Food allergy diagnosis and oral food challenge

Food allergy is one of the most common chronic conditions of childhood and one of the most frequently overdiagnosed. The diagnostic challenge is not detecting sensitisation — modern tests do that easily — but separating the child who will react on ingestion from the child who will not. A clinical history that does not fit the test result, or a test result without a supporting history, is the single most common reason for unnecessary dietary restriction, anxiety, and impaired quality of life. The paediatrician who masters the diagnostic pathway protects children both from the danger of a missed allergy and from the harm of a false label. ^[2]

This topic covers the full diagnostic journey: defining and classifying food allergic reactions, interpreting SPT and serum specific IgE with their predictive thresholds, applying component-resolved diagnostics, performing the oral food challenge safely, and navigating the regional guideline landscape from the NIAID consensus to the BSACI and ASCIA frameworks. ^[1][2]

Overview & Definition

A food allergy is an adverse health effect arising from a specific immune response that occurs reproducibly on exposure to a given food. The critical word is immune: this separates food allergy from food intolerance, which is a non-immunological adverse reaction (for example, lactose intolerance from lactase deficiency), and from toxic reactions (for example, scombroid fish poisoning from histamine). ^[1]

The NIAID-sponsored expert panel defined food allergy as "an adverse health effect arising from a specific immune response that occurs reproducibly on exposure to a given food," and the DBPCFC (double-blind placebo-controlled food challenge) as the gold standard for confirming it. Not every food-related symptom is an allergy; not every positive test means a clinical allergy exists. ^[1][2]

The diagnostic process follows a logical chain: first, does the history sound like an allergic reaction? Second, does testing show sensitisation to the implicated food? Third, when history and testing are discordant or inconclusive, does an oral food challenge reproduce symptoms under controlled conditions? Each step has a distinct evidentiary weight, and the paediatrician's job is to integrate them rather than rely on any single test in isolation. ^[5]

References12ShowHide

1. [1]Boyce JA, Assa'ad A, Burks AW, et al. Guidelines for the diagnosis and management of food allergy in the United States: report of the NIAID-sponsored expert panel. J Allergy Clin Immunol, 2010.PMID 21134576
2. [2]Sicherer SH, Sampson HA Food allergy: A review and update on epidemiology, pathogenesis, diagnosis, prevention, and management. J Allergy Clin Immunol, 2018.PMID 29157945
3. [3]Du Toit G, Roberts G, Sayre PH, et al. Randomized trial of peanut consumption in infants at risk for peanut allergy. N Engl J Med, 2015.PMID 25705822
4. [4]Sampson HA, Gerth van Wijk R, Bindslev-Jensen C, et al. Standardizing double-blind, placebo-controlled oral food challenges: American Academy of Allergy, Asthma & Immunology-European Academy of Allergology and Clinical Immunology-PRACTALL consensus report. J Allergy Clin Immunol, 2012.PMID 23195525
5. [5]Foong RX, Dantzer JA, Wood RA, et al. Improving Diagnostic Accuracy in Food Allergy. J Allergy Clin Immunol Pract, 2021.PMID 33429723
6. [6]Togias A, Cooper SF, Acebal ML, et al. Addendum guidelines for the prevention of peanut allergy in the United States: Report of the National Institute of Allergy and Infectious Diseases-sponsored expert panel. Ann Allergy Asthma Immunol, 2017.PMID 28065802
7. [7]Chan JCK, Peters RL, Koplin JJ, et al. Food Challenge and Community-Reported Reaction Profiles in Food-Allergic Children Aged 1 and 4 Years: A Population-Based Study. J Allergy Clin Immunol Pract, 2017.PMID 28283159
8. [8]Peters RL, Allen KJ, Dharmage SC, et al. Natural history of peanut allergy and predictors of resolution in the first 4 years of life: A population-based assessment. J Allergy Clin Immunol, 2015.PMID 25725989
9. [9]Stiefel G, Anagnostou K, Boyle RJ, et al. BSACI guideline for the diagnosis and management of peanut and tree nut allergy. Clin Exp Allergy, 2017.PMID 28836701
10. [10]Perkin MR, Logan K, Marrs T, et al. Enquiring About Tolerance (EAT) study: Feasibility of an early allergenic food introduction regimen. J Allergy Clin Immunol, 2016.PMID 26896232
11. [11]Spolidoro GCI, Ali MM, Amera YT, et al. Prevalence estimates of eight big food allergies in Europe: Updated systematic review and meta-analysis. Allergy, 2023.PMID 37405695
12. [12]Leonard SA, Pecora V, Fiocchi AG, et al. Food protein-induced enterocolitis syndrome: a review of the new guidelines. World Allergy Organ J, 2018.PMID 29441147