Dietary fiber intake reduces risk of inflammatory bowel disease: result from a meta-analysis

Several epidemiological investigations have been conducted to evaluate the relationship between dietary fiber intake and inflammatory bowel diseases, but the results are inconsistent. This meta-analysis was performed to quantitatively summarize the evidence from observational studies. PubMed, Embase, and Web of Knowledge were searched for relevant articles published up to November 2014. The combined relative risks were calculated with the fixed- or random-effects model. Dose-response relationship was assessed using restricted cubic spline model. We hypothesized that the meta-analysis could yield a summary effect, which would indicate that dietary fiber intake could decrease the risk of ulcerative colitis and Crohn disease (CD). Overall, 8 articles involving 2 cohort studies, 1 nested case-control study, and 5 case-control studies were finally included in this study. The pooled relative risks with 95% confidence intervals of ulcerative colitis and CD for the highest vs lowest categories of dietary fiber intake were 0.80 (0.64-1.00) and 0.44 (0.29-0.69), respectively. A linear dose-response relationship was found between dietary fiber and CD risk, and the risk of CD decreased by 13% (P < .05) for every 10 g/d increment in fiber intake. The results from this meta-analysis indicated that the intake of dietary fiber was significantly associated with a decreased risk of inflammatory bowel disease.