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Chapter 1 : Clinical Manifestations of Food Allergic Disease
Adverse reactions to foods are classified as either food hypersensitivity (allergy) or food intolerance. IgE-mediated hypersensitivity accounts for the majority of well-characterized food allergic reactions, although non-IgE-mediated immune mechanisms are believed to be responsible for a variety of hypersensitivity disorders. This chapter examines adverse food reactions that are IgE mediated and non-IgE mediated and those entities that have characteristics of both. The true prevalence of adverse food reactions is still unknown. The vast majority of food allergic reactions are secondary to a limited number of foods. Oral tolerance to food allergens occurs as the result of an appropriate suppression of the immune system when the gut mucosa comes in contact with dietary proteins. Gastrointestinal clinical manifestations are generally milder, and histologic examination of the gut mucosa shows less-extensive changes than with those patients presenting with primary gastrointestinal disease. Celiac disease is an extensive enteropathy leading to malabsorption. Once the diagnosis of food allergy is established, the only proven therapy is the strict elimination of the food from the patient’s diet. Certain factors place some individuals at increased risk for more severe anaphylactic reactions: (i) history of a previous anaphylactic reaction; (ii) history of asthma, especially if poorly controlled; (iii) allergy to peanuts, nuts, fish, and shellfish; (iv) use of ß-blockers or angiotensin-converting enzyme inhibitors; and (v) (possibly) being female. Primary prevention of food allergies relates to blocking immunologic sensitization to foods. Patient education and support are essential for food-allergic patients.