 percent greater following consumption of the aglycone form.