Hi Nai,
I have been visiting a website that has info about allergies. I can send it to you if you'd like. It did cost money to join, but Im not sure if you'd have to pay to just look (I don't think you do).
Anyway the women on there are mainly american and their kids have some horrific allergies. The general response has been that there's no proof that avoiding the allergen will help. However, I have been advised to avoid what DD is allergic to (but not be ridiculous, if I eat something with egg or nut, not to worry) and was also told to avoid shellfish due to it's severity in reactions. Then one woman said to eat in moderation (seriously I do binge on things) and rotate what I eat, particularly in 3rd tri.
I also remember at a first aid course a couple of years ago that the woman taking the class swears that allergies come from what you eat in Third tri, so I am thinking there is some truth in that (I ate so many eggs and lots of thai in 3rd tri). So during that time I will definitely be avoiding. I think also whilst bf as well.
Hope that helps...xoxox