Effects of gluten on dyspeptic symptoms: a systematic review and meta-analysis of clinical trials

Context Research on the effects of gluten on dyspeptic symptoms has shown conflicting results. Objective The aim of this systematic review and meta-analysis of clinical trials was to assess the effects of gluten on dyspeptic symptoms. Data Sources A systematic search of the PubMed, ISI Web of Science, Scopus, Cochrane, and Embase online databases was performed up to May 2022. Data Extraction Randomized controlled trials (RCTs) and non-RCTs that examined the impact of a gluten-free diet, a low-gluten diet, or a gluten challenge on dyspeptic symptoms, including early satiety, epigastric pain, bloating, and nausea, were selected independently by 2 authors. The GRADE (Grading of Recommendations Assessment, Development, and Evaluation) framework was used to assess the certainty of the evidence. Results were pooled using a random-effects model and expressed as weighted mean differences (WMDs) and 95%CIs. Data Analysis Of the 7641 citations retrieved, 27 articles (18 RCTs and 9 non-RCTs) were included in the systematic review. Of those, 5 RCTs were eligible for the meta-analysis. The pooled results indicated that gluten challenge significantly increased the severity of bloating (WMD = 0.67; 95%CI, 0.37-0.97; I-2 = 81.8%; n = 6), early satiety (WMD = 0.91; 95%CI, 0.58-1.23; I-2 = 27.2%; n = 5), and epigastric pain (WMD = 0.46; 95%CI, 0.17-0.75; I-2 = 65.8%; n = 6). However, the effect of gluten challenge on the severity of nausea (WMD = 0.13; 95%CI, -0.17 to 0.43; I-2 = 0.0%, n = 5) was nonsignificant. Conclusion Gluten challenge significantly worsened dyspeptic symptoms, including bloating, early satiety, and epigastric pain, but did not affect nausea. These findings suggest that gluten restriction could be efficient in reducing dyspeptic symptoms. Well-designed large RCTs recruiting homogenous groups of patients with functional dyspepsia are needed to clarify the effectiveness of gluten restriction on dyspeptic symptoms.