RESUMO
Background: Inflammatory bowel disease (IBD) is a chronic recurrent inflammatory disease of gastrointestinal tract including ulcerative colitis (UC) and Crohn's disease (CD). It is unclear whether there is a causal association between unsaturated fatty acids and IBD. Aims: A two⁃sample Mendelian randomization analysis was used to explore the causal association between unsaturated fatty acids and IBD. Methods: The data of the genome⁃wide association study (GWAS) of unsaturated fatty acids and IBD were obtained from web⁃based public databases. Two⁃sample Mendelian randomization analysis was performed by using inverse⁃variance weighted analysis, and weight median estimator and MR⁃Egger regression were conducted to validate the association of the causal effect. The causality of unsaturated fatty acids on the risk of IBD was evaluated by OR and 95% CI. Results: No direct causal association was found between ω⁃6 fatty acids and CD, and a direct causal association was found with UC. Inverse⁃variance weighted analysis showed a 16% increase in the risk of UC for each standard deviation increase in ω⁃6 fatty acid gene levels (OR=1.16, 95% CI: 1.00⁃1.36, P=0.04). However, no causal association was found between ω⁃3 fatty acids, monounsaturated fatty acids and IBD. Conclusions: ω⁃6 fatty acids may be only causally associated with UC, and no causal association is found between ω⁃3 fatty acids, monounsaturated fatty acids and IBD.