A Systematic Review and Meta-Analysis of Diet and Nutrient Intake in Adults with Irritable Bowel Syndrome

Abstract

Background: Numerous individual and environmental factors including diet may play an important role in the pathophysiology of irritable bowel syndrome (IBS). It is unclear to what degree dietary intake is affected in individuals with IBS. We aimed to perform a systematic review and meta-analysis to summarize dietary intake of adults with IBS and to compare dietary intake between adults with IBS and non-IBS controls. Methods: Ovid MEDLINE, Embase, Cochrane, CINAHL, and Scopus were searched through February 2023 for clinical trials and observational studies measuring usual diet in adults with IBS. Pooled weighted averages were estimated for total energy, macronutrient, and micronutrient data. Mean differences (MD) in nutrient intake were estimated for adults with IBS versus non-IBS controls using a random effects model. Heterogeneity was assessed by the inconsistency index (I2). Key results: Sixty-three full-text articles were included in the review of which 29 studies included both IBS and control subjects. Nutrients not meeting the recommended intake level for any dietary reference values in the IBS population were fiber and vitamin D. Meta-regression by female proportion was positively correlated with total fat intake and negatively correlated with carbohydrate intake. Comparisons between participants with IBS and controls showed significantly lower fiber intake in participants with IBS with high heterogeneity (MD: -1.8; 95% CI: -3.0, -0.6; I2 = 85%). Conclusions and inferences: This review suggests that fiber and vitamin D intake is suboptimal in IBS; however, overall dietary intake does not appear to be comprised. Causes and consequences of reduced fiber in IBS deserve further study. Results of this systematic review and meta-analysis suggest that fiber and vitamin D intake is suboptimal in IBS. However, overall intake of other macro- and micronutrients does not appear to be compromised. Causes and consequences of reduced fiber and Vitamin D intake in IBS deserve further study.