Diet and Gut Inflammation: The Effect of Diet on Inflammatory Markers in Inflammatory Bowel Disease - A Scoping Review

Background & Aims: Inflammatory bowel disease (IBD) is a chronic inflammatory disorder of the gastrointestinal tract. Studies evaluated the effect of several diets on inflammatory markers in IBD patients. Nevertheless, the results have been inconsistent. Therefore, we conducted this review to evaluate the effectiveness of dietary interventions on inflammatory markers in IBD.Methods: A comprehensive electronic literature search strategy using the PubMed, Embase, and Scopus was conducted in March 2023 and evaluated inflammatory markers included C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and fecal calprotectin (FC), as well as disease severity scores. We included full-text articles that met our inclusion and exclusion criteria. To evaluate the included studies, we used the NHLBI quality evaluation tools.Results: A total of 16 studies were included in our qualitative synthesis. Elemental and polymeric diets showed similar efficacy in reducing Crohn's disease activity index (CDAI) and CRP levels. On the other hand, most studies evaluating the effects of omega 3 fatty acids reported no significant improvement. Moreover, protein supplementation was not seen to improve ESR or CRP levels. Except for improvements in FC levels with IgG4-guided exclusion diet in CD patients with elevated CDAI levels, restrictive diets were successful in controlling functional abdominal symptoms but did not appear to have an impact on inflammation in most studies. Furthermore, disease severity scores, CRP, ESR, and FC levels did not significantly change when eating a high-fiber, low-refined-carb, low-fat diet. Conclusions: Diet plays a vital role in managing IBD by impacting the inflammatory response. Among the interventions studied, enteral nutrition showed the most promising results, improving patients' inflammatory status. Restrictive diets effectively managed symptoms and clinical remission but had limited impact on inflammatory markers. Supplementing the diet with fatty acids, omega 3, or proteins did not definitively improve patients' condition or inflammation.