I agree with the previous poster. Also, some foods he may need to avoid would be tomatoes and tomato sauces, cayenne pepper, relish and sweet pickles, lemons and pineapples. Lots of foods, fruits and veggies have citric acid. Some people, however, are able to eat certain foods that have citric acid in them and tolerate them well (even with allergies or their health may deem that type of diet necessary where they should avoid and/or limit citric acid intake). It's really an individual call. It may be wise to have his doc recommend you to a nutritionist to be on the safe side - he or she will be able to recommend a diet plan best suited for your son's needs. Hope he does not feel too bad about it. What is his age (if you do not mind me asking)? Many people on prescribed diets have some of the best meals anyone would want to eat :) This is the time to be creative with your cooking skills - Meals and snacks can still be very enjoyable!!! Best wishes to the both of you.