Antigliadin IgG spots IBS patients who benefit from gluten-free diet

Some patients with irritable bowel syndrome (IBS) may achieve symptom reduction, particularly diarrhoea, on a gluten-free diet (GFD), and who these patients are may be identified by using the antigliadin immunoglobulin G (IgG) as a biomarker, according to a study.

The study included 50 IBS patients (ROME III, all subtypes) with or without serologic reactivity to gluten (antigliadin IgG and IgA) and 25 healthy individuals (controls) who took part in a 4-week diet that excluded foods containing gluten.

Researchers assessed gastrointestinal transit, gut symptoms, anxiety, depression, somatization, dietary habits, and microbiota composition before and after the dietary intervention. They also determined the HLA-DQ2/DQ8 status of the participants. GFD compliance was assessed by measuring gluten peptides in stool.

While there was no difference in symptoms in the IBS group at baseline, patients with antigliadin IgG and IgA reported significantly less diarrhoea than those without these antibodies following a 4-week GFD (p=0.03). IBS symptoms improved in 18 of 24 patients (75 percent) with antigliadin IgG and IgA and in 8 of 21 patients (38 percent) without the antibodies.

GFD led to reductions in symptoms including constipation, diarrhoea, and abdominal pain for patients with antigliadin IgG and IgA, whereas it only eased pain for patients without the antibodies. Moreover, more patients who had the antibodies achieved gastrointestinal transit normalization.

In multivariable regression models, the presence of antigliadin IgG correlated with overall reductions in symptoms (adjusted odds ratio, 128.9, 95 percent CI, 1.16–1427.8; p=0.04). Even patients with antigliadin IgG and IgA who reduced gluten intake but were not strictly compliant with the GFD experienced symptom reductions.

Meanwhile, in the control group, the GFD had a null effect on gastrointestinal symptoms and gut function.