I recently listened to an mp3 where it said that soy is dangerous for humans.
The only soy products which are okay is miso (sp?).
I would try to avoid it. I will try to find this mp3 again then you could also listen to it.
I found it. You can download it here:
You don't have to register just click on later and it will download. The soy part starts at: 50:10