Food allergies are individualistic adverse reactions, mediated by abnormal responses of the immune system to specific proteins contained in certain foods. Food allergies affect only a small percentage of the population. The symptoms of IgE-mediated food allergies range from mild to severe and life-threatening. Peanuts, tree nuts, crustacean shellfish, fish, milk, eggs, soybeans, and wheat are the most common causes of IgE-mediated food allergies. IgE-mediated food allergies are treated with specific avoidance diets.