Is there a place for an IgG antibody-based elimination diet in irritable bowel syndrome?

Review by Prof. Edyta Tulewicz-Marti (Poland)

Study Summary 

Up to 90% of IBS patients report symptom exacerbation linked to consumption of specific foods, which may be related to an intolerance to a specific food. Food intolerances often exhibit a dose-dependent pattern, which may offer an opportunity to provide personalized dietary therapies for IBS.¹ For that reason, an immunoglobulin (Ig)G-antibody–based elimination diet could present a potential solution. The study performed by Singh et al. aimed to assess the efficacy of an elimination diet by using a novel IBS-specific IgG assay. It was a randomized, double-blind, sham-controlled trial enrolling subjects with IBS from 8 centers; a total of 238 patients were randomized. Subjects positive for ≥1 food on an 18-food IgG assay and an average daily abdominal pain intensity score between 3.0 and 7.5 on an 11.0-point scale during a 2-week run-in period were randomized to either an experimental antibody-guided diet or a sham diet for 8 weeks. The primary outcome was a ≥30% decrease in abdominal pain intensity for ≥2 of the last 4 weeks of the treatment period. According to the results 223 patients with IBS were included in the modified intention-to-treat analysis. According to data, a significantly greater proportion of subjects in the experimental diet group met the primary outcome than those in the sham diet group (59.6% vs 42.1%, P = .02). Subgroup analysis revealed that a higher proportion of subjects with constipation-predominant IBS and IBS with mixed bowel habits in the experimental diet group met the primary endpoint vs the sham group (67.1% vs 35.8% and 66% vs 29.5%, respectively).²

Commentary 

According to the data from this, the largest study in this field of research, patients on an IgG-guided elimination diet were more likely to achieve the primary endpoint than those on a sham elimination diet. Diving into data, subgroup analysis suggests more robust benefits for subjects with constipation-predominant IBS and IBS with mixed bowel habits compared to IBS-D. As in many prior IBS studies, the placebo-response rate as high, at approximately 40%, thereby limiting interpretation of subgroup analyses. While these data may indicate the effectiveness of a personalized elimination diet based on a novel IBS-specific IgG assay, especially in terms of relief of pain; however, a few limitations need to be noted. First, there was lower adherence to the elimination diet than to the sham diet, and second, some patients discontinued the study. Furthermore, more data are needed on the mechanisms underlying how immunoglobulin G-antibody responses to a food antigen generate symptoms in IBS.

Citation

1. Pasta A, Formisano E, Calabrese F, Plaz Torres MC, Bodini G, Marabotto E, Pisciotta L, Giannini EG, Furnari M. Food Intolerances, Food Allergies and IBS: Lights and Shadows. Nutrients 2024;16:26
2. Singh P, Chey WD, Takakura W, Cash B, Lacy BE, Quigley EMM, Randall CW, Lembo A. A Novel, IBS-Specific IgG ELISA-Based Elimination Diet in Irritable Bowel Syndrome: A Randomized, Sham-Controlled Trial.  Gastroenterology 2025;168:1128-36.

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