A food allergy is an immune system response to a food that the body mistakenly believes is harmful, according to the Food Allergy & Anaphylaxis Network.
Once the immune system decides to treat a particular food this way, eating that food can prompt the massive release of chemicals known as histamines. These chemicals, in turn, trigger allergic reactions that can affect the respiratory system, gastrointestinal tract, skin, and cardiovascular system.
Avoiding these foods altogether is the only sure way to prevent a reaction.
Although someone can be allergic to just about any food, the following edibles account for 90 percent of all reactions: milk, eggs, peanuts, tree nuts (including walnuts and cashews), fish, shellfish, soy, and wheat. – (HealthDayNews, updated July 2008)