FRI FOOD SAFETY REVIEWS What Is Food Allergy?

Introduction Food allergic reactions are due to an immune response to specific food components, allergens, that are commonly glycoproteins or other proteins or, rarely, carbohydrates. The most frequent allergic reactions are immediate hypersensitivity reactions mediated by antibodies (IgE) to food allergens. These antibodies circulate in the blood and are unique in that they can attach to mast cells in the skin, respiratory tract, and gastrointestinal tract, as well as to basophils in the circulation. Mast cells and basophils contain histamine and other substances that produce the signs and symptoms of an allergic reaction: itching, hives, swelling, wheezing, throat constriction, nausea, vomiting, diarrhea, dizziness, loss of consciousness, and, potentially, death from shock (anaphylaxis). When a food allergen interacts with IgE specific to that allergen, the antibodies can trigger a biochemical process in the mast cells and basophils resulting in the release of histamine and other inflammatory substances. These processes occur rapidly, within minutes; thus, the term “immediate hypersensitivity.” In addition to the immediate reaction, some people may also have a so-called “late-phase” reaction that occurs 4 to 6 hours after exposure to the allergen. Other immunologic reactions to foods can occur, such as celiac disease (gluten-sensitivity) and other gastrointestinal diseases that have a delayed onset. Because IgE-mediated allergic reactions can be potentially fatal, this review will focus on these reactions.