Journal of Allergy and Clinical Immunology
9. Food allergy
Section snippets
Pathogenesis
Food allergy might result from a breach in oral tolerance to foods while they are being ingested (class 1 food allergy) or might result from sensitization to allergens apart from their exposure to the gastrointestinal tract, recognized instead during respiratory exposure (class 2 food allergy).11, 12 Class 1 food allergy typically occurs to food proteins that are generally stable to digestion that are encountered by infants or children during a presumed window of immunologic immaturity. In
Clinical disorders
The disorders can be classified on the basis of interrelated immunologic causes and the organ system or systems affected (Table I). The features of each disorder are described in detail in recent reviews.1, 3, 4 Various gastrointestinal food-induced allergic disorders share symptoms but can be differentiated by patterns of illness and diagnostic tests (Table II).1, 24, 25, 26 Additional gastrointestinal symptoms (colic, constipation, and reflux) have sometimes been attributed to food allergy.
Diagnosis
The evaluation begins with a thorough history and physical examination to consider a broad differential diagnosis (Table I). The history should determine the possible causal food or foods, quantity ingested, time course of reaction, ancillary factors (exercise, aspirin, and alcohol), and reaction consistency. Reason dictates that a food ingested infrequently is more likely responsible for an acute reaction than one previously tolerated. Symptoms such as urticaria after ingestion of a food are
Management
The primary therapy for food allergy is to avoid the causal food or foods. New food-labeling laws effective in January 2006 require simple terms to indicate the presence of major food allergens (eg, “milk” instead of “casein”). Patients and caregivers should be encouraged to obtain medical identification jewelry, taught to recognize symptoms, and instructed on using self-injectable epinephrine and activating emergency services. Comprehensive educational materials are available through
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