Pre-Illness Index-Based Dietary Patterns and Inflammatory Bowel Disease Risk: A Systematic Review and Meta-Analysis.

Diet is a modifiable environmental factor believed to play an essential role in the occurrence of inflammatory bowel disease (IBD). Dietary patterns could better reflect the effects of interaction of the various dietary components. This study aimed to assess the impact of pre-illness index-based dietary patterns on IBD risk. A comprehensive search was conducted in 4 medical databases (PubMed, Web of Science, Embase, and Cochrane Library). A random-effects model was employed to calculate the pooled relative risk (RR) and 95% CIs. Subgroup analysis was conducted according to the study design, region, age group, regression model used, and version of the dietary index. Statistical significance was defined as a 2-sided P value of <.05. A total of 14 studies were finally included. The meta-analysis revealed that adhering to a Mediterranean dietary pattern was associated with a lower overall risk of IBD (RR 0.66, 95% CI 0.47-0.93). Similarly, higher adherence to the "healthy dietary pattern" significantly reduced the risk of IBD (RR 0.81, 95% CI 0.71-0.92). Conversely, a diet with a higher inflammatory potential was linked to an increased risk of Crohn's disease (RR 1.44, 95% CI 1.14-1.82). Subgroup analysis suggested that the Mediterranean dietary pattern was not significantly associated with IBD risk among the adult population, and that diets with a high inflammatory potential increased the risk of ulcerative colitis in Asian studies (RR 2.06, 95% CI 1.07-3.96). Pre-illness dietary patterns have a significant influence on IBD development. This meta-analysis found that dietary patterns such as the Mediterranean dietary pattern and the healthy dietary pattern reduce IBD risk in the general population, while pro-inflammatory diets increase it. Moreover, regional and other factors such as age group may further modulate these associations. PROSPERO registration No. CRD42023474588.