Summary
Food allergy is defined as an adverse immunologic response to a food protein.[1] Although approximately 19% of adults in the US have a perceived adverse reaction to food, only 10.8% have a convincing history of true food allergy, according to a cross-sectional survey study.[2] In a separate study of US households, approximately 11% of children were perceived by their parents to have a food allergy, but only 7.6% had a convincing history of true food allergy.[3]
People who believe they have a food allergy may suffer from a metabolic intolerance to a particular food; for example, lactose intolerance. Others may be sensitive to a particular pharmacologically active component of food such as caffeine or tyramine. Some people may mistake bacterial food poisoning as a reaction to a particular food.[1] Although all of these scenarios involve food, they do not result from an abnormal immune response to a particular food protein and therefore cannot be considered a true food allergy.[4] Rather, some of them, such as lactose intolerance and sucrase-isomaltase deficiency, are considered nonimmune food intolerances, and others, such as tyramine and sulfite reactions, are considered nonimmune food sensitivities.
It is important that people with suspected food allergy are investigated and followed up appropriately so that they do not unnecessarily avoid food and impair their quality of life.[2]
Pathophysiology
Food allergies can be classified into disorders that are immunoglobulin E (IgE)-mediated, cell-mediated, or a combination of the two.[5]
IgE-mediated food allergies result from abnormal sensitization to a food allergen that results in specific IgE production. However, a positive skin prick test or IgE test on its own does not indicate that a patient has a food allergy; it only means that they are sensitized to a food. Only the history or an oral food challenge can identify true food allergens. Once produced, food-specific IgE binds onto mast cells. When the particular food is subsequently ingested, the food is broken down and absorbed. The food antigen then binds to the IgE on the mast cells leading to mast-cell degranulation and release of mediators that cause the signs and symptoms of the allergic reaction.[5] IgE-mediated food disorders include anaphylaxis and oral allergy syndrome.
Cell-mediated reactions involve T cells and may occur several hours to days after ingesting the offending food.[5] Food protein-induced enterocolitis, enteropathy, proctocolitis, and celiac disease are examples of cell-mediated food-allergic diseases.
Mixed IgE- and cell-mediated food diseases include atopic dermatitis and the eosinophilic gastroenteropathies such as eosinophilic esophagitis.[5]
Nonimmune food intolerances often result from deficiencies in the enzyme that breaks down the food component into absorbable substrates in the small intestine.[6]
Nonimmune food sensitivities to biogenic amines (such as tyramine) or to food additives (such as monosodium glutamate) are more controversial and are debated vigorously in the literature.[7][8] However, sensitivities to sulfites found in foods such as red wine and dried fruit have been confirmed as a trigger of bronchospasm in sulfite-sensitive asthmatic patients.[9][Figure caption and citation for the preceding image starts]: Categories of food reactionsSampson HA et al. JACI 2014; 134(5): 1016-1025; used with permission [Citation ends].
Differentials
Common
- Oral allergy syndrome
- Atopic dermatitis
- Food protein-induced allergic proctocolitis (FPIAP)
- Celiac disease
- Lactose intolerance
Uncommon
- Food-induced anaphylaxis
- Food-dependent exercise-induced anaphylaxis
- Eosinophilic esophagitis
- Food protein-induced enterocolitis syndrome (FPIES)
- Congenital sucrase isomaltase deficiency
- Monosodium glutamate (MSG) reactions
- Tyramine reactions
- Sulfite sensitivity
- Galactose-alpha-1,3-galactose (alpha-gal) allergy (tick borne)
Contributors
Authors
Jessica D. Macdougall, MD
Assistant Professor of Medicine, Director of Burghardt Food Allergy Center
Assistant Professor of Medicine, Section of Allergy and Clinical Immunology, School of Medicine
Assistant Professor of Pediatrics, School of Medicine
Oregon Health & Science University
Portland, OR
Disclosures
JDM declares that she has no competing interests.
Acknowledgements
Dr Jessica D. Macdougall would like to gratefully acknowledge Dr J. Andrew Bird, Dr A. Wesley Burks, and Dr Alison Church, previous contributors to this topic.
Disclosures
JAB has received financial compensation for consulting relationships with AllerGenis, DBV Technologies, FARE, Genentech, Hanimune Therapeutics, HAL Allergy, Novartis, and Parexel. His institution has received support for research sponsored by Aimmune Therapeutics, DBV Technologies, FARE, Genentech, NIH/NIAID, Novartis, Regeneron and Siolta. AWB receives grant support to his institution from the National Institutes of Health, and the Burroughs Wellcome Fund; royalties from UpToDate, Elsevier, and Wolters Kluwer; consulting honorariums from Allergy Therapeutics Ltd and DBV Technologies, as well as honorariums from Aimmune Therapeutics, Consortia TX, and Ukko for his service on their respective Scientific Advisory Boards. AWB is an author of references cited in this topic. AC declares that she has no competing interests.
Peer reviewers
Aaron Lerner, MD
Head of Pediatric Gastroenterology and Nutrition Unit
Carmel Medical Center
Haifa
Israel
Disclosures
AL declares that he has no competing interests.
Roy Gerth van Wijk, MD, PhD
Professor of Allergology
Head of Section of Allergology
Department of Internal Medicine
Erasmus Medical Center
Rotterdam
The Netherlands
Disclosures
RGvW declares that he has no competing interests.
Peer reviewer acknowledgements
BMJ Best Practice topics are updated on a rolling basis in line with developments in evidence and guidance. The peer reviewers listed here have reviewed the content at least once during the history of the topic.
Disclosures
Peer reviewer affiliations and disclosures pertain to the time of the review.
References
Key articles
Shaker MS, Wallace DV, Golden DBK, et al. Anaphylaxis-a 2020 practice parameter update, systematic review, and Grading of Recommendations, Assessment, Development and Evaluation (GRADE) analysis. J Allergy Clin Immunol. 2020 Apr;145(4):1082-123.Full text Abstract
Golden DBK, Wang J, Waserman S, et al. Anaphylaxis: a 2023 practice parameter update. Ann Allergy Asthma Immunol. 2024 Feb;132(2):124-76.Full text Abstract
Rubio-Tapia A, Hill ID, Semrad C, et al. American College of Gastroenterology guidelines update: diagnosis and management of celiac disease. Am J Gastroenterol. 2023 Jan 1;118(1):59-76.Full text Abstract
Sampson HA, Aceves S, Bock SA, et al. Food allergy: a practice parameter update-2014. J Allergy Clin Immunol. 2014 Nov;134(5):1016-25.e43.Full text Abstract
Reference articles
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