Examinations should include food allergy tests - Letters to the Editor - Letter to the Editor

Date: Sept 1, 2003

TO THE EDITOR: The article, (1) "Environmental Control of Allergic Diseases," in American Family Physician presents an excellent organized schema for environmental control of common inhalants that contribute to asthma and allergic disease. However, the authors do not mention ingestants that also can trigger reactivity of the respiratory tract. For example, foods induce respiratory symptoms by both reaginic and nonreaginic mechanisms; moreover, food allergies commonly coexist with inhalant allergies. One study (2) showed that 43 percent of asthmatic patients who were placed on a diet that eliminated common allergens substantially improved compared with only 6 percent of subjects in the control group.

A proper diagnosis of specific food allergies often requires screening tests for evidence of food-specific IgE allergy and proof of reactivity through elimination diets and oral food challenges. (3) Double-blind, placebo-controlled food elimination and rechallenge is considered the "gold standard" for diagnosis of food allergies (4) in contrast to skin prick tests and radioallergosorbent tests, which are sensitive indicators of food-specific IgE antibodies but poor predictors of clinical reactivity. (5) In many situations, the diagnosis of food allergy may rest simply on a history of an acute onset of typical symptoms, such as wheezing following the isolated ingestion of a suspected food. (6)

Robert Anderson, M.D.

614 Daniels Dr., N.E

East Wenatchee, WA 98802-4036

REFERENCES

(1.) German JA, Harper MB. Environmental control of allergic diseases. Am Fam Physician 2002;66:421-6.

(2.) Hoj L, Osterballe O, Bundgaard A, Weeke B, Weiss M. A double-blind controlled trial of elemental diet in severe, perennial asthma. Allergy 1981;36:257-62.

(3.) Sampson HA. Food allergy. Part 2: diagnosis and management. J Allergy Clin Immunol 1999;103: 981-9.

(4.) Eigenmann PA, Sampson HA. Interpreting skin prick tests in the evaluation of food allergy in children. Pediatr Allergy Immunol 1998;9:186-91.

(5.) Sampson HA, Ho DG. Relationship between food-specific IgE concentrations and the risk of positive food challenges in children and adolescents. J Allergy Clin Immunol 1997;100:444-51.

(6.) Sicherer SH. Food allergy: when and how to perform oral food challenges. Pediatr Allergy Immunol 1999;10:226-34.

IN REPLY: Dr. Anderson correctly points out that we did not mention in our article (1) that ingestants can trigger reactivity of the respiratory tract. However, the bulk of the literature on this subject indicates that the frequency of significant asthma exacerbation caused by food allergy is low, (2,3) and the vast majority of reactions are caused by a small number of foods such as peanuts, fish, shellfish, eggs, and cow's milk. (4) Persons tend to outgrow allergies to milk and eggs but not to nuts and fish; peanuts are the most common food allergen in children more than three years of age. (4) National and international asthma guidelines recognize that food allergy is an uncommon cause of asthma exacerbation. (3,5) Atopic dermatitis is much more likely than asthma to be caused by food allergy. One study (6) showed that one third of children with refractory atopic dermatitis had clinical reactivity to food proteins.

JEFFREY A. GERMAN, M.D.

MICHAEL B. HARPER, M.D.

Louisiana State University Health Sciences Center

1501 Kings Highway

Shreveport, LA 71130

REFERENCES

(1.) German JA, Harper MB. Environmental control of allergic diseases. Am Fam Physician 2002;66:421-6.

(2.) James JM, Bernhisel-Broadbent J, Sampson HA. Respiratory reactions provoked by double-blind food challenges in children. Am J Respir Crit Care Med 1994;149:59-64.

(3.) National Asthma Education and Prevention Program (National Heart, Lung, and Blood Institute). Guidelines for the diagnosis and management of asthma: expert panel report 2. Bethesda, Md.: U.S. Department of Health and Human Services, Public Health Service, National Institutes of Health, National Heart, Lung, and Blood Institute, 1997;NIH Publication no. 97-4051.

(4.) Rance F, Kanny G, Dutau G, Moneret-Vautrin DA. Food hypersensitivity in children: clinical aspects and distribution of allergens. Pediatr Allergy Immunol 1999;10:33-8.

(5.) Global Initiative for Asthma. National Heart, Lung, and Blood Institute. Global strategy for asthma management and prevention. Bethesda, Md.: U.S. Department of Health and Human Services, Public Health Service, National Institutes of Health, National Heart, Lung, and Blood Institute, 1997; NIH Publication no. 02-3659.

(6.) Eigenmann PA, Sicherer SH, Borkowski TA, Cohen BA, Sampson HA. Prevalence of IgE-mediated food allergy among children with atopic dermatitis. Pediatrics 1998;101:E8.

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