![]() Significant amino acid sequence homology and a resulting high rate of clinical cross-reactivity between milk from ruminants (eg, approximately 90 percent of children with IgE-mediated CMA react to goat's milk) make milk from sheep and goats inappropriate feeding alternatives for most persons with CMA. Studies of in vitro assays and skin prick testing have shown extensive cross-reactivity between milk from cows, sheep (ewe), goats, buffalo, deer, and ibex (wild mountain goat) but only weak cross-reactivity with proteins from donkeys, mares, and reindeer and no significant cross-reactivity to camel's and pig's milk. Grains, fruits, vegetables, and legumes are less cross-reactive, and evaluation/individualization is generally recommended to expand the diet.ĬOW'S MILK - Most of the mammalian milks or milk products that are commonly consumed, such as those from sheep or goat, will trigger allergic reactions in a person with cow's milk allergy (CMA).Caution and possible allergy testing (including oral food challenges) are warranted if ingestion of related foods not already tolerated is being considered. Tree nuts, fish, and shellfish are more commonly clinically cross-reactive. ![]() Further evaluation is generally not needed if a related food is already ingested routinely without reactions. In these cases, it may be reasonable to evaluate the patient for allergy to the related food to determine clinical tolerance, depending upon epidemiologic, social, and nutritional consequences and concerns. Approximate rates of clinical cross-reactivity are summarized in the figure ( figure 1).Ĭoncern about allergy can arise if a related food was never ingested or was not a regular part of the diet and was not recently ingested. ![]() Thus, a person with an allergy to peanut (a legume) is likely to have "positive" serum immunoglobulin E (IgE) tests or skin prick tests to multiple legumes that are clinically tolerated (see 'Legume cross-reactivity' below). However, a "positive" allergy test to a related food may simply represent immunologic vers-reactivity due to the presence of a homologous protein that does not have clinical significance, which is more common than true clinical cross-reactivity. OVERVIEW OF CROSS-REACTIVITY - When a patient has a confirmed allergy to one food, evaluation of related foods may be indicated to determine if these foods are also problematic. The clinical characteristics, diagnosis, and management of specific food allergies are also discussed in detail separately. (See "Molecular features of food allergens" and "Diagnostic evaluation of IgE-mediated food allergy" and "Management of food allergy: Avoidance" and "Food allergy in children: Prevalence, natural history, and monitoring for resolution" and "Pathogenesis of oral allergy syndrome (pollen-food allergy syndrome)".) Other topic reviews discuss molecular aspects of food allergens, evaluation of food allergies, avoidance of food allergens, the natural history of food allergy, and oral allergy syndrome. INTRODUCTION - This topic reviews clinically relevant features regarding food allergen cross reactivity.
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