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Food allergies, defined as adverse immune responses to food proteins, are an increasingly common concern in pediatrics. Food allergy is very distinct from food intolerance, which is defined as a nonimmune reaction that includes metabolic, toxic, pharmacologic, and undefined mechanisms. Food allergy is not one disease but a spectrum of clinicopathologic disorders. As such, manifestations of food allergies differ significantly, depending on the immune mechanism involved and the affected target organ, and range from the prototypical symptoms of acute urticaria/angioedema to chronic conditions such as eczema or eosinophilic gastrointestinal disease. The severity of a food allergic reaction may vary with similar exposures and even in the same individual. As a whole, fatalities are rare, but they do occur. Teenagers are particularly vulnerable because they are risk takers and, therefore, may ignore warning signs of an impending severe reaction.
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Because a diagnosis of food allergy causes a considerable nutritional and social burden for affected children and their families, all efforts should be geared to ensure that a true food allergy is the reason for a patient’s symptoms. This identification is not an easy task, given the protean clinical manifestations of these disorders and the recognized pitfalls of the routine laboratory tests. In some instances, a double, blind placebo-controlled food challenge (DBPCFC) may be necessary. This time-consuming procedure is at present the only gold standard test for the diagnosis of food allergy.
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Whereas many children will outgrow their food allergies, for others, it will remain a lifelong concern. The natural history of disease depends on the food, the patient’s age, the pathophysiology of the allergy and, for many foods, is not well defined. Typically, children outgrow milk, egg, wheat, and soy allergies, but allergies to nuts, shellfish, and fish are persistent. Some allergens are heat-labile, and others are heat-resistant. For instance, most children with milk and egg allergies can tolerate extensively baked foods containing the allergen, but peanut allergenicity is not altered by baking. For the vast majority of food allergies, there are no curative treatments. Current management of these conditions relies on careful avoidance of the offending food(s) and initiating therapy to treat symptoms after accidental exposures. There have been recent clinical trials of allergen-specific immunotherapy in the treatment of food allergies and discovery of introductory feeding practices that influence the development of food allergies. These prevention and treatment strategies may be important in future management of children at risk for food-allergy reactions.
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Food allergies are prevalent globally, but the rates vary widely in different countries. Estimates of the burden of food allergies depend on the method of diagnosis, with self-report overestimating the true prevalence. As many as one-fourth of the general population may report food-allergic disease, but true food allergy occurs in 1% to 10% of children. In the United States, the overall prevalence of food allergies has been estimated in 3% of the general population, ...