My (almost) 3 year old has very bad gluten and dairy (and many other foods) intolerances, so I will be definately put myself on a strict elimination diet throughout my next pregnancy and while breast feeding. Of course it would be important to ensure you are getting enough protein, fats, calcium, etc. from other sources. For us, I would rather do that to give the next baby a chance at not having these intolerances, than deal what we are all going through with both of my kids food intolerance issues.
My pediatrician also recommended that I avoid all nut sources as well if/when I am pregnant again since Ben has a peanut allergy. He’s never had nuts in his life (I’ve been very strict about waiting until he turned 3) and we were quite surprised when testing showed he had a severe peanut allergy. They believe he acquired it when I was pregnant with him and I ate peanut butter.