Editing Food intolerance (section)

==Research directions==
{{more medical citations needed|section|date=October 2023}}
[[FODMAP]]s are fermentable [[oligosaccharide|oligo-]], [[disaccharide|di-]], [[monosaccharides]] and [[polyol]]s, which are poorly absorbed in the small intestine and subsequently fermented by the bacteria in the distal [[small intestine|small]] and proximal [[large intestine]]. This is a normal phenomenon, common to everyone. The resultant production of gas potentially results in bloating and [[flatulence]].<ref name="Gibson2010">{{cite journal|author=Peter R Gibson|author2=Susan J Shepherd|s2cid=20666740|name-list-style=amp|title=Evidence-based dietary management of functional gastrointestinal symptoms: The FODMAP approach|journal=Journal of Gastroenterology and Hepatology|year=2010|volume=25|pages=252–258|doi=10.1111/j.1440-1746.2009.06149.x|pmid=20136989|issue=2|doi-access=free}}</ref> Although FODMAPs can produce certain digestive discomfort in some people, not only do they not cause intestinal inflammation, but they avoid it, because they produce beneficial alterations in the intestinal flora that contribute to maintain the good health of the colon.<ref name="MakhariaCatassi2015">{{cite journal| vauthors=Makharia A, Catassi C, Makharia GK| title=The Overlap between Irritable Bowel Syndrome and Non-Celiac Gluten Sensitivity: A Clinical Dilemma. | journal=Nutrients | year= 2015 | volume= 7 | issue= 12 | pages= 10417–26 | pmid=26690475 | doi=10.3390/nu7125541 | pmc=4690093 | type=Review | doi-access=free }}</ref><ref name="GreerOKeefe2015">{{cite journal| vauthors=Greer JB, O'Keefe SJ| title=Microbial induction of immunity, inflammation, and cancer. | journal=Front Physiol | year= 2011 | volume= 1 | pages= 168 | pmid=21423403 | doi=10.3389/fphys.2010.00168 | pmc=3059938 | type=Review | doi-access=free }}</ref><ref name="AndohTsujikawa2003">{{cite journal|vauthors=Andoh A, Tsujikawa T, Fujiyama Y| title=Role of dietary fiber and short-chain fatty acids in the colon. | journal=Curr Pharm Des | year= 2003 | volume= 9 | issue= 4 | pages= 347–58 | pmid=12570825 | type=Review | doi=10.2174/1381612033391973 }}</ref> FODMAPs are not the cause of irritable bowel syndrome nor other [[functional gastrointestinal disorder]]s, but rather a person develops symptoms when the underlying bowel response is exaggerated or abnormal.<ref name="Gibson2010" /> A [[low-FODMAP diet]] might help to improve short-term digestive symptoms in adults with irritable bowel syndrome,<ref name="TurcoSalvatore2018">{{cite journal| vauthors=Turco R, Salvatore S, Miele E, Romano C, Marseglia GL, Staiano A| title=Does a low-FODMAPs diet reduce symptoms of functional abdominal pain disorders? A systematic review in adult and paediatric population, on behalf of Italian Society of Pediatrics. | journal=Ital J Pediatr | year= 2018 | volume= 44 | issue= 1 | pages= 53 | pmid=29764491 | doi=10.1186/s13052-018-0495-8 | pmc=5952847 | type=Systematic Review | doi-access=free }}</ref><ref name=Staudacher>{{cite journal |vauthors=Staudacher HM, Irving PM, Lomer MC, Whelan K |title=Mechanisms and efficacy of dietary FODMAP restriction in IBS |journal=Nat Rev Gastroenterol Hepatol |volume=11 |issue=4 |pages=256–66 | date=April 2014 |pmid=24445613 |doi=10.1038/nrgastro.2013.259 |s2cid=23001679 |type=Review |quote=An emerging body of research now demonstrates the efficacy of fermentable carbohydrate restriction in IBS.&nbsp;[...]&nbsp;However, further work is urgently needed both to confirm clinical efficacy of fermentable carbohydrate restriction in a variety of clinical subgroups and to fully characterize the effect on the gut microbiota and the colonic environ¬ment. Whether the effect on luminal bifidobacteria is clinically relevant, preventable, or long lasting, needs to be investigated. The influence on nutrient intake, dietary diversity, which might also affect the gut microbiota,137 and quality of life also requires further exploration as does the possible economic effects due to reduced physician contact and need for medication. Although further work is required to confirm its place in IBS and functional bowel disorder clinical pathways, fermentable carbohydrate restriction is an important consideration for future national and international IBS guidelines. }}</ref><ref name="MarshEslick2015">{{cite journal |vauthors=Marsh A, Eslick EM, Eslick GD |title=Does a diet low in FODMAPs reduce symptoms associated with functional gastrointestinal disorders? A comprehensive systematic review and meta-analysis |journal=Eur J Nutr |volume= 55|issue= 3|pages= 897–906|year=2015 |pmid=25982757 |doi=10.1007/s00394-015-0922-1 |s2cid=206969839 }}</ref><ref name=Rao2015>{{cite journal |vauthors=Rao SS, Yu S, Fedewa A |title=Systematic review: dietary fibre and FODMAP-restricted diet in the management of constipation and irritable bowel syndrome |journal=Aliment. Pharmacol. Ther. |volume=41 |issue=12 |pages=1256–70 |year=2015 |pmid=25903636 |doi=10.1111/apt.13167|s2cid=27558785 |doi-access=free }}</ref> but its long-term follow-up can have negative effects because it causes a detrimental impact on the [[gut microbiota]] and [[metabolome]].<ref name="TuckMuir2014">{{cite journal|last1=Tuck|first1=CJ|last2=Muir|first2=JG|last3=Barrett|first3=JS|last4=Gibson|first4=PR|title=Fermentable oligosaccharides, disaccharides, monosaccharides and polyols: role in irritable bowel syndrome|journal=Expert Rev Gastroenterol Hepatol|date=2014|volume=8|issue=7|pages=819–834|doi=10.1586/17474124.2014.917956|pmid=24830318|s2cid=28811344 }}</ref><ref name=Staudacher /><ref name=Rao2015/><ref name="HeimanGreenway2016">{{cite journal| vauthors=Heiman ML, Greenway FL| title=A healthy gastrointestinal microbiome is dependent on dietary diversity. | journal=Mol Metab | year= 2016 | volume= 5 | issue= 5 | pages= 317–320 | pmid=27110483 | doi=10.1016/j.molmet.2016.02.005 | pmc=4837298 | type=Review }}</ref> It should only be used for short periods of time and under the advice of a specialist.<ref name="StaudacherWhelan2017">{{cite journal| vauthors=Staudacher HM, Whelan K| title=The low FODMAP diet: recent advances in understanding its mechanisms and efficacy in IBS. | journal=Gut | year= 2017 | volume= 66 | issue= 8 | pages= 1517–1527 | pmid=28592442 | doi=10.1136/gutjnl-2017-313750 | s2cid=3492917 | type=Review | url=https://kclpure.kcl.ac.uk/portal/en/publications/the-low-fodmap-diet(c7f6c885-e206-4fa4-8206-576e70bd3d59).html }}</ref> More studies are needed to assess the true impact of this diet on health.<ref name=Staudacher /><ref name=Rao2015/>

Also, when a low FODMAP diet is used without a previous complete medical evaluation can cause serious health risks. It can ameliorate and mask the digestive symptoms of serious diseases, such as [[celiac disease]], [[inflammatory bowel disease]] and [[colon cancer]], avoiding their correct diagnosis and therapy.<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=4 June 2018|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| quote= Celiac disease (CD) is a chronic, multiple-organ autoimmune disease that affects the small intestine&nbsp;[...]&nbsp;Patients with (long-term untreated) celiac disease have an elevated risk for benign and malignant complications, and mortality. * Cancer – highest risk in the initial years after diagnosis, decreases to (near) normal risk by the fifth year [96], overall risk increment 1.35. * Malignant lymphomas * Small-bowel adenocarcinoma * Oropharyngeal tumors * Unexplained infertility (12%) * Impaired bone health and growth (osteoporosis 30–40%) * Bone fractures – increased risk 35% for classically symptomatic celiac disease patients [97,98] * The mortality risk is elevated in adult celiac patients, due to an increased risk for fatal malignancy (hazard ratio, 1.31; 95% confidence intervals, 1.13 to 1.51 in one study) [64] * Adverse pregnancy outcome [99]&nbsp;[...]&nbsp;Diagnostic tests&nbsp;[...]&nbsp;Biopsies must be taken when patients are on a gluten-containing diet.}}</ref>
<ref name="Barrett2017">{{cite journal| author=Barrett JS| title=How to institute the low-FODMAP diet. | journal=J Gastroenterol Hepatol | year= 2017 | volume= 32 | issue=Suppl 1 | pages= 8–10 | pmid=28244669 | doi=10.1111/jgh.13686 |type=Review | quote= Common symptoms of IBS are bloating, abdominal pain, excessive flatus, constipation, diarrhea, or alternating bowel habit. These symptoms, however, are also common in the presentation of coeliac disease, inflammatory bowel disease, defecatory disorders, and colon cancer. Confirming the diagnosis is crucial so that appropriate therapy can be undertaken. Unfortunately, even in these alternate diagnoses, a change in diet restricting FODMAPs may improve symptoms and mask the fact that the correct diagnosis has not been made. This is the case with coeliac disease where a low-FODMAP diet can concurrently reduce dietary gluten, improving symptoms, and also affecting coeliac diagnostic indices.3,4 Misdiagnosis of intestinal diseases can lead to secondary problems such as nutritional deficiencies, cancer risk, or even mortality in the case of colon cancer.| doi-access=free }}</ref> This is especially relevant in the case of celiac disease. Since the consumption of [[gluten]] is suppressed or reduced with a low-FODMAP diet, the improvement of the digestive symptoms with this diet may not be related to the withdrawal of the FODMAPs, but of gluten, indicating the presence of an unrecognized celiac disease, avoiding its diagnosis and correct treatment, with the consequent risk of several serious health complications, including various types of cancer.<ref name="Barrett2017" />

A three-month randomized, blinded, controlled trial on people with irritable bowel syndrome found that those who withdrew from the diet the foods to which they had shown an increased IgG antibody response experienced an improvement in their symptoms.<ref name="IkechiFischer2017">{{cite journal|vauthors=Ikechi R, Fischer BD, DeSipio J, Phadtare S| title=Irritable Bowel Syndrome: Clinical Manifestations, Dietary Influences, and Management. | journal= Healthcare| year= 2017 | volume= 5 | issue= 2 | pages=  21| pmid=28445436 | doi=10.3390/healthcare5020021 | pmc=5492024 | doi-access=free }}</ref>  In individuals with Crohn's disease and ulcerative colitis food-specific-IgG-based elimination diets have been shown to be effective at reducing symptoms.<ref>{{Cite journal |last1=Bentz |first1=S. |last2=Hausmann |first2=M. |last3=Piberger |first3=H. |last4=Kellermeier |first4=S. |last5=Paul |first5=S. |last6=Held |first6=L. |last7=Falk |first7=W. |last8=Obermeier |first8=F. |last9=Fried |first9=M. |last10=Schölmerich |first10=J. |last11=Rogler |first11=G. |date=2010 |title=Clinical relevance of IgG antibodies against food antigens in Crohn's disease: a double-blind cross-over diet intervention study |url=https://pubmed.ncbi.nlm.nih.gov/20130407 |journal=Digestion |volume=81 |issue=4 |pages=252–264 |doi=10.1159/000264649 |issn=1421-9867 |pmid=20130407|s2cid=9556315 }}</ref><ref>{{Cite journal |last1=Jian |first1=Liu |last2=Anqi |first2=He |last3=Gang |first3=Liu |last4=Litian |first4=Wang |last5=Yanyan |first5=Xu |last6=Mengdi |first6=Wang |last7=Tong |first7=Liu |date=2018-08-16 |title=Food Exclusion Based on IgG Antibodies Alleviates Symptoms in Ulcerative Colitis: A Prospective Study |url=https://pubmed.ncbi.nlm.nih.gov/29788288 |journal=Inflammatory Bowel Diseases |volume=24 |issue=9 |pages=1918–1925 |doi=10.1093/ibd/izy110 |issn=1536-4844 |pmid=29788288}}</ref><ref>{{Cite journal |last1=Jones |first1=V. A. |last2=Dickinson |first2=R. J. |last3=Workman |first3=E. |last4=Wilson |first4=A. J. |last5=Freeman |first5=A. H. |last6=Hunter |first6=J. O. |date=1985-07-27 |title=Crohn's disease: maintenance of remission by diet |url=https://pubmed.ncbi.nlm.nih.gov/2862371 |journal=Lancet |volume=2 |issue=8448 |pages=177–180 |doi=10.1016/s0140-6736(85)91497-7 |issn=0140-6736 |pmid=2862371|s2cid=21174037 }}</ref>

[[Intestinal permeability#Clinical significance|Increased intestinal permeability]], so called [[Intestinal permeability|leaky gut]], has been linked to food allergies<ref name="pmid16292078">{{cite journal |author=Heyman M |title=Gut barrier dysfunction in food allergy |journal=Eur J Gastroenterol Hepatol |volume=17 |issue=12 |pages=1279–85 |date=December 2005 |pmid=16292078 |doi= 10.1097/00042737-200512000-00003|s2cid=21021624 }}</ref> and some food intolerances.<ref name="pmid12394645">{{cite journal |vauthors=Baumgart DC, Dignass AU |title=Intestinal barrier function |journal=Current Opinion in Clinical Nutrition and Metabolic Care |volume=5 |issue=6 |pages=685–94 |date=November 2002 |pmid=12394645 |doi=10.1097/00075197-200211000-00012|s2cid=2326543 }}</ref><ref name="pmid19148789">{{cite journal |vauthors=Bjarnason I, Takeuchi K |title=Intestinal permeability in the pathogenesis of NSAID-induced enteropathy |journal=J. Gastroenterol. |volume=44 |pages=23–9 |year=2009 |issue=Suppl 19 |pmid=19148789 |doi=10.1007/s00535-008-2266-6 |s2cid=24383744 }}</ref> Research is currently focussing on specific conditions<ref name="pmid18806699">{{cite journal |author=Fedorak RN |title=Understanding why probiotic therapies can be effective in treating IBD |journal=J. Clin. Gastroenterol. |volume=42 Suppl 3 Pt 1 |pages=S111–5 |date=September 2008 |pmid=18806699 |doi=10.1097/MCG.0b013e31816d922c |s2cid=6855166 }}</ref><ref name="pmid18621505">{{cite journal |vauthors=Salvatore S, Hauser B, Devreker T, Arrigo S, Vandenplas Y |title=Chronic enteropathy and feeding in children: an update |journal=Nutrition |volume=24 |issue=11–12 |pages=1205–16 |year=2008 |pmid=18621505 |doi=10.1016/j.nut.2008.04.011 }}</ref><ref name="pmid17245093">{{cite book |vauthors=Gibbons T, Fuchs GJ |chapter=Chronic Enteropathy: Clinical Aspects |title=Nutrition Support for Infants and Children at Risk |s2cid=32663610 |volume=59 |pages=89–101; discussion 102–4 |year=2007 |pmid=17245093 |doi=10.1159/000098529 |series=Series Set, 2007 |isbn=978-3-8055-8194-3}}</ref> and effects of certain food constituents.<ref name="pmid17973645">{{cite journal |vauthors=Hamer HM, Jonkers D, Venema K, Vanhoutvin S, Troost FJ, Brummer RJ |title=Review article: the role of butyrate on colonic function |journal=Aliment. Pharmacol. Ther. |volume=27 |issue=2 |pages=104–19 |date=January 2008 |pmid=17973645 |doi=10.1111/j.1365-2036.2007.03562.x |s2cid=22698080 |doi-access= }}</ref><ref name="pmid17951508">{{cite journal |author=Veereman G |title=Pediatric applications of inulin and oligofructose |journal=J. Nutr. |volume=137 |issue=11 Suppl |pages=2585S–2589S |date=November 2007 |pmid=17951508 |doi= 10.1093/jn/137.11.2585S|doi-access=free }}</ref><ref name="pmid18931598">{{cite journal |author=Vanderhoof JA |title=Probiotics in allergy management |journal=J. Pediatr. Gastroenterol. Nutr. |volume=47 |pages=S38–40 |date=November 2008 |issue=Suppl 2 |pmid=18931598 |doi=10.1097/01.mpg.0000338810.74933.c1 |s2cid=9220248 |doi-access=free }}</ref> At present there are a number of ways to limit the increased permeability, but additional studies are required to assess if this approach reduces the prevalence and severity of specific conditions.<ref name="pmid19148789"/><ref name="pmid17973645"/>