Food Allergies

Food allergy represents a rapidly growing public health problem in the United States and other westernized nations. Adverse reactions to foods are categorized as either immunologic or nonimmunologic reactions. This distinction is highly important but often confusing to patients and physicians unfamiliar with allergy, who may simply describe any adverse reaction to a food as an “allergy.” A food allergy is an immune-mediated, adverse reaction to one or more protein allergens in a particular food item involving recognition of that protein by specifically targeted IgE or allergen-specific T cells. This chapter discusses the definition, pathophysiology, epidemiology, testing, management, prognosis, and natural history of food allergy. Clinical manifestations are systematically covered, including cutaneous, respiratory, cardiovascular, and gastrointestinal reactions, as well as eosinophilic esophagitis, food protein–induced enterocolitis syndrome, and oral allergy syndrome. Emerging treatments such as food oral immunotherapy are also reviewed. Tables outline signs and symptoms of immediate hypersensitivity reactions to food, the prevalence of major food allergens in the United States, common patterns of cross-reactivity among foods, clinical criteria for the diagnosis of anaphylaxis, and clinical studies involving treatment for food allergies. Figures illustrate the classification of adverse reactions to food, esophageal histology, visual and radiographic features of eosinophilic esophagitis, and a food allergy action plan. This review contains 4 figures, 8 tables, and 64 references. KeyWords: Food allergy, Hypersensitivity, IgE-mediated allergy, Eosinophilic esophagitis, Anaphylaxis