Posted by Chantel M.
In study of "Effect of soy isoflavone supplementation on markers of oxidative stress in men and women." by Djuric Z, Chen G, Doerge DR, Heilbrun LK, Kucuk O., according to the researchers, Blood samples were obtained at weekly intervals for 3 weeks from the women taking 50-mg isoflavones once daily and the men taking 50-mg isoflavones twice daily. Plasma levels of genistein and daidzein increased after supplementation with maximal levels occurring at 2 weeks for the women while levels in men kept increasing over the 3 weeks of study. There was wide variation between individuals in the levels of isoflavones achieved. Mean levels of 5-hydroxymethyl-2'-deoxyuridine (5-OHmdU) in DNA from nucleated blood cells decreased after 1 week of supplementation in the women, with a decrease of 47% in mean 5-OHmdU levels after 3 weeks. In men, mean 5-OHmdU levels did not decrease until after 3 weeks of supplementation, at which there was 61% decrease. Mean plasma levels of 8-isoprostanes were not changed appreciably in either men or women.
They conclude that These pilot results suggest that soy isoflavone supplementation decreases levels of oxidative DNA damage in humans, and this may be a mechanism behind the cancer-preventive effects of soy isoflavones.
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