Gluten-Free Diet Reduces Symptoms, Particularly Diarrhea, in Patients With Irritable Bowel Syndrome and Antigliadin IgG

Background & aims: Many patients with irritable bowel syndrome (IBS) perceive that their symptoms are triggered by wheat-containing foods. We assessed symptoms and gastrointestinal transit before and after a gluten-free diet (GFD) in unselected patients with IBS and investigated biomarkers associated with symptoms.

Methods: We performed a prospective study of 50 patients with IBS (ROME III, all subtypes), with and without serologic reactivity to gluten (antigliadin IgG and IgA), and 25 healthy subjects (controls) at a university hospital in Hamilton, Ontario, Canada, between 2012 and 2016. Gastrointestinal transit, gut symptoms, anxiety, depression, somatization, dietary habits, and microbiota composition were studied before and after 4 weeks of a GFD. HLA-DQ2/DQ8 status was determined. GFD compliance was assessed by a dietitian and by measuring gluten peptides in stool.

Results: There was no difference in symptoms among patients at baseline, but after the GFD, patients with antigliadin IgG and IgA reported less diarrhea than patients without these antibodies (P = .03). Compared with baseline, IBS symptoms improved in 18 of 24 patients (75%) with antigliadin IgG and IgA and in 8 of 21 patients (38%) without the antibodies. Although constipation, diarrhea, and abdominal pain were reduced in patients with antigliadin IgG and IgA, only pain decreased in patients without these antibodies. Gastrointestinal transit normalized in a higher proportion of patients with antigliadin IgG and IgA. Anxiety, depression, somatization, and well-being increased in both groups. The presence of antigliadin IgG was associated with overall reductions in symptoms (adjusted odds ratio compared with patients without this antibody, 128.9; 95% CI, 1.16-1427.8; P = .04). Symptoms were reduced even in patients with antigliadin IgG and IgA who reduced gluten intake but were not strictly compliant with the GFD. In controls, a GFD had no effect on gastrointestinal symptoms or gut function.

Conclusions: Antigliadin IgG can be used as a biomarker to identify patients with IBS who might have reductions in symptoms, particularly diarrhea, on a GFD. Larger studies are needed to validate these findings. ClinicalTrials.gov: NCT03492333.