As for allergies, these things are at the most common food allergies: milk egg peanut tree nut (walnut, cashew, etc.) fish, shellfish soy wheat so those are the things we have been most cautions about introducing. Most allergies are 'born' when large food particles penetrate the intestinal lining and enter the body undigested, prompting a reaction. This often happens in kids younger than 6 months because their digestive system is more permiable to foods, after 6 months it's harder for this to happen, though when the kid is sick they may once again become more succeptable. Anyway (with the exception of egg yolk since there is so much good stuff in it) we've been pretty cautious about the above foods, giving only small amounts at a time and watching for a reaction. I think the 'dont add salt, fat or sugar' is PC nonsense and is way off base. Salt is required to live and there has never been any evidence that it's harmfull to babys. And breastmilk is extremly high in saturated fat and sugar, so I dont think mother nature pays much attention to the above guideline either.