How do dietary intolerances affect the symptoms of irritable bowel syndrome (IBS)?

Updated: Dec 11, 2019
  • Author: Jenifer K Lehrer, MD; Chief Editor: BS Anand, MD  more...
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Bloating and distention may also occur from intolerance to dietary fats. Reflex-mediated small bowel gas clearance is more impaired by the ingestion of lipids in patients with irritable bowel syndrome than in patients without the disorder.

Studies of elimination and challenge diets have suggested that poorly absorbed short-chain carbohydrates, in the form of fructose and fructans, may create symptoms among adult patients with irritable bowel syndrome, as measured by a visual analogue scale. [20] Fructans have also been found to exacerbate the symptoms (abdominal pain, bloating, hydrogen production) in a subset of children with irritable bowel syndrome, but fructan sensitivity could not be identified on the basis of baseline gastrointestinal symptoms, dietary intake, psychosocial factors, or gas production. [21]

Evidence exists showing an association between functional variants in the sucrase-isomaltase (SI) gene and an increased risk of irritable bowel syndrome. In one study, investigators sequenced SI exons in seven familial cases, as well as screened for four congenital sucrase-isomaltase deficiency (CSID) mutations and a common SI coding polymorphism in a multicenter cohort comprised of 1887 patients and control subjects, and found that individuals affected by the SI mutations that code for defective or enzymatic activity in disaccharides had a predisposition to irritable bowel syndrome. [22] Similarly, another multinational genotype study of 2207 patients indicates that there is an increased prevalence of rare sucrase-isomaltase pathogenic variants in those affected by irritable bowel syndrome. [23]

Research suggests that neuronal degeneration and myenteric plexus lymphocytosis may exist in the proximal jejunum. Additionally, colonic lymphocytosis and enteroendocrine cell hyperplasia have been demonstrated in some patients.


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