That's a very specific genetic disorder, in which even tradiional staples of vegan diets, like beans and peas, will result in mental retardation, seizures, etc. I don't doubt that affected individuals are healthier if they don't eat any animal products, than if they did (though probably not as healthy as if they didn't have the disorder, and could eat normally). I'd be really surprised if your daughter isn't getting regular dietary supplements of some kind, of synthetic and/or animal origin.
She is.She has to drink a "phe" free formula.It's synthetic.
You'd be surprised how healthy these two are.She's consistantly on A-B honor roll attending private school,also.