Food allergy: An overview

Food allergy is an adverse reaction resulting from an inappropriate immunological response to a food antigen. It usually presents as multi-system involvement. Gastrointestinal symptoms, cutaneous symptoms, and respiratory symptoms occur in 50 to 80%, 20 to 40%, and 4 to 25% of cases, respectively. Gastrointestinal manifestations include oral allergy syndrome, gastrointestinal anaphylaxis, allergic eosinophilic esophagitis, allergic eosinophilic gastroenteropathy, food protein-induced enteropathy, food protein-induced enterocolitis syndrome, food protein-induced proctocolitis, gluten-sensitive enteropathy, infantile colic, irritable bowel syndrome, and constipation. Cutaneous manifestations are urticaria/angioedema, atopic dermatitis, contact dermatitis, and dermatitis herpetiformis. Finally, rhinitis/rhinoconjunctivitis, asthma, Heiner syndrome, and serous otitis media are the respiratory manifestations of food allergy. Other manifestations include systemic anaphylaxis, food-dependent exercise-induced anaphylaxis, migraine, epilepsy, diabetes mellitus, nephrotic syndrome, nocturnal enuresis, anemia, thrombocytopenia, vasculitis, and arthropathy/arthritis. Skin-prick testing with food extracts is often used to screen patients with suspected IgE-mediated food allergies. Simultaneously, since many children with IgE-mediated food allergies have elevated serum IgE levels, serum IgE antibodies specific for allergens can be measured in vitro by RAST, ELISA, or FEIA techniques. However, the double-blind placebo-controlled food challenge is objective and is considered the "gold standard" for the diagnosis of a food allergy. Nonetheless, an open or single-blind food challenge is acceptable when the resulting symptoms can be objectively observed. Definitive treatment of food allergy is strict elimination of the offending food from the diet. Symptomatic reactivity to food allergens is generally very specific, and patients rarely react to more than one food in a botanical or animal species. If elimination diets are prescribed, care must be taken to ensure that they are palatable and nutritionally adequate. Patients must have a good knowledge of foods containing the allergen and must be taught to scrutinize the labels of all packaged food carefully. Emergency treatment of food-induced anaphylaxis centers on basic life support principles, and intramuscular injection of epinephrine. A fast-acting H1 antihistamine should be considered for the child with progressive or generalized urticaria or disturbing pruritus. Pharmacological therapies such as mast cell stabilizers have little role in the treatment of food allergy. ©2011 by Nova Science Publishers, Inc. All rights reserved.