The guides will certainly try their best to make sure everyone is accommodated, but depending on the location of the trip it may be challenging. I'm sure that you can find foods that don't contain those items, but I would be concerned about cross-contamination depending on how bad the allergy is. Many of the meals are buffet. I have a shellfish allergy and have been mostly ok on our trips, but did have a problem at our lovely hotel in Peru, which I believe was due to cooking my meal with the same grill or pan used for shellfish. That being said, I haven't let it stop me from taking the trips, I'm just a little more cautious about what I choose. I would call and ask the vacationistas how they can handle those allergies on the specific trips you are looking into.