You might think that people are kidding around when they tell you they have food allergies. And, it is true that some types of food allergies are only associated with minor symptoms. But others, such as seafood allergies and peanut allergies can be deadly. Fish allergy, in fact, is quite uncommon. Peanut allergy, on the other hand, is becoming, for some unknown reason, increasingly common. Between 1% and 2% of people in the U.S., the U.K. and several other countries are allergic to peanuts. This is roughly triple the rate in the mid-1990s. Although fatal reactions to food allergies are rare, it is important that we learn in minute detail what causes these reactions so that we can intelligently devise effective treatments.