A food allergy is an immune system response. It occurs when the body mistakes an ingredient in food — usually a protein — as harmful and creates a defense system (antibodies) to fight it. Allergy symptoms develop when the antibodies are battling the “invading” food. The most common food allergies are peanuts, tree nuts (such as walnuts, pecans and almonds), fish, and shellfish, milk, eggs, soy products, and wheat.
