Food Allergies Make an Appointment Find a Doctor Ask a Question Reviewed by Bruce J. Lanser, MD (August 01, 2015) An allergic reaction to a food is an unpleasant reaction caused by the immune system overreacting to a food. The most common type of food allergy is caused by an overly sensitive immune system that creates IgE antibodies directed against an otherwise harmless protein in the food (allergens). Unpleasant reactions to foods not caused by the immune system are considered to be food intolerances. Food intolerances have various causes. For example, a person may lack an enzyme needed to digest a portion of a certain food (e.g. lactose intolerance) or the food may be contaminated by bacterial or other toxins that cause symptoms resembling those of food allergy (e.g. food poisoning). Food Allergy Prevalence Since so many people have a negative reaction to a food at some time in their lives, the public perception of the prevalence of food allergy is skewed. In reality, very few people are truly allergic to foods. It is estimated that eight percent of young children and three to four percent of adults have food allergies. However, for those who are allergic, it is important to diagnose the allergy and identify the food so that serious, and even life-threatening, reactions can be avoided. Most Common Food Allergies Children Adults Eggs Peanuts Milk Tree Nuts* Peanuts Fish Tree Nuts* Shellfish** Soy Wheat Fish Shellfish** *Tree nuts include almond, Brazil nut, cashew, hazelnut, macadamia nut, pecan, pine nut, pistachio and walnut **Shellfish can include crustaceans (e.g. shrimp, lobster, crab) and mollusks (e.g. scallops, clams). Programs & Services Allergy Treatment Programs (Adult) Clinical Trials For more than 100 years, National Jewish Health has been committed to finding new treatments and cures for diseases. Search our clinical trials.