Association between ultra-processed food consumption and risk of irritable bowel syndrome and functional dyspepsia: a systematic review and meta-analysis of observational studies.

Abstract

<h4>Background</h4>Ultra-processed foods (UPFs) are increasingly prevalent in global diets and have been linked to various adverse health outcomes. However, evidence regarding their association with disorders of gut-brain interaction (DGBI), such as irritable bowel syndrome (IBS) and functional dyspepsia (FD), remains inconsistent.<h4>Objective</h4>To systematically evaluate the association between UPFs consumption and the risk of IBS and FD through a comprehensive meta-analysis of observational studies.<h4>Methods</h4>We conducted a systematic search of PubMed, Embase, Cochrane Library, and Web of Science from inception through December 2025. Observational studies assessing UPFs intake and clinically diagnosed IBS or FD in adults were included. Pooled effect estimates [odds ratios (OR)] were calculated using random-effects models. Heterogeneity was assessed with <i>I</i> ² statistics, and subgroup analyses were performed by exposure type and assessment method.<h4>Results</h4>Ten studies (<i>N</i> = 232,448) were included. High UPFs consumption was significantly associated with higher odds of IBS (OR = 1.32, 95% CI: 1.16-1.49; based on 9 studies) and FD (OR = 1.26, 95% CI: 1.07-1.49; based on 3 studies). However, the FD finding was primarily driven by a single large cohort and lost statistical significance in sensitivity analysis, indicating the need for cautious interpretation. Subgroup analyses revealed the strongest association for carbonated/sugar-sweetened beverages (OR = 1.98, 95% CI: 1.40-2.80). Heterogeneity was substantially reduced in studies using standardized NOVA classifications or quartile-based comparisons (<i>I</i> ² = 0%). Sensitivity analyses supported robustness. The Egger test did not reveal significant funnel plot asymmetry for IBS outcomes (<i>p</i> = 0.153). Given the limited number of included studies (<i>n</i> = 9), this cannot definitively rule out the presence of publication bias.<h4>Conclusion</h4>These findings suggest that reducing UPFs intake may be a promising dietary strategy for IBS prevention and management. For FD, the evidence is preliminary and requires confirmation in larger prospective studies.<h4>Systematic review registration</h4>https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD420251269914, identifier PROSPERO (CRD420251269914).