My wife would be fucked unless this take out some preexisting allergies she has (quinoa, buckwheat, hazelnuts, peanuts, eggs and many legumes including soybeans although she doesn't react to soy lecithin)
I have a soy allergy too and don't react to lecithin. My understanding is that by the time the soy is processed into lecithin, the "thing" you're allergic to is pretty much non-existent and that's why you don't react to it.
This isn't the case for all people who are allergic to soy. This is not medical advice.