Note: the findings in this paper do not constitute prima facie evidence that GM soy is harmful to the health of animals and humans -- but there are very solid grounds for assuming that it might be -- and that is why Monsanto set out, even before this paper was published, to neutralise its effect with a counter study of its own. it only does that sort of thing when it feels threatened by "uncomfortable" results.
"Alterations in Clinically Important Phytoestrogens in Genetically Modified, Herbicide-Tolerant Soybeans"
(Journal of Medicinal Food, (Vol 1., no. 4), July 1999)
by Marc A. Lappé, Ph.D., E. Britt Bailey, M.A., Chandra Childress, M.S., Kenneth D.R. Setchell, Ph.D.,
The growing clinical interest and use of soybean-based food products or extracts to increase dietary phytoestrogen intake makes the precise composition of the key biologically active ingredients of soybeans, notably genistin and daidzin of substantial medical interest. Conventional soybeans are increasingly being replaced by genetically modified varieties. We analyzed the phytoestrogen concentrations in two varieties of genetically modified herbicide tolerant soybeans and their isogenic conventional counterparts grown under similar conditions. An overall reduction in phytoestrogen levels of 12-14 percent was observed in the genetically altered soybean strains. Most of this reduction was attributable to reductions in genistin and to a lesser extent daidzin levels, which were significantly lower in modified compared to conventional soybeans in both strains. Significant sample to sample variability in these two phytoestrogens, but not glycitin, was evident in different batches of genetically altered soybeans. Given the high biological potency of isoflavones and their metabolic conversion products, these data suggest genetically modified soybeans may be less potent sources of clinically relevant phytoestrogens than their conventional precursors. These observations, if confirmed in other soybean varieties, heighten the importance of establishing baselines of expected isoflavone levels in transgenic and conventional soy products to ensure uniformity of clinical results. Disclosure of the origins and isoflavone composition of soy food products would be a valuable adjunct to clinical decision-making.