THE DETAILS: The study reviewed existing literature on the prevalence, diagnosis, management, and prevention of food allergies. The authors analyzed 72 studies of food allergies to cow's milk, eggs, peanuts, tree nuts, fish, and shellfish, and came up with some interesting findings.

Most important, there doesn't seem to be a single accepted mode of diagnosing food allergies.

http://health.yahoo.net/rodale/PVN/how-to-know-if-you-have-a-food-allergy