There’s plenty of evidence. Chemically, the isoflavones in soy are phytoestrogens. There is no debate on this point. Nor is there any serious debate that phytoestrogens are Endocrine Disruptor Compounds. http://www.ncbi.nlm.nih.gov/pubmed/21175082
Where it gets complicated is that these phytoestrogens are good for some people at some times in their lives, not good for others (or even the same people at different times).
Here’s a good review of the science. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3074428/
From the Conclusion: “Consumers should be aware that soy contains endocrine disrupting compounds and make dietary choices accordingly. For a typical consumer, alarm over soy products is likely unnecessary but so is the belief that a soy-rich diet will alleviate all ills. Women who are pregnant, nursing, or attempting to become pregnant should use soy foods with caution and be aware that soy formula may not be the best option for their babies.”
