Consumption of vegetables and fruit and the risk of inflammatory bowel disease

To date, associations between consumption of vegetables and fruit and the risk of inflammatory bowel disease have been a controversial subject. Therefore, we carried out a meta-analysis to evaluate the associations. A comprehensive search was performed in PubMed, Embase, Web of Science, and the China National Knowledge Infrastructure to identify all relevant studies. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) from random-effects or fixed-effects models were calculated. Publication bias was estimated using Egger's test and the funnel plot. A total of 14 case-control studies were included in this meta-analysis. On the basis of the highest versus the lowest analysis, consumption of vegetables was associated inversely with the risk of ulcerative colitis (UC) (OR=0.71, 95% CI 0.58-0.88, n=9 studies), but not with Crohn's disease (CD) (OR=0.66, 95% CI 0.40-1.09, n=8 studies). Higher consumption of fruit was associated inversely with the risk of UC (OR=0.69, 95% CI 0.49-0.96, n=8 studies) and CD (OR=0.57, 95% CI 0.44-0.74, n=10 studies). For intake of vegetables and the risk of CD, subgroup analysis showed a significant association for studies carried out in Europe (OR=0.36, 95% CI 0.23-0.57), but not in Asia (OR=1.00, 95% CI 0.50-2.03). No significant publication bias was found for the analysis of intake of vegetables and the risk of UC, intake of fruit and the risk of UC, and intake of vegetables and the risk of CD. This meta-analysis indicates that consumption of vegetables and fruit might be associated inversely with the risk of UC and CD, and the results need to be further confirmed.