View source for Food allergy

{{short description|Hypersensitivity reaction to a food}}
{{Use dmy dates|date=September 2019}}

{{Infobox medical condition (new)
| name            = Food allergy
| image           = Hives on back.jpg
| caption         = [[Hives]] on the back are a common allergy symptom.
| field           = [[Emergency medicine]], [[allergy and immunology]]
| symptoms        = [[pruritus|Itchiness]], swelling of the tongue, vomiting, diarrhea, hives, trouble breathing, low blood pressure<ref name=NIH2012pdf/>
| complications   =
| onset           = Minutes to several hours of exposure<ref name=NIH2012pdf/>
| duration        = Long term, some may resolve<ref name=Sic2014/>
| types           =
| causes          = [[immune system|Immune response]] to [[food]]<ref name=NIH2012pdf/>
| risks           = Family history, [[vitamin D deficiency]], [[obesity]], high levels of cleanliness<ref name=NIH2012pdf/><ref name=Sic2014/>
| diagnosis       = Based on a [[medical history]], [[elimination diet]], [[skin prick test]], [[oral food challenge]]<ref name=NIH2012pdf/><ref name=Sic2014/>
| differential    = [[Food intolerance]], [[celiac disease]], [[food poisoning]]<ref name=NIH2012pdf/>
| prevention      = Early exposure to potential allergens,<ref name=Sic2014/><ref name=Ie2016/> [[omalizumab]]
| treatment       = Avoiding the food in question, having a plan if exposure occurs, [[medical alert jewelry]]<ref name=NIH2012pdf/><ref name=Sic2014/>
| medication      = [[Adrenaline]] (epinephrine)<ref name=NIH2012pdf/>
| prognosis       =
| frequency       = ~6% (developed world)<ref name=NIH2012pdf/><ref name=Sic2014/>
| deaths          =
}}

<!-- Definition and symptoms -->
A '''food allergy''' is an abnormal [[immune system|immune response]] to [[food]]. The symptoms of the allergic reaction may range from mild to severe. They may include [[pruritus|itchiness]], swelling of the tongue, [[vomiting]], diarrhea, hives, trouble breathing, or low blood pressure. This typically occurs within minutes to several hours of exposure. When the symptoms are severe, it is known as [[anaphylaxis]].<ref name=NIH2012pdf/> A [[food intolerance]] and [[food poisoning]] are separate conditions, not due to an immune response.<ref name=NIH2012pdf/><ref>{{cite journal | vauthors = Boyce JA, Assa'ad A, Burks AW, Jones SM, Sampson HA, Wood RA, Plaut M, Cooper SF, Fenton MJ, Arshad SH, Bahna SL, Beck LA, Byrd-Bredbenner C, Camargo CA, Eichenfield L, Furuta GT, Hanifin JM, Jones C, Kraft M, Levy BD, Lieberman P, Luccioli S, McCall KM, Schneider LC, Simon RA, Simons FE, Teach SJ, Yawn BP, Schwaninger JM | display-authors = 6 | title = Guidelines for the Diagnosis and Management of Food Allergy in the United States: Summary of the NIAID-Sponsored Expert Panel Report | journal = The Journal of Allergy and Clinical Immunology | volume = 126 | issue = 6 | pages = 1105–1118 | date = December 2010 | pmid = 21134568 | pmc = 4241958 | doi = 10.1016/j.jaci.2010.10.008 }}</ref>

<!-- Cause, mechanism, and diagnosis -->
Common foods involved include [[cow's milk]], [[peanut]]s, [[egg as food|eggs]], [[shellfish]], [[fish as food|fish]], [[tree nuts]], [[soybean|soy]], [[wheat]], and [[sesame]].<ref name="NIH2012pdf" /><ref>{{cite journal | vauthors = Sicherer SH, Sampson HA | title = Food allergy: A review and update on epidemiology, pathogenesis, diagnosis, prevention, and management | journal = The Journal of Allergy and Clinical Immunology | volume = 141 | issue = 1 | pages = 41–58 | date = January 2018 | pmid = 29157945 | doi = 10.1016/j.jaci.2017.11.003 | doi-access = free }}</ref><ref name="Sic2014" /><ref name="No2015">{{cite journal | vauthors = Nowak-Węgrzyn A, Katz Y, Mehr SS, Koletzko S | title = Non-IgE-mediated gastrointestinal food allergy | journal = The Journal of Allergy and Clinical Immunology | volume = 135 | issue = 5 | pages = 1114–1124 | date = May 2015 | pmid = 25956013 | doi = 10.1016/j.jaci.2015.03.025 | doi-access = free }}</ref> The common allergies vary depending on the country.<ref name="NIH2012pdf" /> Risk factors include a family history of [[allergies]], [[vitamin D deficiency]], [[obesity]], and high levels of cleanliness.<ref name=NIH2012pdf/><ref name=Sic2014/> Allergies occur when [[immunoglobulin E]] (IgE), part of the body's immune system, binds to food molecules.<ref name=NIH2012pdf/> A [[protein]] in the food is usually the problem.<ref name=Sic2014/> This triggers the release of inflammatory chemicals such as [[histamine]].<ref name=NIH2012pdf/> Diagnosis is usually based on a [[medical history]], [[elimination diet]], [[skin prick test]], blood tests for food-specific IgE [[antibodies]], or [[oral food challenge]].<ref name=NIH2012pdf/><ref name=Sic2014/>

<!-- Prevention, treatment, and prognosis -->
Management involves avoiding the food in question and having a plan if exposure occurs.<ref name=Sic2014/> This plan may include giving [[adrenaline]] (epinephrine) and wearing [[medical alert jewelry]].<ref name=NIH2012pdf/> Early childhood exposure to potential allergens may be protective against later development of a food allergy.<ref name=Sic2014/><ref name=Ie2016>{{cite journal | vauthors = Ierodiakonou D, Garcia-Larsen V, Logan A, Groome A, Cunha S, Chivinge J, Robinson Z, Geoghegan N, Jarrold K, Reeves T, Tagiyeva-Milne N, Nurmatov U, Trivella M, Leonardi-Bee J, Boyle RJ | display-authors = 6 | title = Timing of Allergenic Food Introduction to the Infant Diet and Risk of Allergic or Autoimmune Disease: A Systematic Review and Meta-analysis | journal = JAMA | volume = 316 | issue = 11 | pages = 1181–1192 | date = September 2016 | pmid = 27654604 | doi = 10.1001/jama.2016.12623 | hdl-access = free | hdl = 10044/1/40479 }}</ref> The benefits of [[allergen immunotherapy]] for treating food allergies are not proven, thus not recommended {{as of|2015|lc=yes}}.<ref name=NIH2015Imm>{{cite web|title=Allergen Immunotherapy|url=https://www.niaid.nih.gov/topics/allergicdiseases/Pages/allergen-immunotherapy.aspx|access-date=15 June 2015|date=April 22, 2015|url-status=dead|archive-url=https://web.archive.org/web/20150617122922/http://www.niaid.nih.gov/topics/allergicdiseases/Pages/allergen-immunotherapy.aspx|archive-date=17 June 2015}}</ref> Some types of food allergies among children resolve with age, including those to milk, eggs, and soy; while others such as to nuts and shellfish typically do not.<ref name=Sic2014/>

<!-- Epidemiology and culture -->
In the [[developed world]], about 4% to 8% of people have at least one food allergy.<ref name=NIH2012pdf>{{cite web|author1=National Institute of Allergy and Infectious Diseases |title=Food Allergy An Overview |url=https://www.niaid.nih.gov/topics/foodAllergy/Documents/foodallergy.pdf|date=July 2012|url-status=dead|archive-url=https://web.archive.org/web/20160305145206/http://www.niaid.nih.gov/topics/foodallergy/documents/foodallergy.pdf|archive-date=2016-03-05}}</ref><ref name=Sic2014>{{cite journal | vauthors = Sicherer SH, Sampson HA | title = Food allergy: Epidemiology, pathogenesis, diagnosis, and treatment | journal = The Journal of Allergy and Clinical Immunology | volume = 133 | issue = 2 | pages = 291–307; quiz 308 | date = February 2014 | pmid = 24388012 | doi = 10.1016/j.jaci.2013.11.020 }}</ref> They are more common in children than adults and appear to be increasing in frequency.<ref name=Sic2014/> Male children appear to be more commonly affected than females.<ref name=Sic2014/> Some allergies more commonly develop early in life, while others typically develop in later life.<ref name=NIH2012pdf/> In developed countries, more people believe they have food allergies when they actually do not have them.<ref>{{cite web|title=Making sense of allergies|url=http://www.senseaboutscience.org/data/files/resources/189/Making-Sense-of-Allergies.pdf|page=1|publisher=Sense About Science|access-date=7 June 2015|url-status=dead|archive-url=https://web.archive.org/web/20150618155222/http://www.senseaboutscience.org/data/files/resources/189/Making-Sense-of-Allergies.pdf|archive-date=18 June 2015}}</ref><ref>{{cite journal | vauthors = Coon ER, Quinonez RA, Moyer VA, Schroeder AR | title = Overdiagnosis: how our compulsion for diagnosis may be harming children | journal = Pediatrics | volume = 134 | issue = 5 | pages = 1013–1023 | date = November 2014 | pmid = 25287462 | doi = 10.1542/peds.2014-1778 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Ferreira CT, Seidman E | title = Food allergy: a practical update from the gastroenterological viewpoint | journal = Jornal de Pediatria | volume = 83 | issue = 1 | pages = 7–20 | year = 2007 | pmid = 17279290 | doi = 10.2223/JPED.1587 | doi-access =  }}</ref>
{{TOC limit|3}}

== Signs and symptoms ==
[[File:Signs and symptoms of anaphylaxis.png|400px|right|Signs and symptoms of anaphylaxis]]
Food allergy symptoms occur within minutes to hours after exposure and may include:<ref name=medlineplus>{{MedlinePlusEncyclopedia|000817|Food allergy}}</ref>
* [[Rash]]
* [[Hives]]<ref name=medlineplus/>
* Itching of mouth, lips, tongue, throat, eyes, skin, or other areas<ref name=medlineplus/>
* Swelling ([[angioedema]]) of lips, tongue, eyelids, or the whole face<ref name=medlineplus/>
* Difficulty swallowing<ref name=medlineplus/>
* Runny or congested nose<ref name=medlineplus/>
* Hoarse voice<ref name=medlineplus/>
* [[Wheezing]] and/or shortness of breath<ref name=medlineplus/>
* Diarrhea, abdominal pain, and/or stomach cramps<ref name=medlineplus/>
* Lightheadedness<ref name=medlineplus/>
* Fainting<ref name=medlineplus/>
* Nausea<ref name=medlineplus/>
* Vomiting<ref name=medlineplus/>

In some cases, however, onset of symptoms may be delayed for hours.<ref name=medlineplus/>

Symptoms can vary. The amount of food needed to trigger a reaction also varies.<ref>{{cite journal | vauthors = Simons FE, Ardusso LR, Bilò MB, El-Gamal YM, Ledford DK, Ring J, Sanchez-Borges M, Senna GE, Sheikh A, Thong BY | display-authors = 6 | title = World allergy organization guidelines for the assessment and management of anaphylaxis | journal = The World Allergy Organization Journal | volume = 4 | issue = 2 | pages = 13–37 | date = February 2011 | pmid = 23268454 | pmc = 3500036 | doi = 10.1097/WOX.0b013e318211496c }}</ref>

Serious danger regarding allergies can begin when the respiratory tract or blood circulation is affected. The former can be indicated through wheezing and [[cyanosis]]. Poor blood circulation leads to a weak [[pulse]], pale skin and [[fainting]].<ref>van Ree 1</ref>

A severe case of an allergic reaction, caused by symptoms affecting the respiratory tract and blood circulation, is called [[anaphylaxis]].  When symptoms are related to a drop in blood pressure, the person is said to be in [[anaphylactic shock]]. Anaphylaxis occurs when [[IgE antibodies]] are involved, and areas of the body that are not in direct contact with the food become affected and show symptoms.<ref>{{harvnb|Sicherer|2006|p=12}}</ref> Those with [[asthma]] or an allergy to peanuts, tree nuts, or seafood are at greater risk for anaphylaxis.

==Causes==

=== Common food allergies ===
Allergic reactions are abnormal immune responses that develop after exposure to a given food allergen.<ref name="Sicherer-2018">{{cite journal | vauthors = Sicherer SH, Sampson HA | title = Food allergy: A review and update on epidemiology, pathogenesis, diagnosis, prevention, and management | language = English | journal = The Journal of Allergy and Clinical Immunology | volume = 141 | issue = 1 | pages = 41–58 | date = January 2018 | pmid = 29157945 | doi = 10.1016/j.jaci.2017.11.003 | doi-access = free }}</ref> Food allergens account for about 90% of all allergic reactions.<ref>{{Cite web |date=2013-12-09 |title=Food Allergy Research & Education |url=http://www.foodallergy.org/allergens |access-date=2022-12-02 |archive-url=https://web.archive.org/web/20131209220823/http://www.foodallergy.org/allergens |archive-date=9 December 2013 }}</ref> The most common food allergens include [[Milk allergy|milk]], [[Egg allergy|eggs]], [[Peanut allergy|peanuts]], [[Tree nut allergy|tree nuts]], [[Fish allergy|fish]], [[Shellfish allergy|shellfish]], [[Soy allergy|soy]], and [[Wheat allergy|wheat]],<ref name="AAFA-2007">{{cite web |date=March 28, 2007 |title=Food Allergy Facts & Figures |url=http://www.aafa.org/display.cfm?id=9&sub=30 |url-status=dead |archive-url=https://web.archive.org/web/20061207183258/http://www.aafa.org/display.cfm?id=9&sub=30 |archive-date=7 December 2006 |access-date=15 March 2007 |publisher=Asthma and Allergy Foundation of America}}</ref> which are referred to as "the big eight", and are required by US law to be on labels of foods that contain those foods.<ref name="FAIA2">{{cite web |title=Food allergy and intolerance |url=http://www.faia.org.uk/html/food_sensitivity.php |url-status=dead |archive-url=https://web.archive.org/web/20110213060410/http://www.faia.org.uk/html/food_sensitivity.php |archive-date=13 February 2011 |access-date=2010-06-08 |work=Allergy & Intolerance |publisher=Food Additives and Ingredients Association}}</ref> In April 2021, President Biden signed the FASTER Act into law. This recognized [[Sesame allergy|sesame]] as the ninth US mandatory food label allergen.<ref name="Food Allergies">{{cite web | vauthors = ((Center for Food Safety and Applied Nutrition)) |date=22 June 2022 |title=Food Allergies |url=https://www.fda.gov/food/food-labeling-nutrition/food-allergies |archive-url=https://web.archive.org/web/20201110155745/https://www.fda.gov/food/food-labeling-nutrition/food-allergies |url-status=dead |archive-date=10 November 2020 |access-date=31 July 2022 |website=FDA |language=en}}</ref><ref>{{Cite web |title=In April of 2021, President Joe Biden signed the FASTER Act into law |url=https://www.bing.com/search?q=In+April+of+2021,+President+Joe+Biden+signed+the+FASTER+Act+into+law.+This+landmark+food+allergy+law+recognizes+sesame+as+the+ninth+top+allergen,+and+requires+it+to+be+labeled+like+the+other+8+top+allergens.+It+also+encourages+research+that+will+impr&form=ANNTH1&refig=87c7c0f335604f4ca69344996a0d61a1 |access-date=2023-01-01 |website=www.bing.com}}</ref>

Peanuts, a member of the [[legume]] family, are one of the most common food allergens that induce reactions in both children and adults.<ref name="Sampson-1996">{{cite journal | vauthors = Sampson HA, Burks AW | title = Mechanisms of food allergy | journal = Annual Review of Nutrition | volume = 16 | issue = 1 | pages = 161–177 | date = July 1996 | pmid = 8839924 | doi = 10.1146/annurev.nu.16.070196.001113 }}</ref> Affecting about 2% of the Western population, peanut allergies tend to cause more severe reactions and anaphylaxis than other food allergies.<ref name="Lieberman-2021">{{cite journal | vauthors = Lieberman JA, Gupta RS, Knibb RC, Haselkorn T, Tilles S, Mack DP, Pouessel G | title = The global burden of illness of peanut allergy: A comprehensive literature review | journal = Allergy | volume = 76 | issue = 5 | pages = 1367–1384 | date = May 2021 | pmid = 33216994 | pmc = 8247890 | doi = 10.1111/all.14666 }}</ref> Tree nuts, including [[almond]]s, [[brazil nut]]s, [[cashew]]s, [[coconut]]s, [[hazelnut]]s, [[macadamia nut]]s, [[pecan]]s, [[pistachio]]s, [[pine nut]]s, and [[walnut]]s, are also common allergens. Affected individuals may be sensitive to one particular tree nut or many different ones.<ref name="Sicherer63">{{harvnb|Sicherer|2006|p=63}}</ref> Peanuts and [[seed]]s, including [[sesame seed]]s and [[poppy seed]]s, can be processed to extract oils, but trace amounts of protein may also elicit an allergic reaction.<ref name="Sicherer63" /> Peanut and tree nut allergies are lifelong conditions for the majority of those affected, although evidence shows that ~20% of those with peanut allergies and 9% of those with tree nut allergies may outgrow them.<ref>{{cite journal | vauthors = Fleischer DM, Conover-Walker MK, Matsui EC, Wood RA | title = The natural history of tree nut allergy | journal = The Journal of Allergy and Clinical Immunology | volume = 116 | issue = 5 | pages = 1087–1093 | date = November 2005 | pmid = 16275381 | doi = 10.1016/j.jaci.2005.09.002 }}</ref>

Egg allergies affect about one in 50 children but are frequently outgrown when children reach age five.<ref>{{cite journal | vauthors = Savage JH, Matsui EC, Skripak JM, Wood RA | title = The natural history of egg allergy | journal = The Journal of Allergy and Clinical Immunology | volume = 120 | issue = 6 | pages = 1413–1417 | date = December 2007 | pmid = 18073126 | doi = 10.1016/j.jaci.2007.09.040 }}</ref> Affected individuals can be sensitive to proteins both in the egg white and egg yolk, but most children are allergic to those in the white while most adults are allergic to those in the yolk.<ref>{{cite journal | vauthors = Dona DW, Suphioglu C | title = Egg Allergy: Diagnosis and Immunotherapy | journal = International Journal of Molecular Sciences | volume = 21 | issue = 14 | pages = 5010 | date = July 2020 | pmid = 32708567 | pmc = 7404024 | doi = 10.3390/ijms21145010 | doi-access = free }}</ref>

Cow's milk is the most common food allergen in infants and young children, yet many adults are also sensitized to cow's milk.<ref>{{cite journal | vauthors = Flom JD, Sicherer SH | title = Epidemiology of Cow's Milk Allergy | journal = Nutrients | volume = 11 | issue = 5 | pages = 1051 | date = May 2019 | pmid = 31083388 | pmc = 6566637 | doi = 10.3390/nu11051051 | doi-access = free }}</ref> Many affected individuals cannot tolerate dairy products such as cheese and yogurt.<ref>{{cite journal | vauthors = Ogata M, Kido J, Nakamura K | title = Oral Immunotherapy for Children with Cow's Milk Allergy | journal = Pathogens | volume = 10 | issue = 10 | pages = 1328 | date = October 2021 | pmid = 34684278 | pmc = 8539286 | doi = 10.3390/pathogens10101328 | doi-access = free }}</ref> A small portion of children with [[milk allergy]], roughly 10%, have a reaction to [[beef]] because it contains small amounts of protein that are also present in cow's milk.<ref>{{harvnb|Sicherer|2006|p=64}}</ref>

Shellfish, which are divided into [[crustacean]]s (shrimp, crab, lobster, etc.) and [[mollusk]]s (mussel, oyster, scallop, squid, octopus, snail, etc.), are the most common food allergy in adults.<ref>{{cite journal | vauthors = Wang HT, Warren CM, Gupta RS, Davis CM | title = Prevalence and Characteristics of Shellfish Allergy in the Pediatric Population of the United States | journal = The Journal of Allergy and Clinical Immunology. In Practice | volume = 8 | issue = 4 | pages = 1359–1370.e2 | date = April 2020 | pmid = 31917365 | pmc = 7951995 | doi = 10.1016/j.jaip.2019.12.027 }}</ref> People may be allergic to other types of seafood, such as fish.<ref name="HealthCanada2">{{cite web |date=2012 |title=Seafood (Fish, Crustaceans and Shellfish) - Priority food allergens |url=http://www.hc-sc.gc.ca/fn-an/pubs/securit/2016-allergen_fish-poisson/index-eng.php |url-status=live |archive-url=https://web.archive.org/web/20161120003722/http://www.hc-sc.gc.ca/fn-an/pubs/securit/2016-allergen_fish-poisson/index-eng.php |archive-date=20 November 2016 |access-date=19 November 2016 |publisher=Health Canada, Health Products and Food Branch, Food Directorate, Bureau of Chemical Safety, Food Research Division}}</ref> Fish allergies were found to be more common in countries that have high fish consumption compared to those with lower consumption.<ref>{{cite journal | vauthors = Kalic T, Radauer C, Lopata AL, Breiteneder H, Hafner C | title = Fish Allergy Around the World-Precise Diagnosis to Facilitate Patient Management | journal = Frontiers in Allergy | volume = 2 | pages = 732178 | date = 2021 | pmid = 35387047 | pmc = 8974716 | doi = 10.3389/falgy.2021.732178 | doi-access = free }}</ref>

Other common food allergens include soy and wheat.<ref name="Iweala-2018">{{cite journal | vauthors = Iweala OI, Choudhary SK, Commins SP | title = Food Allergy | journal = Current Gastroenterology Reports | volume = 20 | issue = 5 | pages = 17 | date = April 2018 | pmid = 29623490 | pmc = 5940350 | doi = 10.1007/s11894-018-0624-y }}</ref> Those allergic to wheat may be sensitized to any protein in the wheat kernel.<ref name="Sathe-2016">{{cite journal | vauthors = Sathe SK, Liu C, Zaffran VD | title = Food Allergy | journal = Annual Review of Food Science and Technology | volume = 7 | issue = 1 | pages = 191–220 | date = 2016-02-28 | pmid = 26934173 | doi = 10.1146/annurev-food-041715-033308 }}</ref> To a lesser frequency, people may be mildly allergic to raw fruits and vegetables, a disease known as [[oral allergy syndrome]].<ref name="Iweala-2018" /> Less common allergens include [[Corn allergy|maize]], spices, synthetic and natural colors,<ref>{{cite journal | vauthors = Skypala IJ | title = Food-Induced Anaphylaxis: Role of Hidden Allergens and Cofactors | journal = Frontiers in Immunology | volume = 10 | pages = 673 | date = 2019 | pmid = 31001275 | pmc = 6457317 | doi = 10.3389/fimmu.2019.00673 | doi-access = free }}</ref> and chemical additives.<ref>{{cite journal | vauthors = Andreozzi L, Giannetti A, Cipriani F, Caffarelli C, Mastrorilli C, Ricci G | title = Hypersensitivity reactions to food and drug additives: problem or myth? | journal = Acta Bio-Medica | volume = 90 | issue = 3–S | pages = 80–90 | date = January 2019 | pmid = 30830065 | pmc = 6502174 | doi = 10.23750/abm.v90i3-S.8168 }}</ref>

[[Balsam of Peru]], which is in various foods, is in the "top five" allergens most commonly causing patch test reactions in people referred to dermatology clinics.<ref>{{cite book |author1=Gottfried Schmalz |url=https://books.google.com/books?id=mrreTHuo54wC&pg=PA352 |title=Biocompatibility of Dental Materials |author2=Dorthe Arenholt Bindslev |publisher=Springer |year=2008 |isbn=9783540777823 |access-date=March 5, 2014 |archive-url=https://web.archive.org/web/20160518233136/https://books.google.com/books?id=mrreTHuo54wC&pg=PA352 |archive-date=May 18, 2016 |url-status=live}}</ref>{{Further|Milk allergy|Egg allergy|Peanut allergy|Tree nut allergy|Fish allergy|Shellfish allergy|Soy allergy|Wheat allergy|Sesame allergy}}

=== Routes of exposure ===
Exposure to certain food proteins triggers the production of antigen-specific immunoglobulin E (IgE) antibodies, which, if unaccompanied by allergic symptoms, is known as allergic [[Sensitization (immunology)|sensitization]].<ref>{{cite journal | vauthors = Yoo Y, Perzanowski MS | title = Allergic sensitization and the environment: latest update | journal = Current Allergy and Asthma Reports | volume = 14 | issue = 10 | pages = 465 | date = October 2014 | pmid = 25149167 | pmc = 6421846 | doi = 10.1007/s11882-014-0465-1 }}</ref> Oral ingestion is the main sensitization route for most food allergy cases, yet other routes of exposure include inhalation and skin contact.<ref>{{cite journal | vauthors = Valenta R, Hochwallner H, Linhart B, Pahr S | title = Food allergies: the basics | journal = Gastroenterology | volume = 148 | issue = 6 | pages = 1120–31.e4 | date = May 2015 | pmid = 25680669 | pmc = 4414527 | doi = 10.1053/j.gastro.2015.02.006 }}</ref><ref name="Sathe-2016"/>

For example, inhaling airborne particles in a farm-scale or factory-scale peanut shelling/crushing environment, or from cooking, can induce respiratory effects in allergic individuals.<ref name="Johnson-2013">{{cite journal | vauthors = Johnson RM, Barnes CS | title = Airborne concentrations of peanut protein | journal = Allergy and Asthma Proceedings | volume = 34 | issue = 1 | pages = 59–64 | date = 2013 | pmid = 23406937 | doi = 10.2500/aap.2013.34.3622 }}</ref> Furthermore, peanut allergies are much more common in adults who had oozing and crusted skin rashes as infants,<ref name="Foong-2017">{{cite journal | vauthors = Foong RX, Brough H | title = The role of environmental exposure to peanut in the development of clinical allergy to peanut | journal = Clinical and Experimental Allergy | volume = 47 | issue = 10 | pages = 1232–1238 | date = October 2017 | pmid = 28779526 | doi = 10.1111/cea.12992 | s2cid = 10119958 }}</ref> suggesting that impaired skin may be a risk factor for sensitization.<ref name="Sathe-2016"/><ref name="Kulis-2021">{{cite journal | vauthors = Kulis MD, Smeekens JM, Immormino RM, Moran TP | title = The airway as a route of sensitization to peanut: An update to the dual allergen exposure hypothesis | language = English | journal = The Journal of Allergy and Clinical Immunology | volume = 148 | issue = 3 | pages = 689–693 | date = September 2021 | pmid = 34111450 | pmc = 8429226 | doi = 10.1016/j.jaci.2021.05.035 }}</ref> An estimated 28.5 million people worldwide are engaged in the seafood industry, which includes fishing, aquaculture, processing and industrial cooking.<ref name="Lopata-2013">{{cite journal | vauthors = Lopata AL, Jeebhay MF | title = Airborne seafood allergens as a cause of occupational allergy and asthma | journal = Current Allergy and Asthma Reports | volume = 13 | issue = 3 | pages = 288–297 | date = June 2013 | pmid = 23575656 | doi = 10.1007/s11882-013-0347-y | s2cid = 1276304 }}</ref> In these occupational settings, individuals with fish and shellfish allergies are at high risk of exposure to allergenic proteins via [[aerosolization]].<ref>{{cite journal | vauthors = Ramirez DA, Bahna SL | title = Food hypersensitivity by inhalation | journal = Clinical and Molecular Allergy | volume = 7 | issue = 1 | pages = 4 | date = February 2009 | pmid = 19232116 | pmc = 2651849 | doi = 10.1186/1476-7961-7-4 | doi-access = free }}</ref><ref name="Lopata-2013" /> Respiratory symptoms may be induced by inhalation of wet [[aerosol]]s from fresh fish handling, inhalation of dry aerosols from fishmeal processing, and dermal contact through skin breaks and cuts.<ref>{{cite journal | vauthors = Jeebhay MF, Robins TG, Lehrer SB, Lopata AL | title = Occupational seafood allergy: a review | journal = Occupational and Environmental Medicine | volume = 58 | issue = 9 | pages = 553–562 | date = September 2001 | pmid = 11511741 | pmc = 1740192 | doi = 10.1136/oem.58.9.553 }}</ref><ref name="Lopata-2013" /> Another occupational food allergy that involves respiratory symptoms is "baker's asthma," which commonly develops in food service workers who work with baked goods.<ref>{{cite journal | vauthors = Brant A | title = Baker's asthma | journal = Current Opinion in Allergy and Clinical Immunology | volume = 7 | issue = 2 | pages = 152–155 | date = April 2007 | pmid = 17351468 | doi = 10.1097/ACI.0b013e328042ba77 | s2cid = 24085274 }}</ref> Previous studies detected 40 allergens from wheat, some cross-reacted with rye proteins and a few cross-reacted with grass pollens.<ref>{{cite journal | vauthors = Saygin D, Tabib T, Bittar HE, Valenzi E, Sembrat J, Chan SY, Rojas M, Lafyatis R | display-authors = 6 | title = Transcriptional profiling of lung cell populations in idiopathic pulmonary arterial hypertension | journal = Pulmonary Circulation | volume = 10 | issue = 1 | pages = 392–406 | date = 1976 | pmid = 32166015 | doi = 10.1177/2045894020908782 | pmc = 7052475 }}</ref>

Allergic sensitization can occur via skin antigen exposure, which usually manifests as [[hives]].<ref name="Calvani-2020">{{cite journal | vauthors = Calvani M, Anania C, Caffarelli C, Martelli A, Miraglia Del Giudice M, Cravidi C, Duse M, Manti S, Tosca MA, Cardinale F, Chiappini E, Olivero F, Marseglia GL | display-authors = 6 | title = Food allergy: an updated review on pathogenesis, diagnosis, prevention and management | journal = Acta Bio-Medica | volume = 91 | issue = 11–S | pages = e2020012 | date = September 2020 | pmid = 33004782 | pmc = 8023067 | doi = 10.23750/abm.v91i11-S.10316 }}</ref> The skin has been suggested to be a critical sensitization route for peanut-allergic individuals.<ref>{{cite journal | vauthors = Thompson RL, Miles LM, Lunn J, Devereux G, Dearman RJ, Strid J, Buttriss JL | title = Peanut sensitisation and allergy: influence of early life exposure to peanuts | journal = The British Journal of Nutrition | volume = 103 | issue = 9 | pages = 1278–1286 | date = May 2010 | pmid = 20100372 | doi = 10.1017/S000711450999376X | s2cid = 3619861 | doi-access = free }}</ref><ref name="Johnson-2013" /> Peanut allergies are much more common in adults who had oozing and crusted skin rashes as infants,<ref name="Foong-2017" /> reinforcing that those with disrupted epithelial barriers, notably the skin barrier, are more prone to skin sensitization.<ref name="Sathe-2016" /> Environmental factors, such as exposure to food, microorganisms, creams, and detergents, may lead to skin barrier dysfunction.<ref name="Brough-2020">{{cite journal | vauthors = Brough HA, Nadeau KC, Sindher SB, Alkotob SS, Chan S, Bahnson HT, Leung DY, Lack G | display-authors = 6 | title = Epicutaneous sensitization in the development of food allergy: What is the evidence and how can this be prevented? | journal = Allergy | volume = 75 | issue = 9 | pages = 2185–2205 | date = September 2020 | pmid = 32249942 | pmc = 7494573 | doi = 10.1111/all.14304 }}</ref> Several studies reveal that children exposed to skin creams containing peanut oil are reported to have a higher risk of peanut allergy,<ref name="Brough-2020" /> suggesting that impaired skin may be a risk factor for sensitization.<ref name="Sathe-2016" /><ref name="Kulis-2021" />

=== Cross-contact ===
Cross-contact of food occurs when allergens are unintentionally transferred from one food item to another, often through shared cooking equipment, not properly cleaned surfaces, or utensils. This can lead to severe allergic reactions in individuals with food allergies, even if the allergen is present in trace amounts.<ref>{{Cite web |title=Dangers of Cross-Contamination |url=https://www.makefoodsafe.com/dangers-of-cross-contamination/ |access-date=2025-02-21 |website=The Lange Law Firm |language=en-US}}</ref> To mitigate risks, food labeling regulations such as in the United States, require manufacturers to clearly indicate potential allergens on packaging, often with statements like "may contain" or "processed in a facility that handles." Proper handling practices, such as thorough cleaning and separation of allergen-free foods, are essential in both commercial and home kitchens to prevent cross-contact and ensure safety for those with food allergies. Although the term cross-contamination is often used interchangeably with cross-contact, the FDA specifies that cross contamination is associated with the spread of biological, physical, and chemical contaminants in food while cross-contact is associated with food allergens.<ref>[https://web.archive.org/web/20241004173526/https://www.fda.gov/food/nutrition-food-labeling-and-critical-foods/food-allergies fda.gov]</ref>

===Atopy===
Food allergies develop more easily in people with the [[atopic syndrome]], a very common combination of diseases: [[allergic rhinitis]] and [[allergic conjunctivitis|conjunctivitis]], [[eczema]], and [[asthma]].<ref>{{cite web |url=http://www.icd9data.com/2007/Volume1/680-709/690-698/691/691.8.htm |work=ICD9 |title=Other atopic dermatitis and related conditions |url-status=live |archive-url=https://web.archive.org/web/20070930074752/http://www.icd9data.com/2007/Volume1/680-709/690-698/691/691.8.htm |archive-date=2007-09-30 }}</ref> The syndrome has a strong inherited component; a family history of allergic diseases can be indicative of the atopic syndrome.{{medical citation needed|date=November 2014}}

===Cross-reactivity===
Some children who are allergic to cow's milk protein also show a cross-sensitivity to soy-based products.<ref>{{cite web |url=http://aappolicy.aappublications.org/cgi/content/full/pediatrics;106/2/346 |title=Policy Statement: Hypoallergenic Infant Formulas |date=August 2, 2000 |publisher=American Academy of Pediatrics |url-status=dead |archive-url=https://web.archive.org/web/20080116002528/http://aappolicy.aappublications.org/cgi/content/full/pediatrics%3B106/2/346 |archive-date=16 January 2008 |access-date=26 January 2008 }}</ref> Some infant formulas have their milk and [[soy protein]]s hydrolyzed, so when taken by infants, their [[immune system]]s do not recognize the allergen and they can safely consume the product. Hypoallergenic infant formulas can be based on proteins partially predigested to a less antigenic form. Other formulas, based on free amino acids, are the least antigenic and provide complete nutritional support in severe forms of milk allergy.<ref>{{Cite journal |last1=Sicherer |first1=SH |last2=Noone |first2=SA |last3=Koerner |first3=CB |last4=Christie |first4=L |last5=Burks |first5=AW |last6=Sampson |first6=HA |date=May 2001 |title=Hypoallergenicity and efficacy of an amino acid–based formula in children with cow's milk and multiple food hypersensitivities |url=https://www.jpeds.com/article/S0022-3476(01)16072-5/fulltext |journal=The Journal of Pediatrics |volume=138 |issue=5 |pages=688–93 |doi=10.1067/mpd.2001.113007 |issn=0022-3476 |pmid=11343044|url-access=subscription }}</ref>

Crustaceans (shrimp, crab, lobster, etc.) and molluscs (mussel, oyster, scallop, squid, octopus, snail, etc.) are different [[invertebrate]] classes, but the allergenic protein [[tropomyosin]] is present and responsible for cross-reactivity.<ref>{{cite journal | vauthors = Lopata AL, Kleine-Tebbe J, Kamath SD | title = Allergens and molecular diagnostics of shellfish allergy: Part 22 of the Series Molecular Allergology | journal = Allergo Journal International | volume = 25 | issue = 7 | pages = 210–218 | date = 2016 | pmid = 28239537 | pmc = 5306157 | doi = 10.1007/s40629-016-0124-2 }}</ref>

People with latex allergy often also develop allergies to bananas, kiwifruit, avocados, and some other foods.<ref>{{cite web |url=http://www.foodallergy.org/allergens/other-allergens#latex |publisher=Food Allergy Research & Education |title=Other Common Allergens |url-status=dead |archive-url=https://web.archive.org/web/20140616031221/http://www.foodallergy.org/allergens/other-allergens#latex |archive-date=16 June 2014 |access-date=12 June 2014 }}</ref>

==Pathophysiology==
[[image:Histamin - Histamine.svg|thumb|Histamine, the structure shown, causes a person to feel itchy during an allergic reaction.]]
<!-- A food allergy occurs when the human immune system reacts abnormally to certain foods.<ref name=nhs>{{cite web |url=http://www.nhs.uk/conditions/food-allergy/Pages/Intro1.aspx |quote=A food allergy is when the body's immune system reacts unusually to specific foods |access-date=31 January 2017 |title=Food allergy |publisher=[[NHS Choices]] |date=16 May 2016 |url-status=live |archive-url=https://web.archive.org/web/20170131050131/http://www.nhs.uk/conditions/food-allergy/pages/intro1.aspx |archive-date=31 January 2017 }}</ref>
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Conditions caused by food allergies are classified into three groups according to the mechanism of the allergic response:<ref name=nhs>{{cite web |url=http://www.nhs.uk/conditions/food-allergy/Pages/Intro1.aspx |quote=A food allergy is when the body's immune system reacts unusually to specific foods |access-date=31 January 2017 |title=Food allergy |publisher=[[NHS Choices]] |date=16 May 2016}}</ref>

# IgE-mediated (classic)&nbsp;– the most common type, occurs shortly after eating and may involve [[anaphylaxis]].
# Non-IgE mediated&nbsp;– characterized by an immune response not involving [[immunoglobulin E]]; may occur some hours after eating, complicating diagnosis
# IgE and/or non-IgE-mediated&nbsp;– a hybrid of the above two types

[[Allergic reactions]] are abnormal immune responses to certain substances that are normally harmless. When immune cells encounter the allergenic protein, IgE antibodies are produced; this is similar to the immune system's reaction to foreign [[pathogen]]s. The IgE antibodies identify the allergenic proteins as harmful and initiate the allergic reaction. The harmful proteins are those that do not break down due to the strong bonds of the protein. IgE antibodies bind to a receptor on the surface of the protein, creating a tag, just as a virus or parasite becomes tagged. Why some proteins do not denature and subsequently trigger allergic reactions and hypersensitivity while others do is not entirely clear.<ref>Food Reactions. [http://www.foodreactions.org/allergy/ Allergies] {{webarchive|url=https://web.archive.org/web/20100416042849/http://www.foodreactions.org/allergy/ |date=2010-04-16 }}. Foodreactions.org.  Kent, England. 2005. Accessed 27 Apr 2010.</ref>

Hypersensitivities are categorized according to the parts of the immune system that are attacked and the amount of time it takes for the response to occur.  The four types of [[hypersensitivity reaction]] are:  type 1, immediate IgE-mediated; type 2, cytotoxic; type 3, immune complex-mediated; and type 4, delayed cell-mediated.<ref>{{harvnb|Nester|2009|p=414}}</ref> The [[pathophysiology]] of allergic responses can be divided into two phases. The first is an [[Acute (medical)|acute response]] that occurs immediately after exposure to an allergen. This phase can either subside or progress into a "late-phase reaction" which can substantially prolong the symptoms of a response, and result in tissue damage.<ref>{{Citation |last=Charles A Janeway |first=Jr |title=Effector mechanisms in allergic reactions |date=2001 |work=Immunobiology: The Immune System in Health and Disease. 5th edition |url=https://www.ncbi.nlm.nih.gov/books/NBK27112/ |access-date=2025-02-21 |publisher=Garland Science |language=en |last2=Travers |first2=Paul |last3=Walport |first3=Mark |last4=Shlomchik |first4=Mark J.}}</ref>

Many food allergies are caused by hypersensitivities to particular proteins in different foods.  Proteins have unique properties that allow them to become allergens, such as stabilizing forces in their tertiary and quaternary structures which prevent degradation during digestion. Many theoretically allergenic proteins cannot survive the destructive environment of the digestive tract, thus do not trigger hypersensitive reactions.<ref>Mayo Clinic. [http://www.mayoclinic.com/health/food-allergy/AN00179 Causes of Food Allergies.] {{webarchive|url=https://web.archive.org/web/20100227100210/http://www.mayoclinic.com/health/food-allergy/AN00179 |date=2010-02-27 }} April 2010.</ref>

===Acute response===
[[Image:Allergy degranulation processes 01.svg|thumb|Degranulation process in allergy:<br />'''1''' — antigen<br />'''2''' — IgE antibody<br />'''3''' — FcεRI receptor<br />'''4''' — preformed mediators (histamine, proteases, chemokines, heparin)<br />'''5''' — [[Granule (cell biology)|granules]]<br />'''6''' — [[mast cell]]<br />'''7''' — newly formed mediators (prostaglandins, leukotrienes, thromboxanes, PAF)]]
In the early stages of allergy, a type I hypersensitivity reaction against an allergen, encountered for the first time, causes a response in a type of immune cell called a [[T helper cell|T<sub>H</sub>2 lymphocyte]], which belongs to a subset of [[T cell]]s that produce a [[cytokine]] called [[interleukin-4]] (IL-4).  These T<sub>H</sub>2 cells interact with other [[lymphocytes]] called [[B cell]]s, whose role is the production of antibodies.  Coupled with signals provided by IL-4, this interaction stimulates the B cell to begin production of a large amount of a particular type of antibody known as IgE.  Secreted IgE circulates in the blood and binds to an IgE-specific receptor (a kind of [[Fc receptor]] called [[FcεRI]]) on the surface of other kinds of immune cells called [[mast cell]]s and [[basophil]]s, which are both involved in the acute inflammatory response.  The IgE-coated cells, at this stage, are sensitized to the allergen.<ref name=Janeway>{{cite book | vauthors = Janeway C, Travers P, Walport M, Shlomchik M | author-link = Charles Janeway | title = Immunobiology; Fifth Edition | publisher = Garland Science | year = 2001 | location = New York and London | pages = e–book | url = https://www.ncbi.nlm.nih.gov/books/bv.fcgi?call=bv.View..ShowTOC&rid=imm.TOC&depth=10 | isbn = 978-0-8153-4101-7 | url-status = live | archive-url = https://web.archive.org/web/20090628195820/http://www.ncbi.nlm.nih.gov/books/bv.fcgi?call=bv.View..ShowTOC&rid=imm.TOC&depth=10 | archive-date = 2009-06-28 }}</ref>

If later exposure to the same allergen occurs, the allergen can bind to the IgE molecules held on the surface of the mast cells or basophils.  Cross-linking of the IgE and Fc receptors occurs when more than one IgE-receptor complex interacts with the same allergenic molecule and activates the sensitized cell.  Activated mast cells and basophils undergo a process called [[degranulation]], during which they release [[histamine]] and other inflammatory chemical mediators ([[cytokine]]s, [[interleukin]]s, [[leukotriene]]s, and [[prostaglandin]]s) from their [[Granule (cell biology)|granule]]s into the surrounding tissue causing several systemic effects, such as [[vasodilation]], [[Mucous membrane|mucous]] secretion, [[nerve]] stimulation, and [[smooth muscle|smooth-muscle]] contraction. This results in [[rhinorrhea]], itchiness, [[dyspnea]], and [[anaphylaxis]]. Depending on the individual, the allergen, and the mode of introduction, the symptoms can be system-wide (classical anaphylaxis), or localized to particular body systems.<ref name=Janeway/>

===Late-phase response===
After the chemical mediators of the acute response subside, late-phase responses can often occur due to the migration of other [[leukocyte]]s such as [[neutrophil]]s, [[lymphocyte]]s, [[eosinophil]]s, and [[macrophage]]s to the initial site. The reaction is usually seen 2–24 hours after the original reaction.<ref>{{cite journal | vauthors = Grimbaldeston MA, Metz M, Yu M, Tsai M, Galli SJ | title = Effector and potential immunoregulatory roles of mast cells in IgE-associated acquired immune responses | journal = Current Opinion in Immunology | volume = 18 | issue = 6 | pages = 751–760 | date = December 2006 | pmid = 17011762 | doi = 10.1016/j.coi.2006.09.011 }}</ref> Cytokines from mast cells may also play a role in the persistence of long-term effects.<ref>{{cite journal | vauthors = Holt PG, Sly PD | title = Th2 cytokines in the asthma late-phase response | journal = Lancet | volume = 370 | issue = 9596 | pages = 1396–1398 | date = October 2007 | pmid = 17950849 | doi = 10.1016/S0140-6736(07)61587-6 | s2cid = 40819814 }}</ref>

== Diagnosis ==
[[Image:Allergy skin testing.JPG|thumb|Skin testing on the arm is a common way for detecting an allergy, but it is not as effective as other tests.]]
[[File:Epikutanni-test.jpg|thumb|[[Patch test]]]]
Diagnosis is usually based on a [[medical history]], [[elimination diet]], [[skin prick test]], blood tests for food-specific IgE [[antibodies]], or [[oral food challenge]].<ref name=NIH2012pdf/><ref name=Sic2014/>
* For [[skin prick test|skin-prick test]]s, a tiny board with protruding needles is used.  The allergens are placed either on the board or directly on the skin.  The board is then placed on the skin, to puncture the skin and for the allergens to enter the body. If a hive appears, the person is considered positive for the allergy. This test only works for IgE antibodies.  Allergic reactions caused by other antibodies cannot be detected through skin-prick tests.<ref>{{harvnb|Sicherer|2006|p=185}}</ref>

Skin-prick testing is easy to do and results are available in minutes. Different allergists may use different devices for testing. Some use a "[[bifurcated needle]]", which looks like a fork with two prongs. Others use a "multitest", which may look like a small board with several pins sticking out of it. In these tests, a tiny amount of the suspected allergen is put onto the skin or into a testing device, and the device is placed on the skin to prick, or break through, the top layer of skin. This puts a small amount of the allergen under the skin. A hive will form at any spot where the person is allergic. This test generally yields a positive or negative result. It is good for quickly learning if a person is allergic to a particular food or not because it detects IgE. Skin tests cannot predict if a reaction would occur or what kind of reaction might occur if a person ingests that particular allergen. They can, however, confirm an allergy in light of a patient's history of reactions to a particular food. Non-IgE-mediated allergies cannot be detected by this method.
* [[Patch test]]ing is used to determine if a specific substance causes allergic inflammation of the skin. It tests for delayed food reactions.<ref>{{cite web |url=http://apfed.org/drupal/drupal/allergies_and_EoE |title=Allergies and EGIDs &#124; American Partnership For Eosinophilic Disorders |publisher=Apfed.org |access-date=2014-03-31 |archive-url=https://web.archive.org/web/20150504132527/http://apfed.org/drupal/drupal/allergies_and_EoE |archive-date=4 May 2015 |url-status=dead }}</ref><ref>{{cite web |url=https://www.elsevier.pt/en/revistas/allergologia-et-immunopathologia-105/artigo/patch-test-in-the-diagnosis-of-food-allergy-13142485 |title=Patch test in the diagnosis of food allergy |date=2014-03-22 |access-date=2014-03-31 |url-status=dead |archive-url=https://web.archive.org/web/20140310034619/http://www.elsevier.pt/en/revistas/allergologia-et-immunopathologia-105/artigo/patch-test-in-the-diagnosis-of-food-allergy-13142485 |archive-date=2014-03-10 }}</ref><ref>{{cite journal | vauthors = Rokaite R, Labanauskas L, Vaideliene L | title = Role of the skin patch test in diagnosing food allergy in children with atopic dermatitis | journal = Medicina | volume = 40 | issue = 11 | pages = 1081–1087 | date = 2014-01-24 | pmid = 15547309 }}</ref>
* [[Blood test]]ing is another way to test for allergies; however, it poses the same disadvantage and only detects IgE allergens and does not work for every possible allergen.  [[RAST test|Radioallergosorbent testing]] (RAST) is used to detect IgE antibodies present to a certain allergen. The score taken from the RAST is compared to predictive values, taken from a specific type of RAST. If the score is higher than the predictive values, a great chance the allergy is present in the person exists. One advantage of this test is that it can test many allergens at one time.<ref>{{harvnb|Sicherer|2006|pp=187–8}}</ref>

A CAP-RAST has greater specificity than RAST; it can show the amount of IgE present to each allergen.<ref>
{{cite web | title=What is a RAST test ? What is a CAP-RAST test? | url=http://www.kidswithfoodallergies.org/resourcespre.php?id=48&title=What%20is%20a%20RAST%20test%20?%20%20What%20is%20a%20CAP-RAST%20test | publisher=kidswithfoodallergies.org | url-status=live | archive-url=https://web.archive.org/web/20130511081643/http://www.kidswithfoodallergies.org/resourcespre.php?id=48&title=What%20is%20a%20RAST%20test%20%3F%20%20What%20is%20a%20CAP-RAST%20test%3F | archive-date=2013-05-11 }}</ref> Researchers have been able to determine "predictive values" for certain foods, which can be compared to the RAST results. If a person's RAST score is higher than the predictive value for that food, over a 95% chance exists that patients will have an allergic reaction (limited to rash and anaphylaxis reactions) if they ingest that food. {{Citation needed|date=February 2007}} Currently,{{when|date=September 2019}} predictive values are available for milk, egg, peanut, fish, soy, and wheat.<ref>
{{cite journal | vauthors = Sampson HA, Ho DG | title = Relationship between food-specific IgE concentrations and the risk of positive food challenges in children and adolescents | journal = The Journal of Allergy and Clinical Immunology | volume = 100 | issue = 4 | pages = 444–451 | date = October 1997 | pmid = 9338535 | doi = 10.1016/S0091-6749(97)70133-7 | doi-access = free }}</ref><ref>
{{cite journal | vauthors = Sampson HA | title = Utility of food-specific IgE concentrations in predicting symptomatic food allergy | journal = The Journal of Allergy and Clinical Immunology | volume = 107 | issue = 5 | pages = 891–896 | date = May 2001 | pmid = 11344358 | doi = 10.1067/mai.2001.114708 }}</ref><ref>{{cite journal | vauthors = García-Ara C, Boyano-Martínez T, Díaz-Pena JM, Martín-Muñoz F, Reche-Frutos M, Martín-Esteban M | title = Specific IgE levels in the diagnosis of immediate hypersensitivity to cows' milk protein in the infant | journal = The Journal of Allergy and Clinical Immunology | volume = 107 | issue = 1 | pages = 185–190 | date = January 2001 | pmid = 11150010 | doi = 10.1067/mai.2001.111592 | doi-access = free }}</ref> Blood tests allow for hundreds of allergens to be screened from a single sample, and cover food allergies as well as inhalants. However, non-IgE-mediated allergies cannot be detected by this method. Other widely promoted tests such as the [[antigen leukocyte cellular antibody test]] and the food allergy profile are considered unproven methods, the use of which is not advised.<ref>{{cite journal | vauthors = Wüthrich B | title = Unproven techniques in allergy diagnosis | journal = Journal of Investigational Allergology & Clinical Immunology | volume = 15 | issue = 2 | pages = 86–90 | year = 2005 | pmid = 16047707 }}</ref>
* [[Elimination diet|Food challenges]] test for allergens other than those caused by IgE allergens. The allergen is given to the person in the form of a pill, so the person can ingest the allergen directly.  The person is watched for signs and symptoms. The problem with food challenges is that they must be performed in the hospital under careful watch, due to the possibility of [[anaphylaxis]].<ref>{{harvnb|Sicherer|2006|p=189}}</ref>

Food challenges, especially [[double-blind]], placebo-controlled food challenges, are the gold standard for diagnosis of food allergies, including most non-IgE-mediated reactions, but is rarely done.<ref name="TurnbullAdams2015">{{cite journal | vauthors = Turnbull JL, Adams HN, Gorard DA | title = Review article: the diagnosis and management of food allergy and food intolerances | journal = Alimentary Pharmacology & Therapeutics | volume = 41 | issue = 1 | pages = 3–25 | date = January 2015 | pmid = 25316115 | doi = 10.1111/apt.12984 | type = Review | s2cid = 31761992 | doi-access = free }}{{open access}}</ref> Blind food challenges involve packaging the suspected allergen into a capsule, giving it to the patient, and observing the patient for signs or symptoms of an allergic reaction.{{medical citation needed|date=September 2019}}

The recommended method for diagnosing food allergy is to be assessed by an allergist. The allergist will review the patient's history and the symptoms or reactions that have been noted after food ingestion. If the allergist feels the symptoms or reactions are consistent with food allergy, he/she will perform allergy tests. Additional diagnostic tools for evaluation of eosinophilic or non-IgE mediated reactions include [[endoscopy]], [[colonoscopy]], and [[biopsy]].{{medical citation needed|date=September 2019}}

===Differential diagnosis===
Important [[Differential diagnosis|differential diagnoses]] are:
* [[Lactose intolerance]] generally develops later in life, but can present in young patients in severe cases. It is not an immune reaction and is due to an enzyme deficiency ([[lactase]]). It is more common in many non-Western people.
* [[Celiac disease]]. While it is caused by a permanent intolerance to [[gluten]] (present in [[wheat]], rye, barley and oats), is not an allergy nor simply an intolerance, but a chronic, [[systemic disease|multiple-organ]] [[autoimmune disorder]] primarily affecting the [[small intestine]].<ref name=NIH2015>{{cite web|title=Celiac Disease|url=http://www.niddk.nih.gov/health-information/health-topics/digestive-diseases/celiac-disease/Pages/facts.aspx|website=NIDDKD|access-date=17 March 2016|date=June 2015|url-status=live|archive-url=https://web.archive.org/web/20160313222154/http://www.niddk.nih.gov/health-information/health-topics/digestive-diseases/celiac-disease/Pages/facts.aspx|archive-date=13 March 2016|df=dmy-all}}</ref><ref name=WGO2016>{{cite web|url=http://www.worldgastroenterology.org/guidelines/global-guidelines/celiac-disease/celiac-disease-english|title=Celiac disease|date=July 2016|publisher=[[World Gastroenterology Organisation]] Global Guidelines|access-date=23 April 2017|url-status=live|archive-url=https://web.archive.org/web/20170317123604/http://www.worldgastroenterology.org/guidelines/global-guidelines/celiac-disease/celiac-disease-english|archive-date=17 March 2017|df=dmy-all}}</ref><ref name="TommasiniNot2011">{{cite journal | vauthors = Tommasini A, Not T, Ventura A | title = Ages of celiac disease: from changing environment to improved diagnostics | journal = World Journal of Gastroenterology | volume = 17 | issue = 32 | pages = 3665–3671 | date = August 2011 | pmid = 21990947 | pmc = 3181451 | doi = 10.3748/wjg.v17.i32.3665 | type = Review | doi-access = free }}</ref>
* [[Irritable bowel syndrome]]
* C1 Esterase inhibitor deficiency ([[hereditary angioedema]]), a [[rare disease]], generally causes attacks of angioedema, but can present solely with [[abdominal pain]] and occasional diarrhea, and thus may be confused with allergy-triggered angioedema.

== Prevention ==
Breastfeeding for more than four months may prevent atopic dermatitis, cow's milk allergy, and wheezing in early childhood.<ref name=Gre2008>{{cite journal | vauthors = Greer FR, Sicherer SH, Burks AW | title = Effects of early nutritional interventions on the development of atopic disease in infants and children: the role of maternal dietary restriction, breastfeeding, timing of introduction of complementary foods, and hydrolyzed formulas | journal = Pediatrics | volume = 121 | issue = 1 | pages = 183–191 | date = January 2008 | pmid = 18166574 | doi = 10.1542/peds.2007-3022 | doi-access = free }}</ref> Early exposure to potential allergens may be protective.<ref name=Sic2014/> Specifically, early exposure to eggs and peanuts reduces the risk of allergies to these.<ref name=Ie2016/> Guidelines suggest introducing peanuts as early as 4–6 months and include precautionary measures for high-risk infants.<ref>{{cite journal | vauthors = Chan ES, Abrams EM, Hildebrand KJ, Watson W | title = Early introduction of foods to prevent food allergy | journal = Allergy, Asthma, and Clinical Immunology | volume = 14 | issue = Suppl 2 | pages = 57 | date = 2018-09-12 | pmid = 30275847 | pmc = 6157280 | doi = 10.1186/s13223-018-0286-1 | doi-access = free }}</ref> The former guidelines, advising delaying the introduction of peanuts, are now{{when|date=September 2019}} thought to have contributed to the increase in peanut allergy seen recently.<ref>{{cite journal | vauthors = Du Toit G, Roberts G, Sayre PH, Bahnson HT, Radulovic S, Santos AF, Brough HA, Phippard D, Basting M, Feeney M, Turcanu V, Sever ML, Gomez Lorenzo M, Plaut M, Lack G | display-authors = 6 | title = Randomized trial of peanut consumption in infants at risk for peanut allergy | journal = The New England Journal of Medicine | volume = 372 | issue = 9 | pages = 803–813 | date = February 2015 | pmid = 25705822 | pmc = 4416404 | doi = 10.1056/NEJMoa1414850 }}</ref>{{Better source needed|date=August 2019}}

To avoid an allergic reaction, a strict diet can be followed. It is difficult to determine the amount of allergenic food required to elicit a reaction, so complete avoidance should be attempted.  In some cases, hypersensitive reactions can be triggered by exposures to allergens through skin contact, inhalation, kissing, participation in sports, [[blood transfusion]]s, cosmetics, and alcohol.<ref>{{harvnb|Sicherer|2006|pp=151–8}}</ref>

Early introduction of peanut and egg alongside other solids, or by one year of age, may help prevent development of food allergy. Introduction of these allergenic foods within the first year of life appears to be safe. A window of opportunity for the introduction of different food allergens may exist, such as egg introduction ahead of peanut.<ref>{{Cite web |title=Introducing Foods and Allergy Prevention |url=https://www.allergy.org.au/patients/fast-facts/introducing-foods-and-allergy-prevention#:~:text=Studies%20show%20that%20introducing%20common%20allergy%20causing%20foods,nuts,%20soy,%20sesame,%20wheat,%20fish%20and%20other%20seafood. |access-date=2023-01-01 |website=- Australasian Society of Clinical Immunology and Allergy (ASCIA)}}</ref>

===Inhalation exposure===
Allergic reactions to airborne particles or vapors of known food allergens have been reported as an occupational consequence of people working in the food industry, but can also take place in home situations, restaurants, or confined spaces such as airplanes. According to two reviews, respiratory symptoms are common, but in some cases there has been progression to anaphylaxis.<ref name=Leonardi2014>{{cite journal | vauthors = Leonardi S, Pecoraro R, Filippelli M, Miraglia del Giudice M, Marseglia G, Salpietro C, Arrigo T, Stringari G, Ricò S, La Rosa M, Caffarelli C | display-authors = 6 | title = Allergic reactions to foods by inhalation in children | journal = Allergy and Asthma Proceedings | volume = 35 | issue = 4 | pages = 288–294 | year = 2014 | pmid = 24992548 | doi = 10.2500/aap.2014.35.3755 }}</ref><ref>{{cite journal | vauthors = James JM, Crespo JF | title = Allergic reactions to foods by inhalation | journal = Current Allergy and Asthma Reports | volume = 7 | issue = 3 | pages = 167–174 | date = June 2007 | pmid = 17448326 | doi = 10.1007/s11882-007-0017-z | s2cid = 11974562 }}</ref> The most frequent reported cases of reactions by inhalation of allergenic foods were due to peanut, seafood, legumes, tree nut, and cow's milk.<ref name=Leonardi2014 /> Steam rising from cooking of lentils, green beans, chickpeas and fish has been well documented as triggering reactions, including anaphylactic reactions.<ref name=Leonardi2014 /><ref>{{cite journal | vauthors = Vitaliti G, Pavone P, Spataro G, Giunta L, Guglielmo F, Falsaperla R | title = Legumes steam allergy in childhood: Update of the reported cases | journal = Allergologia et Immunopathologia | volume = 43 | issue = 2 | pages = 196–202 | year = 2015 | pmid = 24411097 | doi = 10.1016/j.aller.2013.09.009 }}</ref> One review mentioned case study examples of allergic responses to inhalation of other foods, including examples in which oral consumption of the food is tolerated.<ref name=Leonardi2014 />

== Treatment ==

The mainstay of treatment for food allergy is total avoidance of the foods identified as allergens.  An allergen can enter the body by consuming a portion of food containing the allergen, and can also be ingested by touching any surfaces that may have come into contact with the allergen, then touching the eyes or nose. For people who are extremely sensitive, avoidance includes avoiding touching or inhaling problematic food. Total avoidance is complicated because the declaration of the presence of trace amounts of allergens in foods is not mandatory (see [[#Regulation of labelling|regulation of labelling]]).

If the food is accidentally ingested and a systemic reaction ([[anaphylaxis]]) occurs, then [[epinephrine]] should be used. A second dose of epinephrine may be required for severe reactions.  The person should then be transported to the [[emergency room]], where additional treatment can be given.  Other treatments include [[antihistamine]]s and [[steroid]]s.<ref>{{cite web|title=European Food Allergy and Anaphalaxis Public Declaration|url=http://infoallergy.com/Tools-Extras/foodallergycampaign/EuropeanFoodAllergyAnaphylaxisPublicDeclaration/|publisher=the European Academy of Allergy and Clinical Immunology (EAACI)|access-date=10 December 2013|url-status=dead|archive-url=https://web.archive.org/web/20131215033212/http://infoallergy.com/Tools-Extras/foodallergycampaign/EuropeanFoodAllergyAnaphylaxisPublicDeclaration/|archive-date=15 December 2013}}</ref>

===Epinephrine===
[[File:epipen.jpg|thumb|Epinephrine autoinjectors are portable single-dose epinephrine-dispensing devices used to treat anaphylaxis.]]
[[Epinephrine (medication)|Epinephrine]] (adrenaline) is the first-line treatment for severe allergic reactions (anaphylaxis). If administered in a timely manner, epinephrine can reverse its effects. Epinephrine relieves airway swelling and obstruction, and improves blood circulation; blood vessels are tightened and heart rate is increased, improving circulation to body organs.  Epinephrine is available by prescription in an [[auto-injector|autoinjector]].<ref>{{harvnb|Sicherer|2006|p=133}}</ref>

===Antihistamines===
Antihistamines can alleviate some of the milder symptoms of an allergic reaction, but do not treat all symptoms of anaphylaxis.<ref>{{harvnb|Sicherer|2006|p=131}}</ref>  Antihistamines block the action of [[histamine]], which causes blood vessels to dilate and become leaky to plasma proteins. Histamine also causes itchiness by acting on sensory nerve terminals.  The most common antihistamine given for food allergies is [[diphenhydramine]].

===Steroids===
[[Glucocorticoid|Glucocorticoid steroids]] are used to calm down the immune system cells that are attacked by the chemicals released during an allergic reaction.  This treatment in the form of a [[nasal spray]] should not be used to treat anaphylaxis, for it only relieves symptoms in the area in which the steroid is in contact.  Another reason steroids should not be used is the delay in reducing inflammation.  Steroids can also be taken orally or through injection, by which every part of the body can be reached and treated, but a long time is usually needed for these to take effect.<ref>{{harvnb|Sicherer|2006|p=134}}</ref>

=== Immunotherapy ===
[[Immunotherapies]] seek to condition the immune system to elicit or suppress a specific immune response. In the treatment of allergies, common immunotherapies seek to desensitize the immune system by gradually exposing the body to allergens in increasing amounts. These forms of immunotherapy have had varying and limited success and have generally been used to treat peanut and environmental allergies.<ref>{{Citation |last1=Persaud |first1=Y|last2=Memon |first2=RJ |last3=Savliwala |first3=MN |title=Allergy Immunotherapy |date=2023 |url=http://www.ncbi.nlm.nih.gov/books/NBK535367/ |work=StatPearls |access-date=2023-12-22 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=30570988}}</ref>

===Omalizumab===
[[Omalizumab]], an injectable asthma treatment drug sold under the brand name Xolair, was approved in the United States in February 2024 to reduce severe reactions to accidental exposure to food allergens.<ref>{{cite news |url=https://www.npr.org/2024/02/26/1233856105/asthma-drug-can-help-reduce-allergic-reactions-for-those-with-severe-food-allerg |title=Asthma drug can help reduce allergic reactions for those with severe food allergies |date=February 26, 2024 |publisher=[[NPR]] |author=Allison Aubrey}}</ref> It is a genetically engineered [[monoclonal antibody]] which specifically binds to [[immunoglobulin E]] (IgE) to reduce the severity of an immune response. Successful results were reported for wheat, eggs, milk and baked products containing wheat and milk.<ref>{{cite journal |vauthors=Zuberbier T, Wood RA, Bindslev-Jensen C, Fiocchi A, Chinthrajah RS, Worm M, Deschildre A, Fernandez-Rivas M, Santos AF, Jaumont X, Tassinari P |title=Omalizumab in IgE-Mediated Food Allergy: A Systematic Review and Meta-Analysis |journal=J Allergy Clin Immunol Pract |volume=11 |issue=4 |pages=1134–46 |date=April 2023 |pmid=36529441 |doi=10.1016/j.jaip.2022.11.036 |url=|doi-access=free }}</ref>

==Epidemiology==
Food allergies affect up to 10% of the worldwide population, and they are currently more prevalent in children (~8%) than adults (~5) in western nations.<ref name="Sathe-2016"/> In several industrialized countries, food allergies affect up to 10% of children.<ref name="Loh-2018">{{cite journal | vauthors = Loh W, Tang ML | title = The Epidemiology of Food Allergy in the Global Context | journal = International Journal of Environmental Research and Public Health | volume = 15 | issue = 9 | pages = 2043 | date = September 2018 | pmid = 30231558 | pmc = 6163515 | doi = 10.3390/ijerph15092043 | doi-access = free }}</ref> Children are most commonly allergic to cow's milk, chicken eggs, peanuts, and tree nuts.<ref name="Sampson-1996"/> While studies on adults with food allergy are not as abundant, surveys suggest that the most common food allergens for adults include fish, shellfish, peanuts, and tree nuts.<ref name="Loh-2018" />

Food allergies have become increasingly prevalent in industrialized/westernized nations over the last 2–3 decades.<ref>{{cite book | vauthors = Lopez CM, Yarrarapu SN, Mendez MD |title=Food Allergies |date=2022 |url=http://www.ncbi.nlm.nih.gov/books/NBK482187/ |work=StatPearls |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=29489188  }}</ref> An estimated 15 million people currently have food allergies in the United States.<ref name="Iweala-2019">{{cite journal | vauthors = Iweala OI, Nagler CR | title = The Microbiome and Food Allergy | journal = Annual Review of Immunology | volume = 37 | issue = 1 | pages = 377–403 | date = April 2019 | pmid = 31026410 | doi = 10.1146/annurev-immunol-042718-041621 | pmc = 10445337 | s2cid = 135423279 }}</ref> In 1997, 0.4% children in the United States were reported to have peanut allergy, yet this number markedly rose to 1.4% in 2008.<ref>{{cite journal | vauthors = Warren CM, Jiang J, Gupta RS | title = Epidemiology and Burden of Food Allergy | journal = Current Allergy and Asthma Reports | volume = 20 | issue = 2 | pages = 6 | date = February 2020 | pmid = 32067114 | pmc = 7883751 | doi = 10.1007/s11882-020-0898-7 }}</ref> In Australia, hospital admission rates for food-induced anaphylaxis increased by an average of 13.2% from 1994–2005.<ref name="Loh-2018" /> One possible explanation for the rise in food allergy is the "old friends" hypothesis, which suggests that non-disease-causing organisms, such as [[helminth]]s, could protect against allergy. Therefore, reduced exposure to these organisms, particularly in developed countries, could have contributed towards the increase.{{Citation needed|date=February 2023}}

Children of East Asian or African descent who live in westernized countries were reported to be at significantly higher risk of food allergy compared to Caucasian children.<ref name="Sicherer-2018"/> Several studies predict that Asia and Africa may experience a growth in food allergy prevalence as the lifestyles there become more westernized.<ref name="Loh-2018" />

The prevalence of certain food allergies is suggested to depend partly on the geographical area and country. For instance, allergy to [[buckwheat]] flour, used for [[soba]] noodles, is more common in Japan than peanuts, tree nuts or foods made from soy beans.<ref>{{cite journal | vauthors = Urisu A, Ebisawa M, Ito K, Aihara Y, Ito S, Mayumi M, Kohno Y, Kondo N | display-authors = 6 | title = Japanese Guideline for Food Allergy 2014 | journal = Allergology International | volume = 63 | issue = 3 | pages = 399–419 | date = September 2014 | pmid = 25178179 | doi = 10.2332/allergolint.14-RAI-0770 | collaboration = Japanese Society of Allergology, Japanese Society of Pediatric Allergy and Clinical Immunology, Committee for Japanese Pediatric Guideline for Food Allergy | doi-access = free }}</ref> Also, shellfish allergy is the most common cause of anaphylaxis in adults and adolescents particularly in East Asian countries like Hong Kong, Taiwan, Singapore, and Thailand.<ref name="Loh-2018" /> Individuals in [[East Asia]] have further developed an allergy to [[rice]], which forms a large part of their diet.<ref>{{cite web |year=2006 |title=Rice Allergy |url=http://allergy.healthcentersonline.com/foodallergyintolerance/riceallergy2.cfm |url-status=dead |archive-url=https://web.archive.org/web/20060523180835/http://allergy.healthcentersonline.com/foodallergyintolerance/riceallergy2.cfm |archive-date=23 May 2006 |access-date=2006-10-26 |publisher=HealthCentersOnline |page=2}}</ref> Another example is that, out of nine European countries, egg allergy was found{{By whom|date=February 2023}} to be most prevalent in the UK and least prevalent in Greece.{{Citation needed|date=February 2023}}

=== Special population: children ===
About 75% of children who have allergies to milk protein are able to tolerate baked-in milk products, i.e., muffins, cookies, cake, and hydrolyzed formulas.<ref>Lucendo AJ, Arias A, Gonzalez-Cervera J, Mota-Huertas T, Yague-Compadre JL. Tolerance of a cow's milk-based hydrolyzed formula in patients with eosinophilic esophagitis triggered by milk. ''Allergy''; 68:1065–72. [https://www.ncbi.nlm.nih.gov/pubmed/23906026?dopt=Citation Link] {{webarchive|url=https://web.archive.org/web/20161128195256/https://www.ncbi.nlm.nih.gov/pubmed/23906026?dopt=Citation |date=2016-11-28 }}</ref> About 50% of children with allergies to milk, egg, soy, peanuts, tree nuts, and wheat will outgrow their allergy by the age of 6. Those who are still allergic by the age of 12 or so have less than an 8% chance of outgrowing the allergy.<ref>{{cite web |url=http://www.aafa.org/display.cfm?id=9&sub=15&cont=78 |title=What Are Food Allergies? Food Allergy Summary |date=March 28, 2007 |publisher=Asthma and Allergy Foundation of America |url-status=dead |archive-url=https://web.archive.org/web/20071027124950/http://www.aafa.org/display.cfm?id=9&sub=15&cont=78 |archive-date=27 October 2007 |access-date=6 April 2007 }}</ref>

===United States===
In the United States, food allergy affects as many as 5% of infants less than three years of age<ref name="Sampson">{{cite journal | vauthors = Sampson HA | title = Update on food allergy | journal = The Journal of Allergy and Clinical Immunology | volume = 113 | issue = 5 | pages = 805–19; quiz 820 | date = May 2004 | pmid = 15131561 | doi = 10.1016/j.jaci.2004.03.014 | doi-access = free }}</ref> and 3% to 4% of adults.<ref name="SichererS470">{{cite journal | vauthors = Sicherer SH, Sampson HA | title = 9. Food allergy | journal = The Journal of Allergy and Clinical Immunology | volume = 117 | issue = 2 Suppl Mini-Primer | pages = S470–S475 | date = February 2006 | pmid = 16455349 | doi = 10.1016/j.jaci.2005.05.048 | doi-access = free }}</ref><ref>{{cite web |url=http://www.foodallergy.org/files/MediaQA.pdf |title=Food Allergy Media Q&A |date=2010-05-26 |access-date=2011-03-25 |publisher=[[Food Allergy & Anaphylaxis Network]] |url-status=dead |archive-url=https://web.archive.org/web/20101230072147/https://www.foodallergy.org/files/MediaQA.pdf |archive-date=30 December 2010 }}</ref> The prevalence of food allergies is rising.<ref name="Kagan">
{{cite journal | vauthors = Kagan RS | title = Food allergy: an overview | journal = Environmental Health Perspectives | volume = 111 | issue = 2 | pages = 223–225 | date = February 2003 | pmid = 12573910 | pmc = 1241355 | doi = 10.1289/ehp.5702 }}</ref><ref>{{cite journal | vauthors = Branum AM, Lukacs SL | title = Food allergy among U.S. children: trends in prevalence and hospitalizations | journal = NCHS Data Brief | issue = 10 | pages = 1–8 | date = October 2008 | pmid = 19389315 }}</ref><ref>{{cite journal | vauthors = Ben-Shoshan M, Turnbull E, Clarke A | title = Food allergy: temporal trends and determinants | journal = Current Allergy and Asthma Reports | volume = 12 | issue = 4 | pages = 346–372 | date = August 2012 | pmid = 22723032 | doi = 10.1007/s11882-012-0274-3 | s2cid = 25143356 | doi-access = free }}</ref> Food allergies cause roughly 30,000 emergency room visits and 150 deaths per year.<ref>[https://web.archive.org/web/20130318054344/http://www.fda.gov/Food/GuidanceRegulation/GuidanceDocumentsRegulatoryInformation/Allergens/ucm106890.htm#q6 Question 6: How serious are food allergies?] Food Allergen Labeling And Consumer Protection Act of 2004 Questions and Answers, U.S. Food and Drug Administration (2006).</ref>
<!-- conflict For example, an estimated 8% of children have at least one food allergy, a projected total of 5.9 million children across the population, according to a 2011 study published in the journal ''Pediatrics'', "The Prevalence, Severity, and Distribution of Childhood Food Allergy in the United States."<ref>{{cite web|url = http://journalistsresource.org/studies/society/health/childhood-food-allerg/ |title = Prevalence and Severity of Child Food Allergies in the U.S. |publisher = Journalist's Resource.org }}</ref>
 -->

==Regulation==
Whether rates of food allergy are increasing or not, food allergy awareness has definitely increased, with impacts on the quality of life for children, their parents and their caregivers.<ref name=Ravid2015>{{cite journal | vauthors = Ravid NL, Annunziato RA, Ambrose MA, Chuang K, Mullarkey C, Sicherer SH, Shemesh E, Cox AL | display-authors = 6 | title = Mental health and quality-of-life concerns related to the burden of food allergy | journal = The Psychiatric Clinics of North America | volume = 38 | issue = 1 | pages = 77–89 | date = March 2015 | pmid = 25725570 | doi = 10.1016/j.psc.2014.11.004 }}</ref><ref name=Morou2014>{{cite journal | vauthors = Morou Z, Tatsioni A, Dimoliatis ID, Papadopoulos NG | title = Health-related quality of life in children with food allergy and their parents: a systematic review of the literature | journal = Journal of Investigational Allergology & Clinical Immunology | volume = 24 | issue = 6 | pages = 382–395 | year = 2014 | pmid = 25668890 }}</ref><ref name=Lange2014>{{cite journal | vauthors = Lange L | title = Quality of life in the setting of anaphylaxis and food allergy | journal = Allergo Journal International | volume = 23 | issue = 7 | pages = 252–260 | year = 2014 | pmid = 26120535 | pmc = 4479473 | doi = 10.1007/s40629-014-0029-x }}</ref><ref name=Velde2013>{{cite journal | vauthors = van der Velde JL, Dubois AE, Flokstra-de Blok BM | title = Food allergy and quality of life: what have we learned? | journal = Current Allergy and Asthma Reports | volume = 13 | issue = 6 | pages = 651–661 | date = December 2013 | pmid = 24122150 | doi = 10.1007/s11882-013-0391-7 | s2cid = 326837 }}</ref> In the United States, the Food Allergen Labeling and Consumer Protection Act of 2004 causes people to be reminded of allergy problems every time they handle a food package, and restaurants have added allergen warnings to menus. The Culinary Institute of America, a premier school for chef training, has courses in allergen-free cooking and a separate teaching kitchen.<ref>[https://www.ciachef.edu/cia-allergen-free-dining-oasis-release/ Culinary Institute of America] Allergen-free dining oasis comes to the CIA (2017)</ref> School systems have protocols about what foods can be brought into the school. Despite all these precautions, people with serious allergies are aware that accidental exposure can easily occur at other peoples' houses, at school or in restaurants.<ref name=Shah2008>{{cite journal | vauthors = Shah E, Pongracic J | title = Food-induced anaphylaxis: who, what, why, and where? | journal = Pediatric Annals | volume = 37 | issue = 8 | pages = 536–541 | date = August 2008 | pmid = 18751571 | doi = 10.3928/00904481-20080801-06 }}</ref>

===Regulation of labelling===
[[File:US Allergen Information Example.jpg|thumb|upright=1.3|An example of a list of allergens in a food item]]
In response to the risk that certain foods pose to those with food allergies, some countries have responded by instituting labeling laws that require food products to clearly inform consumers if their products contain priority allergens or byproducts of major allergens among the ingredients intentionally added to foods.

The priority allergens vary by country.
{| class="wikitable"
|+
Food allergens prioritized in labeling laws by country
!Food
!US<ref name="USFDA-2018">{{Cite web|url=https://www.fda.gov/regulatory-information/search-fda-guidance-documents/guidance-industry-questions-and-answers-regarding-food-allergens-edition-4|archive-url=https://web.archive.org/web/20190620093315/https://www.fda.gov/regulatory-information/search-fda-guidance-documents/guidance-industry-questions-and-answers-regarding-food-allergens-edition-4|url-status=dead|archive-date=20 June 2019|title=Guidance for Industry: Questions and Answers Regarding Food Allergens (Edition 4)| vauthors = ((Center for Food Safety and Applied Nutrition)) |date=2018-11-08|website=U.S. Food and Drug Administration|access-date=2019-09-08}}</ref>
!Canada<ref name="Health Canada-2005">{{Cite web|url=https://www.canada.ca/en/health-canada/services/food-nutrition/food-safety/food-allergies-intolerances/food-allergies.html|title=Common food allergens|date=2005-06-21|website=Health Canada|access-date=2019-09-08}}</ref>
!UK<ref name="FSA-2019">{{Cite web|url=https://www.food.gov.uk/business-guidance/allergen-labelling-for-food-manufacturers|title=Allergen labelling for food manufacturers|website=Food Standards Agency|access-date=2019-09-08}}</ref>
!Australia & New Zealand<ref name="Foodstandards-2024">{{Cite web |title=Allergen labelling for consumers {{!}} Food Standards Australia New Zealand |url=https://www.foodstandards.gov.au/consumer/labelling/allergen-labelling |access-date=2024-05-05 |website=www.foodstandards.gov.au}}</ref>
!EU<ref name="eu">{{cite web |url=https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:02011R1169-20180101 |title=REGULATION (EU) No 1169/2011 OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 25 October 2011 on the provision of food information to consumers, amending Regulations (EC) No 1924/2006 and (EC) No 1925/2006 of the European Parliament and of the Council, and repealing Commission Directive 87/250/EEC, Council Directive 90/496/EEC, Commission Directive 1999/10/EC, Directive 2000/13/EC of the European Parliament and of the Council, Commission Directives 2002/67/EC and 2008/5/EC and Commission Regulation (EC) No 608/2004 |date=25 October 2011 }}</ref>
|-
|peanuts
|{{Yes}}
|{{Yes}}
|{{Yes}}
|{{Yes}}
|{{Yes}}
|-
|tree nuts
|{{Yes}}
|{{Yes}}
|{{Yes}}
|{{Partial|Almonds, Brazil nuts, cashews, hazelnuts, macadamias, pecans, pistachios, pine nuts, and walnuts}}
|{{Yes}}
|-
|milk
|{{Yes}}
|{{Yes}}
|{{Yes}}
|{{Yes}}
|{{Yes}}
|-
|eggs
|{{Yes}}
|{{Yes}}
|{{Yes}}
|{{Yes}}
|{{Yes}}
|-
|fish
|{{Yes}}
|{{Yes}}
|{{Yes}}
|{{Yes}}
|{{Yes}}
|-
|shellfish
|{{Partial|Crustaceans only}}
|{{Yes|Crustaceans and molluscs}}
|{{Yes|Crustaceans and molluscs}}
|{{Yes|Crustaceans and molluscs}}
|{{Yes|Crustaceans and molluscs}}
|-
|soy
|{{Yes}}
|{{Yes}}
|{{Yes}}
|{{Yes}}
|{{Yes}}
|-
|[[gluten allergy|gluten]]
|{{No}}
|{{Yes}}
|{{Yes}}
|{{Yes}}
|{{Yes}}
|-
|wheat
|{{Yes}}
|{{Yes|Includes triticale}}
|{{Yes2|Included under gluten}}
|{{Yes}}
|{{Yes2|Included under gluten}}
|-
|sesame seeds
|{{Yes}} as of 2023<ref name=Sesame2021>{{cite web |url= https://www.congress.gov/bill/117th-congress/senate-bill/578/text |title= Food Allergy Safety, Treatment, Education, and Research Act of 2021 or the FASTER Act of 2021|date=4 April 2021 |website=Congress.gov|access-date=12 October 2021}}</ref>
|{{Yes}}
|{{Yes}}
|{{Yes}}
|{{Yes}}
|-
|mustard
|{{No}}
|{{Yes}}
|{{Yes}}
|{{No}}
|{{Yes}}
|-
|sulphites (not a [[true allergy]])
|{{No}}
|{{Yes}}
|{{Yes}}
|{{Yes}}, if >10&nbsp;mg/kg
|{{Yes}}, if >10&nbsp;mg/kg
|-
|celery
|{{No}}
|{{No}}
|{{Yes}}
|{{No}}
|{{Yes}}
|-
|[[Lupin bean|lupin]]
|{{No}}
|{{No}}
|{{Yes}}
|{{Yes}}
|{{Yes}}
|}
There are no labeling laws mandating declaration of the presence of trace amounts in the final product as a consequence of cross-contamination, except in Brazil.<ref name="ANVISA2016">{{cite web|title=Agência Nacional de Vigilância Sanitária Guia sobre Programa de Controle de Alergênicos|url=https://www.saude.rj.gov.br/comum/code/MostrarArquivo.php?C=MzIxOQ%2C%2C|publisher=Agência Nacional de Vigilância Sanitária (ANVISA)|date=2016|access-date=7 April 2018|language=pt|archive-url=https://web.archive.org/web/20180429222652/https://www.saude.rj.gov.br/comum/code/MostrarArquivo.php?C=MzIxOQ,,|archive-date=29 April 2018|url-status=dead}}</ref><ref name="FDA2004">{{cite web |url=http://www.cfsan.fda.gov/~dms/alrgact.html |publisher=FDA |title=Food Allergen Labeling and Consumer Protection Act of 2004 |date=August 2, 2004 |url-status=dead |archive-url=https://web.archive.org/web/20090528181345/http://www.cfsan.fda.gov/~dms/alrgact.html |archive-date=2009-05-28 }}</ref><ref name="EU2015">[https://www.food.gov.uk/sites/default/files/food-allergen-labelling-technical-guidance.pdf "Food allergen labelling and information requirements under the EU Food Information for Consumers Regulation No. 1169/2011: Technical Guidance"] {{Webarchive|url=https://web.archive.org/web/20170707062644/https://www.food.gov.uk/sites/default/files/food-allergen-labelling-technical-guidance.pdf |date=7 July 2017 }} (April 2015).</ref><ref name="FDAreadlabel2017" /><ref name="FSIS2017">{{cite web|title=Food Ingredients of Public Health Concern|url=https://www.fsis.usda.gov/wps/wcm/connect/09708e0b-1c79-43b4-99c4-78e408d01df1/35_IM_Ingredients_Health_Concern.pdf?MOD=AJPERES|archive-url=https://web.archive.org/web/20150729012550/http://www.fsis.usda.gov/wps/wcm/connect/09708e0b-1c79-43b4-99c4-78e408d01df1/35_IM_Ingredients_Health_Concern.pdf?MOD=AJPERES|url-status=dead|archive-date=29 July 2015|website=United States Department of Agriculture. Food Safety and Inspection Service.|access-date=16 February 2018|date=7 March 2017}}</ref><ref name="FSIS2016">{{cite web|title=Allergies and Food Safety|url=https://www.fsis.usda.gov/wps/portal/fsis/topics/food-safety-education/get-answers/food-safety-fact-sheets/food-labeling/allergies-and-food-safety/allergies-and-food-safety|archive-url=https://web.archive.org/web/20130915060328/http://www.fsis.usda.gov/wps/portal/fsis/topics/food-safety-education/get-answers/food-safety-fact-sheets/food-labeling/allergies-and-food-safety/allergies-and-food-safety|url-status=dead|archive-date=15 September 2013|website=United States Department of Agriculture. Food Safety and Inspection Service.|access-date=16 February 2018|date=1 December 2016}}</ref><ref name="Allen2014" /><ref name="FDAallergies2017" />

====Ingredients intentionally added====
In the United States, the [[Food Allergen Labeling and Consumer Protection Act]] of 2004 requires companies to disclose on the label whether a packaged food product contains any of these eight major food allergens, added intentionally: cow's milk, peanuts, eggs, shellfish, fish, tree nuts, soy and wheat.<ref name=FDA2004 /> The eight-ingredient list originated in 1999 from the World Health Organisation Codex Alimentarius Commission.<ref name=Allen2014 /> To meet labeling requirements, if an ingredient is derived from one of the required-label allergens, then it must either have its "food sourced name" in parentheses, for example, "Casein (milk)," or as an alternative, there must be a statement separate but adjacent to the ingredients list: "Contains milk" (and any other of the allergens with mandatory labeling).<ref name=FDA2004 /><ref name=FDAreadlabel2017>{{cite web|last=FDA|title=Have Food Allergies? Read the Label|website=[[Food and Drug Administration]] |url=https://www.fda.gov/ForConsumers/ConsumerUpdates/ucm254504.htm|archive-url=https://web.archive.org/web/20110514051624/http://www.fda.gov/ForConsumers/ConsumerUpdates/ucm254504.htm|url-status=dead|archive-date=14 May 2011|date=14 December 2017|access-date=14 January 2018}}</ref> The European Union requires listing for those eight major allergens plus molluscs, celery, mustard, lupin, sesame and sulfites.<ref name=EU2015 />

In 2018, the US [[Food and Drug Administration|FDA]] issued a request for information for the consideration of labeling for sesame to help protect people who have sesame allergies.<ref>{{cite web |url=https://www.fda.gov/news-events/press-announcements/statement-fda-commissioner-scott-gottlieb-md-fdas-new-consideration-labeling-sesame-allergies |archive-url=https://web.archive.org/web/20190603231316/https://www.fda.gov/news-events/press-announcements/statement-fda-commissioner-scott-gottlieb-md-fdas-new-consideration-labeling-sesame-allergies |url-status=dead |archive-date=3 June 2019 |title=Statement from FDA Commissioner Scott Gottlieb, M.D., on the FDA's new consideration of labeling for sesame allergies |date= 29 October 2018 |website=U.S. Food and Drug Administration |access-date=8 December 2019}}</ref> A decision was reached in November 2020 that food manufacturers voluntarily declare that when powdered sesame seeds are used as a previously unspecified spice or flavor, the label be changed to "spice (sesame)" or "flavor (sesame)."<ref name=Sesame2020>{{cite web |url=https://www.fda.gov/food/cfsan-constituent-updates/fda-issues-draft-guidance-industry-voluntary-disclosure-sesame-when-added-flavoring-or-spice |archive-url=https://web.archive.org/web/20201110155809/https://www.fda.gov/food/cfsan-constituent-updates/fda-issues-draft-guidance-industry-voluntary-disclosure-sesame-when-added-flavoring-or-spice |url-status=dead |archive-date=10 November 2020 |title=FDA Issues Draft Guidance for Industry on Voluntary Disclosure of Sesame When Added as Flavoring or Spice |date= 10 November 2020 |website=U.S. Food and Drug Administration |access-date=11 November 2020}}</ref>

Congress and the President passed a law in April 2021, the "FASTER Act", stipulating that labeling be mandatory, to be effect January 1, 2023, making it the ninth required food ingredient label.<ref name=SesameLaw2021>{{cite web |url= https://www.congress.gov/bill/117th-congress/senate-bill/578/text |title= Food Allergy Safety, Treatment, Education, and Research Act of 2021 or the FASTER Act of 2021|date=4 April 2021 |website=Congress.gov|access-date=5 March 2022}}</ref>

The Food Allergen Labeling and Consumer Protection Act of 2004 applies to packaged foods regulated by the FDA, which does not include poultry, most meats, certain egg products, and most alcoholic beverages.<ref name=FDAallergies2017 /> However, some meat, poultry, and egg processed products may contain allergenic ingredients. These products are regulated by the [[Food Safety and Inspection Service]], which requires that any ingredient be declared in the labeling only by its common or usual name. Neither the identification of the source of a specific ingredient in a parenthetical statement nor the use of statements to alert for the presence of specific ingredients, like "Contains: milk", are mandatory.<ref name="FSIS2017" /><ref name="FSIS2016" />  The act also does not apply to food prepared in restaurants.<ref name="pmid24505841">{{cite journal | vauthors = Roses JB | title = Food allergen law and the Food Allergen Labeling and Consumer Protection Act of 2004: falling short of true protection for food allergy sufferers | journal = Food and Drug Law Journal | volume = 66 | issue = 2 | pages = 225–42, ii | year = 2011 | pmid = 24505841 }}</ref><ref name="FDAFALCPAquestions">{{cite web|last=FDA|title=Food Allergen Labeling And Consumer Protection Act of 2004 Questions and Answers |website=[[Food and Drug Administration]] |url=https://www.fda.gov/Food/GuidanceRegulation/GuidanceDocumentsRegulatoryInformation/Allergens/ucm106890.htm |archive-url=https://web.archive.org/web/20130318054344/http://www.fda.gov/Food/GuidanceRegulation/GuidanceDocumentsRegulatoryInformation/Allergens/ucm106890.htm |url-status=dead |archive-date=18 March 2013 |date=18 July 2006|access-date=12 March 2018}}</ref> The EU Food Information for Consumers Regulation 1169/2011 – requires food businesses to provide allergy information on food sold unpackaged, for example, in catering outlets, deli counters, bakeries and sandwich bars.<ref>{{cite web |url=http://www.food.gov.uk/business-industry/allergy-guide |title=Allergy and intolerance: guidance for businesses |access-date=2014-12-12 |url-status=live |archive-url=https://web.archive.org/web/20141208003515/https://www.food.gov.uk/business-industry/allergy-guide |archive-date=2014-12-08 }}</ref>

In the United States, there is no federal mandate to address the presence of allergens in drug products, medicines, or cosmetics.<ref name="ShahSerajuddin2017">{{cite journal | vauthors = Shah AV, Serajuddin AT, Mangione RA | title = Making All Medications Gluten Free | journal = Journal of Pharmaceutical Sciences | volume = 107 | issue = 5 | pages = 1263–1268 | date = May 2018 | pmid = 29287928 | doi = 10.1016/j.xphs.2017.12.021 }}</ref>

====Trace amounts as a result of cross-contamination====
The value of allergen labeling other than for intentional ingredients is controversial. This concerns labeling for ingredients present unintentionally as a consequence of cross-contact or cross-contamination at any point along the food chain (during raw material transportation, storage or handling, due to shared equipment for processing and packaging, etc.).<ref name=Allen2014 /><ref name=FDAallergies2017>{{cite web|last=FDA|title=Food Allergies: What You Need to Know |website=[[Food and Drug Administration]] |url=https://www.fda.gov/Food/ResourcesForYou/Consumers/ucm079311.htm |archive-url=https://web.archive.org/web/20090607081658/http://www.fda.gov/Food/ResourcesForYou/Consumers/ucm079311.htm |url-status=dead |archive-date=7 June 2009 |date=18 December 2017|access-date=12 January 2018}}</ref> Experts in this field propose that if allergen labeling is to be useful to consumers, and healthcare professionals who advise and treat those consumers, ideally there should be agreement on which foods require labeling, threshold quantities below which labeling may be of no purpose, and validation of allergen detection methods to test and potentially recall foods that were deliberately or inadvertently contaminated.<ref name=Mills2004>{{cite journal | vauthors = Mills EN, Valovirta E, Madsen C, Taylor SL, Vieths S, Anklam E, Baumgartner S, Koch P, Crevel RW, Frewer L | display-authors = 6 | title = Information provision for allergic consumers--where are we going with food allergen labelling? | journal = Allergy | volume = 59 | issue = 12 | pages = 1262–1268 | date = December 2004 | pmid = 15507093 | doi = 10.1111/j.1398-9995.2004.00720.x | s2cid = 40395908 }}</ref><ref name=Taylor2015>{{cite book |vauthors=Taylor SL, Baumert JL |title=Food Allergy: Molecular Basis and Clinical Practice |chapter=Worldwide food allergy labeling and detection of allergens in processed foods |journal=Chem Immunol Allergy |volume=101 |pages=227–234 |year=2015 |pmid=26022883 |doi=10.1159/000373910 |series=Chemical Immunology and Allergy |isbn=978-3-318-02340-4 }}</ref>

Labeling regulations have been modified to provide for mandatory labeling of ingredients plus voluntary labeling, termed precautionary allergen labeling, also known as "may contain" statements, for possible, inadvertent, trace amount, cross-contamination during production.<ref name=Allen2014>{{cite journal | vauthors = Allen KJ, Turner PJ, Pawankar R, Taylor S, Sicherer S, Lack G, Rosario N, Ebisawa M, Wong G, Mills EN, Beyer K, Fiocchi A, Sampson HA | display-authors = 6 | title = Precautionary labelling of foods for allergen content: are we ready for a global framework? | journal = The World Allergy Organization Journal | volume = 7 | issue = 1 | pages = 10 | year = 2014 | pmid = 24791183 | pmc = 4005619 | doi = 10.1186/1939-4551-7-10 | doi-access = free }}</ref><ref name=DunnGalvin2015>{{cite journal | vauthors = DunnGalvin A, Chan CH, Crevel R, Grimshaw K, Poms R, Schnadt S, Taylor SL, Turner P, Allen KJ, Austin M, Baka A, Baumert JL, Baumgartner S, Beyer K, Bucchini L, Fernández-Rivas M, Grinter K, Houben GF, Hourihane J, Kenna F, Kruizinga AG, Lack G, Madsen CB, Clare Mills EN, Papadopoulos NG, Alldrick A, Regent L, Sherlock R, Wal JM, Roberts G | display-authors = 6 | title = Precautionary allergen labelling: perspectives from key stakeholder groups | journal = Allergy | volume = 70 | issue = 9 | pages = 1039–1051 | date = September 2015 | pmid = 25808296 | doi = 10.1111/all.12614 | s2cid = 18362869 | doi-access = free }}</ref> Precautionary allergen labeling can be confusing to consumers, especially as there can be many variations on the wording of the warning.<ref name=DunnGalvin2015 /><ref name=Zurzolo2016>{{cite journal | vauthors = Zurzolo GA, de Courten M, Koplin J, Mathai ML, Allen KJ | title = Is advising food allergic patients to avoid food with precautionary allergen labelling out of date? | journal = Current Opinion in Allergy and Clinical Immunology | volume = 16 | issue = 3 | pages = 272–277 | date = June 2016 | pmid = 26981748 | doi = 10.1097/ACI.0000000000000262 | s2cid = 21326926 }}</ref> Precautionary allergen labeling is optional in the United States.<ref>{{Cite news|url=https://www.nytimes.com/2019/01/28/health/food-allergies-children-labeling.html|title=Which Allergens Are in Your Food? You Can't Always Tell From the Labels| vauthors = Athas E |date=2019-01-28|work=The New York Times|access-date=2019-12-09|language=en-US|issn=0362-4331}}</ref> {{As of|2014}}, precautionary allergen labeling is regulated only in Switzerland, Japan, Argentina, and South Africa. Argentina decided to prohibit precautionary allergen labeling since 2010 and instead puts the onus on the manufacturer to control the manufacturing process and label only those allergenic ingredients known to be in the products. South Africa does not permit the use of precautionary allergen labeling, except when manufacturers demonstrate the potential presence of allergen due to cross-contact through a documented risk assessment and despite adherence to [[good manufacturing practice]].<ref name=Allen2014 /> In Australia and New Zealand there is a recommendation that precautionary allergen labeling be replaced by guidance from VITAL 2.0 (Vital Incidental Trace Allergen Labeling). A review identified "the eliciting dose for an allergic reaction in 1% of the population" as the threshold reference dose for certain foods (such as cow's milk, egg, peanut and other proteins) to provide food manufacturers with guidance for developing precautionary labeling and give consumers a better idea of what might be accidentally in a food product beyond "may contain."<ref name=Allen2014B>{{cite journal | vauthors = Allen KJ, Remington BC, Baumert JL, Crevel RW, Houben GF, Brooke-Taylor S, Kruizinga AG, Taylor SL | display-authors = 6 | title = Allergen reference doses for precautionary labeling (VITAL 2.0): clinical implications | journal = The Journal of Allergy and Clinical Immunology | volume = 133 | issue = 1 | pages = 156–164 | date = January 2014 | pmid = 23987796 | doi = 10.1016/j.jaci.2013.06.042 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Taylor SL, Baumert JL, Kruizinga AG, Remington BC, Crevel RW, Brooke-Taylor S, Allen KJ, Houben G | display-authors = 6 | title = Establishment of Reference Doses for residues of allergenic foods: report of the VITAL Expert Panel | journal = Food and Chemical Toxicology | volume = 63 | pages = 9–17 | date = January 2014 | pmid = 24184597 | doi = 10.1016/j.fct.2013.10.032 }}</ref> VITAL 2.0 was developed by the Allergen Bureau, a food industry sponsored, non-government organization.<ref>[http://allergenbureau.net/vital/ The VITAL Program] Allergen Bureau, Australia and New Zealand.</ref> The European Union has initiated a process to create labeling regulations for unintentional contamination but is not expected to publish such before 2024.<ref>{{cite journal | vauthors = Popping B, Diaz-Amigo C | title = European Regulations for Labeling Requirements for Food Allergens and Substances Causing Intolerances: History and Future | journal = Journal of AOAC International | volume = 101 | issue = 1 | pages = 2–7 | date = January 2018 | pmid = 29202901 | doi = 10.5740/jaoacint.17-0381 | doi-access = free }}</ref>

In Brazil, since April 2016, the declaration of the possibility of cross-contamination is mandatory when the product does not intentionally add any allergenic food or its derivatives, but the good manufacturing practices and allergen control measures adopted are not sufficient to prevent the presence of accidental trace amounts. These allergens include wheat, rye, barley, oats and their hybrids, crustaceans, eggs, fish, peanuts, soybean, milk of all species of mammalians, [[almond]]s, [[hazelnut]]s, [[cashew nut]]s, [[Brazil nut]]s, [[macadamia nut]]s, [[walnut]]s, [[pecan nut]]s, [[pistachio]]s, [[pine nut]]s, and [[chestnut]]s.<ref name="ANVISA2016"/>

===Genetically modified food===
There is a [[scientific consensus]] that available food derived from genetically modified crops poses no greater risk to human health than conventional food,<ref>{{cite journal | vauthors = Nicolia A, Manzo A, Veronesi F, Rosellini D | title = An overview of the last 10 years of genetically engineered crop safety research | journal = Critical Reviews in Biotechnology | volume = 34 | issue = 1 | pages = 77–88 | date = March 2014 | pmid = 24041244 | doi = 10.3109/07388551.2013.823595 | url = http://www.agrobio.org/bfiles/fckimg/Nicolia%202013.pdf | access-date = 2 January 2019 | url-status = dead | s2cid = 9836802 | archive-url = https://web.archive.org/web/20160917102103/http://www.agrobio.org/bfiles/fckimg/Nicolia%202013.pdf | archive-date = 17 September 2016 }}</ref><ref>{{cite web|url=http://www.fao.org/docrep/006/Y5160E/y5160e10.htm#P3_1651The|title=State of Food and Agriculture 2003–2004. Agricultural Biotechnology: Meeting the Needs of the Poor. Health and environmental impacts of transgenic crops|publisher=Food and Agriculture Organization of the United Nations|access-date=8 February 2016}}</ref><ref>{{cite book|url=http://www.nap.edu/read/23395/chapter/7#149|title=Genetically Engineered Crops: Experiences and Prospects|date=2016|publisher=The National Academies of Sciences, Engineering, and Medicine (US)|page=149|access-date=19 May 2016|doi=10.17226/23395|pmid=28230933|isbn=978-0-309-43738-7|last1=National Academies Of Sciences|first1=Engineering|author2=Division on Earth Life Studies|author3=Board on Agriculture Natural Resources|author4=Committee on Genetically Engineered Crops: Past Experience Future Prospects}}</ref> and a 2016 U.S. [[National Academy of Sciences]] report concluded that there is no relationship between consumption of genetically modified foods and the increase in prevalence of food allergies.<ref name=Dunn2017/> However, there are concerns that [[genetically modified food]]s, also described as foods sourced from [[genetically modified organism]]s, could be responsible for allergic reactions, and that the widespread acceptance of these types of foods may be responsible for what is a real or perceived increase in the percentage of people with allergies.<ref name=Lee2017>{{cite journal | vauthors = Lee TH, Ho HK, Leung TF | title = Genetically modified foods and allergy | journal = Hong Kong Medical Journal = Xianggang Yi Xue Za Zhi | volume = 23 | issue = 3 | pages = 291–295 | date = June 2017 | pmid = 28473652 | doi = 10.12809/hkmj166189 | doi-access = free | hdl = 10722/243781 | hdl-access = free }}</ref><ref name=Dunn2017>{{cite journal | vauthors = Dunn SE, Vicini JL, Glenn KC, Fleischer DM, Greenhawt MJ | title = The allergenicity of genetically modified foods from genetically engineered crops: A narrative and systematic review | journal = Annals of Allergy, Asthma & Immunology | volume = 119 | issue = 3 | pages = 214–222.e3 | date = September 2017 | pmid = 28890018 | doi = 10.1016/j.anai.2017.07.010 | doi-access = free }}</ref><ref name=Selb2017>{{cite journal | vauthors = Selb R, Wal JM, Moreno FJ, Lovik M, Mills C, Hoffmann-Sommergruber K, Fernandez A | title = Assessment of endogenous allergenicity of genetically modified plants exemplified by soybean - Where do we stand? | journal = Food and Chemical Toxicology | volume = 101 | pages = 139–148 | date = March 2017 | pmid = 28111299 | doi = 10.1016/j.fct.2017.01.014 | hdl-access = free | hdl = 10261/150576 }}</ref>

One concern is that genetic engineering could make an allergy-provoking food more allergic, meaning that smaller portions would suffice to set off a reaction.<ref name="Selb2017" /> Of the food currently{{when|date=September 2019}} in widespread use of genetically modified organisms, only soybeans are identified as a common allergen. However, for the soybean proteins known to trigger allergic reactions, there is more variation from strain to strain than between those and the genetically modified varieties.<ref name="Dunn2017" /> Another concern is that genes transferred from one species to another could introduce an allergen in a food not thought of as particularly allergenic. Research on an attempt to enhance the quality of soybean protein by adding genes from Brazil nuts was terminated when human volunteers known to have tree nut allergy reacted to the modified soybeans.<ref name=Lee2017/>

Prior to a new genetically modified food receiving government approval, certain criteria need to be met. These include: Is the donor species known to be allergenic? Does the amino acid sequence of the transferred proteins resemble the sequence of known allergenic proteins? Are the transferred proteins resistant to digestion – a trait shared by many allergenic proteins?<ref name="Dunn2017" /> Genes approved for animal use can be restricted from human consumption due to potential for allergic reactions. In 1998 StarLink brand corn restricted to animals was detected in the human food supply, leading to first a voluntary and then an FDA-mandated [[StarLink corn recall|recall]].<ref>{{cite journal | vauthors = Bucchini L, Goldman LR | title = Starlink corn: a risk analysis | journal = Environmental Health Perspectives | volume = 110 | issue = 1 | pages = 5–13 | date = January 2002 | pmid = 11781159 | pmc = 1240687 | doi = 10.1289/ehp.021105 }}</ref> There are requirements in some countries and recommendations in others that all foods containing genetically modified ingredients be so labeled, and that there be a post-launch monitoring system to report adverse effects (similar to the requirements in some countries for drug and dietary supplement reporting).<ref name="Lee2017" />

=== Restaurants ===
In the US, the FDA Food Code states that the person in charge in restaurants should have knowledge about major food allergens, cross-contacts, and symptoms of food allergy reactions. Restaurant staff, including wait staff and kitchen staff, may not be adequately informed about allergenic ingredients, or the risk of cross-contact when kitchen utensils used to prepare food may have been in previous contact with an allergenic food. The problem may be compounded when customers have a hard time describing their food allergies or when wait staff have a hard time understanding those with food allergies when taking an order.<ref>{{cite journal|vauthors=Wen H, Kwon J |title=Food Allergy Risk Communication in Restaurants |journal=Food Protection Trends |volume=35 |issue=5 |pages=372–383 |year=2016 |url=http://www.foodprotection.org/files/food-protection-trends/sep-oct-16-wen.pdf }}</ref>

=== Diagnosing issues ===
There exists both over-reporting and under-reporting of the prevalence of food allergies. Self-diagnosed perceptions of food allergy are greater than the rates of true food allergy because people confuse non-allergic intolerance with allergy, and also attribute non-allergy symptoms to an allergic response. Conversely, healthcare professionals treating allergic reactions on an out-patient or even hospitalized basis may not report all cases. Recent increases in reported cases may reflect a real change in incidence or an increased awareness on the part of healthcare professionals.<ref name="Hadley-2006">{{cite journal | vauthors = Hadley C | title = Food allergies on the rise? Determining the prevalence of food allergies, and how quickly it is increasing, is the first step in tackling the problem | journal = EMBO Reports | volume = 7 | issue = 11 | pages = 1080–1083 | date = November 2006 | pmid = 17077863 | pmc = 1679775 | doi = 10.1038/sj.embor.7400846 }}</ref>

==Social impact==
Food fear has a significant impact on quality of life.<ref name=Lange2014/><ref name=Velde2013/> For children with allergies, their quality of life is also affected by the actions of their peers. An increased occurrence of [[bullying]] has been observed, which can include threats or deliberate acts of forcing allergic children to contact foods that they must avoid or intentional contamination of allergen-free food.<ref>{{cite journal | vauthors = Fong AT, Katelaris CH, Wainstein B | title = Bullying and quality of life in children and adolescents with food allergy | journal = Journal of Paediatrics and Child Health | volume = 53 | issue = 7 | pages = 630–635 | date = July 2017 | pmid = 28608485 | doi = 10.1111/jpc.13570 | s2cid = 9719096 }}</ref> The social impacts of food allergies can carry over into adulthood.<ref>{{Cite web |date=2013-12-23 |title=The Social Impact of Food Allergies |url=https://www.huffpost.com/entry/living-with-food-allergies_b_4480918 |access-date=2023-01-01 |website=HuffPost |language=en}}</ref>

==Portrayal in media==
Media portrayals of food allergy in television and film are not accurate, often used for comedic effect or underplaying the potential severity of an allergic reaction.<ref name="Abo2017">{{cite journal | vauthors = Abo MM, Slater MD, Jain P | title = Using Health Conditions for Laughs and Health Policy Support: The Case of Food Allergies | journal = Health Communication | volume = 32 | issue = 7 | pages = 803–811 | date = July 2017 | pmid = 27436408 | doi = 10.1080/10410236.2016.1172292 | s2cid = 3858223 }}</ref> These [[trope (cinema)|tropes]] misinform the public and also contribute to how entertainment media will continue to wrongly portray food allergies in the future. Types of tropes: 1) characters have food allergies, providing a weakness that can be used to sabotage them. In the movie [[Parasite (2019 film)|''Parasite'']] a housekeeper is displaced by taking advantage of her peach allergy.<ref name=FARE /> In the animated film [[Peter Rabbit (film)|''Peter Rabbit'']], the farm owner is attacked by being pelted with blackberries, causing an anaphylactic reaction requiring emergency treatment with epinephrine. After many public protests, Sony Pictures and the ''Peter Rabbit'' director apologized for making light of food allergies.<ref>[https://www.nytimes.com/2018/02/12/arts/peter-rabbit-food-allergy.html Sony Apologizes for 'Peter Rabbit' Movie's Allergy Scene] New York Times, Jacey Fortrin, Feb 12, 2018.</ref> 2) Food allergy is used for comedic effect, such as in the movies [[Hitch (film)|''Hitch'']] and in television, Kelso's egg allergy in ''[[That '70s Show]].'' 3) Food allergies may be incorporated into characters who are also portrayed as annoying, weak and oversensitive, which can be taken as implying that their allergies are either not real or not potentially severe. In season 1, episode 16 of [[The Big Bang Theory (season 1)|''The Big Bang Theory'']] Howard Wolowitz deliberately consumes a peanut-containing food bar (and has a serious reaction) just to delay Leonard from returning to his apartment where a surprise birthday party is being arranged. 4) Any of these portrayals may underplay the potential severity of food allergy, some showing that [[Benadryl]] treatment is sufficient.<ref name=FARE>{{cite web |url=https://www.foodallergy.org/resources/how-media-portrays-food-allergies |title=How the Media Portrays Food Allergies |date= |website=Food Allergy Research and Education (FARE) |access-date=12 September 2022}}</ref> Viewing of humorous portrayals of food allergies has been shown to have a negative effect on related health policy support due to low perceived seriousness.<ref name="Abo2017"/>

==Research==
Several theories have been suggested to explain why certain individuals develop allergic sensitization instead of oral tolerance to food allergens. One such theory is the dual allergen hypothesis, which states that ingesting food allergens early on promotes oral tolerance while skin exposure leads to sensitization.<ref name="Iweala-2019"/> Instead of oral ingestion, skin barrier disruption in conditions like eczema, for instance, was suggested to cause allergic sensitization in animal and human infants.<ref name="Calvani-2020"/> Inhalation was recently proposed to be an additional sensitization route in the dual allergen hypothesis.<ref name="Kulis-2021"/> Another theory is the barrier regulation hypothesis, describing the role of [[Commensalism|commensal bacteria]] in preventing the development of food allergy by maintaining integrity of the [[Intestinal epithelium|intestinal epithelial barrier]].<ref name="Iweala-2019" /> Environmental and lifestyle factors, such as early life nutrition and antibiotic treatment, may contribute to food allergy prevalence by affecting gut microbial composition, and thus, intestinal immune homeostasis in infants and young children.<ref>{{cite journal | vauthors = Wesemann DR, Nagler CR | title = The Microbiome, Timing, and Barrier Function in the Context of Allergic Disease | journal = Immunity | volume = 44 | issue = 4 | pages = 728–738 | date = April 2016 | pmid = 27096316 | pmc = 4869964 | doi = 10.1016/j.immuni.2016.02.002 }}</ref>

A number of desensitization techniques are being studied.<ref>{{cite journal | vauthors = Nowak-Węgrzyn A, Sampson HA | title = Future therapies for food allergies | journal = The Journal of Allergy and Clinical Immunology | volume = 127 | issue = 3 | pages = 558–73; quiz 574–5 | date = March 2011 | pmid = 21277625 | pmc = 3066474 | doi = 10.1016/j.jaci.2010.12.1098 }}</ref> Areas of research include specific oral tolerance induction (also known as [[oral immunotherapy]]), and [[sublingual immunotherapy]]. The benefits of [[allergen immunotherapy]] for food allergies is unclear, thus is not recommended {{as of|2015|lc=yes}}.<ref name="NIH2015Imm" />

There is research on the effects of increasing intake of [[polyunsaturated fatty acid]]s during pregnancy, lactation, via infant formula and in early childhood on the subsequent risk of developing food allergies during infancy and childhood. From two reviews, maternal intake of [[omega-3 fatty acid|omega-3, long-chain fatty acids]] during pregnancy appeared to reduce the risks of medically diagnosed IgE-mediated allergy, eczema and food allergy per parental reporting in the first 12 months of life,<ref name=Best2016>{{cite journal | vauthors = Best KP, Gold M, Kennedy D, Martin J, Makrides M | title = Omega-3 long-chain PUFA intake during pregnancy and allergic disease outcomes in the offspring: a systematic review and meta-analysis of observational studies and randomized controlled trials | journal = The American Journal of Clinical Nutrition | volume = 103 | issue = 1 | pages = 128–143 | date = January 2016 | pmid = 26675770 | doi = 10.3945/ajcn.115.111104 | doi-access = free }}</ref><ref name=Gunaratne2015>{{cite journal | vauthors = Gunaratne AW, Makrides M, Collins CT | title = Maternal prenatal and/or postnatal n-3 long chain polyunsaturated fatty acids (LCPUFA) supplementation for preventing allergies in early childhood | journal = The Cochrane Database of Systematic Reviews | volume = 2015 | issue = 7 | pages = CD010085 | date = July 2015 | pmid = 26197477 | pmc = 8783748 | doi = 10.1002/14651858.CD010085.pub2 }}</ref> but the effects were not all sustained past 12 months.<ref name=Gunaratne2015 /> The reviews characterized the literature's evidence as inconsistent and limited.<ref name=Best2016 /><ref name=Gunaratne2015 /> Results when breastfeeding mothers were consuming a diet high in polyunsaturated fatty acids were inconclusive.<ref>{{cite journal | vauthors = Waidyatillake NT, Dharmage SC, Allen KJ, Lodge CJ, Simpson JA, Bowatte G, Abramson MJ, Lowe AJ | display-authors = 6 | title = Association of breast milk fatty acids with allergic disease outcomes-A systematic review | journal = Allergy | volume = 73 | issue = 2 | pages = 295–312 | date = February 2018 | pmid = 28869762 | doi = 10.1111/all.13300 | doi-access = free }}</ref> For infants, supplementing their diet with oils high in polyunsaturated fatty acids did not affect the risks of food allergies, eczema or asthma either as infants or into childhood.<ref>{{cite journal | vauthors = Schindler T, Sinn JK, Osborn DA | title = Polyunsaturated fatty acid supplementation in infancy for the prevention of allergy | journal = The Cochrane Database of Systematic Reviews | volume = 2016 | issue = 10 | pages = CD010112 | date = October 2016 | pmid = 27788565 | pmc = 6464137 | doi = 10.1002/14651858.CD010112.pub2 }}</ref>

There is research on [[probiotic]]s, [[prebiotic (nutrition)|prebiotic]]s and the combination of the two ([[synbiotics]]) as a means of treating or preventing infant and child allergies. From reviews, there appears to be a treatment benefit for eczema,<ref>{{cite journal | vauthors = Chang YS, Trivedi MK, Jha A, Lin YF, Dimaano L, García-Romero MT | title = Synbiotics for Prevention and Treatment of Atopic Dermatitis: A Meta-analysis of Randomized Clinical Trials | journal = JAMA Pediatrics | volume = 170 | issue = 3 | pages = 236–242 | date = March 2016 | pmid = 26810481 | doi = 10.1001/jamapediatrics.2015.3943 | doi-access = free }}</ref><ref name=Cuello2015>{{cite journal | vauthors = Cuello-Garcia CA, Brożek JL, Fiocchi A, Pawankar R, Yepes-Nuñez JJ, Terracciano L, Gandhi S, Agarwal A, Zhang Y, Schünemann HJ | display-authors = 6 | title = Probiotics for the prevention of allergy: A systematic review and meta-analysis of randomized controlled trials | journal = The Journal of Allergy and Clinical Immunology | volume = 136 | issue = 4 | pages = 952–961 | date = October 2015 | pmid = 26044853 | doi = 10.1016/j.jaci.2015.04.031 }}</ref><ref name=Osborn2013>{{cite journal | vauthors = Osborn DA, Sinn JK | title = Prebiotics in infants for prevention of allergy | journal = The Cochrane Database of Systematic Reviews | issue = 3 | pages = CD006474 | date = March 2013 | volume = 2013 | pmid = 23543544 | doi = 10.1002/14651858.CD006474.pub3 }}</ref> but not asthma, wheezing or rhinoconjunctivitis.<ref>{{cite journal | vauthors = Zuccotti G, Meneghin F, Aceti A, Barone G, Callegari ML, Di Mauro A, Fantini MP, Gori D, Indrio F, Maggio L, Morelli L, Corvaglia L | display-authors = 6 | title = Probiotics for prevention of atopic diseases in infants: systematic review and meta-analysis | journal = Allergy | volume = 70 | issue = 11 | pages = 1356–1371 | date = November 2015 | pmid = 26198702 | doi = 10.1111/all.12700 | doi-access = free }}</ref> The evidence was not consistent for preventing food allergies and this approach cannot yet be recommended.<ref name=Cuello2015 /><ref name=Osborn2013 /><ref>{{cite journal | vauthors = Zhang GQ, Hu HJ, Liu CY, Zhang Q, Shakya S, Li ZY | title = Probiotics for Prevention of Atopy and Food Hypersensitivity in Early Childhood: A PRISMA-Compliant Systematic Review and Meta-Analysis of Randomized Controlled Trials | journal = Medicine | volume = 95 | issue = 8 | pages = e2562 | date = February 2016 | pmid = 26937896 | pmc = 4778993 | doi = 10.1097/MD.0000000000002562 }}</ref><ref>{{cite journal | vauthors = de Silva D, Geromi M, Panesar SS, Muraro A, Werfel T, Hoffmann-Sommergruber K, Roberts G, Cardona V, Dubois AE, Halken S, Host A, Poulsen LK, Van Ree R, Vlieg-Boerstra BJ, Agache I, Sheikh A | display-authors = 6 | title = Acute and long-term management of food allergy: systematic review | journal = Allergy | volume = 69 | issue = 2 | pages = 159–167 | date = February 2014 | pmid = 24215577 | doi = 10.1111/all.12314 | s2cid = 206999857 | doi-access = free }}</ref>

The Food Standards Agency, in the United Kingdom, are in charge of funding research into food allergies and intolerance.<ref name="Hadley-2006" /> Since their founding in 1994 they have funded over 45 studies.<ref name="Hadley-2006" />&nbsp;In 2005 Europe created EuroPrevall, a multi-country project dedicated to research involving allergies.<ref name="Hadley-2006" />&nbsp;

== See also ==
* [[List of allergens]] (food and non-food)

== References ==
{{Reflist}}

;Notes
* {{cite book | vauthors = Nester EW, Anderson DG, Roberts Jr CE, Nester MT |chapter=Immunologic Disorders |title=Microbiology: A Human Perspective |publisher=McGraw-Hill |location=New York |year=2009 |pages=414–428 |edition=6th |ref={{harvid|Nester|2009}}}}
* {{cite book | vauthors = Sicherer SH |title=Understanding and Managing Your Child's Food Allergy |url=https://archive.org/details/understandingman00sich |url-access=registration |publisher=Johns Hopkins University Press |location=Baltimore |year=2006 }}

== External links ==
* [http://www.merckmanuals.com/home/immune_disorders/allergic_reactions_and_other_hypersensitivity_disorders/food_allergy.html Food Allergy], ''[[Merck Manual]]''
* {{cite web|url=http://www.nal.usda.gov/fnic/pubs/bibs/allergy.pdf|title=Food Allergies and Intolerances Resource List for Consumers|date=December 2010|publisher=Food and Nutrition Information Center, National Agricultural Library|access-date=15 August 2011|archive-date=6 August 2011|archive-url=https://web.archive.org/web/20110806123132/http://www.nal.usda.gov/fnic/pubs/bibs/allergy.pdf|url-status=dead}} – a collection of resources on the topic of food allergies and intolerances
* {{cite web | url = https://medlineplus.gov/foodallergy.html | publisher = U.S. National Library of Medicine | work = MedlinePlus | title = Food Allergy }}

{{Medical resources
| DiseasesDB      =
| ICD10           = {{ICD10|T|78|0|t|66}}
| ICD9            = {{ICD9|V15.01}}-{{ICD9|V15.05}}
| ICDO            =
| OMIM            = 147050
| MedlinePlus     = 000817
| eMedicineSubj   = med
| eMedicineTopic  = 806
| MeshID          = D005512
| SNOMED CT       = 414285001
}}

{{Food science}}
{{Allergic conditions}}
{{Hypersensitivity and autoimmune diseases}}
{{Authority control}}
{{Portal bar|Food|Medicine}}

{{DEFAULTSORT:Food Allergy}}
[[Category:Food allergies| ]]
[[Category:Wikipedia medicine articles ready to translate]]
[[Category:Wikipedia emergency medicine articles ready to translate]]