for people who are lucky enough to be allergic to one thing, identifying that one thing and avoiding it may be all it takes.
Aunty gave a lot of time trying to help people. Of course her advice isn't going to work for everyone, and maybe not even most people, but I don't think that is a reason to attack her. Of course she repeats the same story, its her basic experience and advice... why would it change?
i have a hard time understanding why you would want to attack her for this.