With Miss 0 now at 4 months of age this is something I am about to get into! Yikes!
Click here to read a recent article by Coles Baby and Toddler Club with information from ASCIA regarding when to introduce allergenic foods. I should make clear that the reason I'm avoiding foods in my diet while breastfeeding is not to try to prevent an allergy in Miss 0 but rather because she reacts obviously to the foods via my breastmilk and when I remove them, her skin doesn't break out. I definitely wouldn't avoid a food if it didn't cause a reaction!
I should also say that if there is a history of food allergies in your other kids then you will need to exercise more caution and ensure that you introduce allergenic foods one at a time and probably not as the very first foods. Vegetables and fruits are a good starting point. Be aware that some rice cereals (eg Farex) contain traces of wheat, milk and soy (crazy! I know! Especially because they didn't use to!).
