Mapping the Evidence on IgG-Based Elimination Diets for the Management of Irritable Bowel Syndrome in Adults: A Systematic Scoping Review.

Immunoglobulin G (IgG) antibody hypersensitivity is increasingly suggested as a potential trigger of irritable bowel syndrome (IBS) symptoms. Although the underlying mechanism remains unclear, it has been proposed that immunocomplex formation may induce inflammatory responses, exacerbating IBS symptoms. The available evidence on IgG-based elimination diets in adults with IBS was mapped and synthesized in this systematic scoping review, with a focus on gastrointestinal (GI) and extraintestinal symptoms, as well as quality of life (QoL). A systematic search was conducted in 4 databases (PubMed, SCOPUS, Web of Science, and Cochrane Controlled Register of Trials) until the end of January 2025. Three independent reviewers screened titles, abstracts, and full texts. The following data were extracted: study design, participants, IBS subtype, intervention and comparators, outcomes, and results. A qualitative synthesis was performed to summarize study characteristics and reported outcomes. Intervention studies investigating the effects of IgG-based elimination diets in adults diagnosed with IBS (Rome Criteria) in any setting were included. Thirteen studies involving 935 patients with IBS met eligibility criteria. Overall, IgG-based elimination diets were associated with improvements in GI symptoms, including abdominal pain, distention, bowel habits, and stool consistency, as well as QoL. Some studies also noted improvements in extraintestinal symptoms such as anxiety, migraines, and fatigue. There was substantial heterogeneity in study designs, risk of bias, and limitations in blinding and data collection methods. Additionally, concerns were raised regarding the risks associated with excluding multiple foods, which may lead to altered eating habits and increased malnutrition risk. IgG-based elimination diets demonstrate improvements in IBS symptoms and patient QoL. Nonetheless, there are significant methodological limitations in the available evidence, and more well-designed trials are needed to determine the true effectiveness and applicability of these interventions. Systematic Review Registration Open Science Framework (https://doi.org/10.17605/OSF.IO/B52TM).