Editing Food intolerance (section)

==Causes==

Reactions to chemical components of the diet may be more common than true food allergies,{{Citation needed|date=April 2009}} although there is no evidence to support this. They are caused by various organic chemicals occurring naturally in a wide variety of foods, animal and vegetable, more often than to food additives, preservatives, colourings and flavourings, such as [[Sulfite food and beverage additives|sulfite]]s or dyes.<ref name="pmid18971901"/> Both natural and artificial ingredients may cause adverse reactions in sensitive people if consumed in sufficient amounts, the degree of sensitivity varying between individuals.

Pharmacological responses to naturally occurring compounds in food, or chemical intolerance, can occur in individuals from both allergic and non-allergic family backgrounds. Symptoms may begin at any age, and may develop quickly or slowly. Triggers may range from a viral infection or illness to environmental chemical exposure. Chemical intolerance occurs more commonly in women, which may be because of hormone differences, as many food chemicals mimic hormones.{{Citation needed|date=May 2014}}

A deficiency in digestive enzymes can also cause some types of food intolerances. [[Lactose intolerance]] is a result of the body not producing sufficient [[lactase]] to digest the lactose in milk;<ref name="pmid16951027">{{cite journal |author=Heyman MB |title=Lactose intolerance in infants, children, and adolescents |journal=Pediatrics |volume=118 |issue=3 |pages=1279–86 |date=September 2006 |pmid=16951027 |doi=10.1542/peds.2006-1721 |last2=Committee On |first2=Nutrition|s2cid=2996092 |doi-access= }}</ref><ref name="pmid9742907">{{cite journal |vauthors=Srinivasan R, Minocha A |title=When to suspect lactose intolerance. Symptomatic, ethnic, and laboratory clues |journal=Postgrad Med |volume=104 |issue=3 |pages=109–11, 115–6, 122–3 |date=September 1998 |pmid=9742907 |doi=10.3810/pgm.1998.09.577 |url=http://www.postgradmed.com/index.php?art=pgm_09_1998%3Farticle%3D577 |access-date=16 April 2009 |archive-date=19 February 2021 |archive-url=https://web.archive.org/web/20210219135026/https://www.tandfonline.com/toc/ipgm20/current |url-status=dead |url-access=subscription }}</ref> dairy foods which are lower in lactose, such as cheese, are less likely to trigger a reaction in this case. Another carbohydrate intolerance caused by enzyme deficiency is [[hereditary fructose intolerance]].

[[Celiac disease]], an autoimmune disorder caused by an immune response to the protein gluten, results in gluten intolerance and can lead to temporary lactose intolerance.<ref name="pmid16313685">{{cite journal |vauthors=McGough N, Cummings JH |title=Coeliac disease: a diverse clinical syndrome caused by intolerance of wheat, barley and rye |journal=Proc Nutr Soc |volume=64 |issue=4 |pages=434–50 |date=November 2005 |pmid=16313685 |doi= 10.1079/PNS2005461|doi-access=free }}</ref><ref name="pmid15137480">{{cite journal |author=Rousset H |title=[A great imitator for the allergologist: intolerance to gluten] |language=fr |journal=Eur Ann Allergy Clin Immunol |volume=36 |issue=3 |pages=96–100 |date=March 2004 |pmid=15137480 }}</ref>

The most widely distributed naturally occurring food chemical capable of provoking reactions is [[salicylate]],<ref name="pmid16247191"/> although [[tartrazine]] and [[benzoic acid]] are well recognised in susceptible individuals.<ref name="pmid17218045">{{cite journal |author=Elhkim MO |title=New considerations regarding the risk assessment on Tartrazine An update toxicological assessment, intolerance reactions and maximum theoretical daily intake in France |journal=Regul. Toxicol. Pharmacol. |volume=47 |issue=3 |pages=308–16 |date=April 2007 |pmid=17218045 |doi=10.1016/j.yrtph.2006.11.004 |name-list-style=vanc|author2=Héraud F |author3=Bemrah N |display-authors=3 |last4=Gauchard |first4=Françoise |last5=Lorino |first5=Tristan |last6=Lambré |first6=Claude |last7=Frémy |first7=Jean Marc |last8=Poul |first8=Jean-Michel}}</ref><ref name="pmid15491435">{{cite journal |vauthors=Nettis E, Colanardi MC, Ferrannini A, Tursi A |title=Sodium benzoate-induced repeated episodes of acute urticaria/angio-oedema: randomized controlled trial |journal=Br. J. Dermatol. |volume=151 |issue=4 |pages=898–902 |date=October 2004 |pmid=15491435 |doi=10.1111/j.1365-2133.2004.06095.x |s2cid=22547849 }}</ref><ref name="pmid11251628">{{cite journal |vauthors=Worm M, Vieth W, Ehlers I, Sterry W, Zuberbier T |title=Increased leukotriene production by food additives in patients with atopic dermatitis and proven food intolerance |journal=Clin. Exp. Allergy |volume=31 |issue=2 |pages=265–73 |date=February 2001 |pmid=11251628 |doi= 10.1046/j.1365-2222.2001.00979.x|s2cid=33634326 }}</ref> Benzoates and salicylates occur naturally in many foods, including fruits, juices, vegetables, spices, herbs, nuts, tea, wines, and coffee. [[Salicylate sensitivity]] causes reactions to aspirin and other NSAIDs, and also in foods which naturally contain salicylates, such as cherries.

Other natural chemicals which commonly cause reactions and cross reactivity include [[amines]], [[nitrates]], [[sulphites]] and some antioxidants. Chemicals involved in aroma and flavour are often suspect.<ref name="pmid17490952"/><ref name="pmid10413828">{{cite journal |vauthors=Schnyder B, Pichler WJ |title=[Food intolerance and food allergy] |language=de |journal=Schweiz Med Wochenschr |volume=129 |issue=24 |pages=928–33 |date=June 1999 |pmid=10413828 }}</ref><ref name="pmid12657413">{{cite journal |vauthors=Millichap JG, Yee MM |title=The diet factor in pediatric and adolescent migraine |journal=Pediatr. Neurol. |volume=28 |issue=1 |pages=9–15 |date=January 2003 |pmid=12657413 |doi= 10.1016/S0887-8994(02)00466-6}}</ref><ref name="pmid8795668">{{cite journal |vauthors=Hodge L, Yan KY, Loblay RL |title=Assessment of food chemical intolerance in adult asthmatic subjects |journal=Thorax |volume=51 |issue=8 |pages=805–9 |date=August 1996 |pmid=8795668 |pmc=472547 |doi= 10.1136/thx.51.8.805}}</ref>

The classification or avoidance of foods based on botanical families bears no relationship to their chemical content and is not relevant in the management of food intolerance.{{Citation needed|date=May 2014}}

Salicylate-containing foods include apples, citrus fruits, strawberries, tomatoes, and wine, while reactions to chocolate, cheese, bananas, avocado, tomato or wine point to amines as the likely food chemical. Thus, exclusion of single foods does not necessarily identify the chemical responsible as several chemicals can be present in a food, the patient may be sensitive to multiple food chemicals and reaction more likely to occur when foods containing the triggering substance are eaten in a combined quantity that exceeds the patient's sensitivity thresholds. People with food sensitivities have different sensitivity thresholds, and so more sensitive people will react to much smaller amounts of the substance.<ref name = "Clarke">
{{cite journal |author=Clarke L |year=1996 |title=The dietary management of food allergy and food intolerance in children and adults |journal=Aust J Nutr Diet |volume=53 |issue=3 |pages=89–98 |issn=1032-1322 |name-list-style=vanc|author2=McQueen J |display-authors=2 |author3=<Please add first missing authors to populate metadata.>}}</ref><ref name="pmid18594978" /><ref name="pmid17490952" /><ref name="pmid12657413" /><ref name="pmid8795668"/><ref name="pmid17361633">
{{cite journal |vauthors=Layer P, Keller J |title=[Therapy of functional bowel disorders] |language=de |journal=Praxis |volume=96 |issue=9 |pages=323–6 |year=2007 |pmid=17361633 |doi=10.1024/1661-8157.96.9.323}}
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{{cite journal |vauthors=Parker G, Watkins T |title=Treatment-resistant depression: when antidepressant drug intolerance may indicate food intolerance |journal=The Australian and New Zealand Journal of Psychiatry |volume=36 |issue=2 |pages=263–5 |year=2002 |pmid=11982551 |doi=10.1046/j.1440-1614.2002.00978.x|s2cid=46611658 }}
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{{cite journal |author=Iacono G |title=Food intolerance and chronic constipation: manometry and histology study |journal=European Journal of Gastroenterology & Hepatology |volume=18 |issue=2 |pages=143–50 |year=2006 |pmid=16394795 |doi=10.1097/00042737-200602000-00006 |name-list-style=vanc|author2=Bonventre S |author3=Scalici C |display-authors=3 |last4=Maresi |first4=Emiliano |last5=Prima |first5=Lidia Di |last6=Soresi |first6=Maurizio |last7=Ges?? |first7=Giuseppe Di |last8=Noto |first8=Davide |last9=Carroccio |first9=Antonio|s2cid=20007207 |hdl=10447/4967 |hdl-access=free }}
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{{cite journal |author=Asero R |title=Food additives intolerance: does it present as perennial rhinitis? |journal=Current Opinion in Allergy and Clinical Immunology |volume=4 |issue=1 |pages=25–9 |year=2004 |pmid=15090915 |doi=10.1097/00130832-200402000-00006|s2cid=21383210 }}
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{{cite journal |vauthors=Semeniuk J, Kaczmarski M |title=Gastroesophageal reflux (GER) in children and adolescents with regard to food intolerance |journal=Adv Med Sci |volume=51 |pages=321–6 |year=2006 |pmid=17357334 }}</ref>