This is another practitioner's experience on soy, thought it was interesting.

http://www.foodrenegade.com/soy-infant-formula-formula-for-disaster/

Soy is something that causes a tremendous amount of pain for those who have IC. After they are through treatment, it is something that if present in small amounts in things it is not so much of a problem, as in soy lecithin, or soy sauce here and there maybe in Asian restaurants kind of thing. But, I would not recommend it regularly, as I do think it is very imbalancing.

In Chinese medicine soy is looked at as very "cold" in nature. When you go outside into the snow, think of how your muscles and body contract. Contracting can cause pain. This is a bit metaphorical but is very relevant. This is another reason why drinking ice cold drinks is not adviseable. But, of course soy is much more complicated than a cold glass of water.

In any case, hope yu find it interesting.

Dr.M & B