Objective  To explore the causal relationship between dietary factors and the risk of developing irritable bowel syndrome (IBS) through Mendelian randomization analysis.

Methods  In the study, dietary factor-related characteristics from published Genome-Wide Association Study (GWAS) were selected and extracted as instrumental variables, and GWAS data on IBS were obtained from FinnGen Database. A two-sample Mendelian randomization analysis was primarily performed using the inverse variance weighted (IVW) method, and the test of heterogeneity, the test of pleiotropy, and sensitivity analyses were performed to guarantee the stability and reliability of the results.

Results  The results of IVW method showed that an increase in the average weekly beer and cider intake might significantly increase the risk of developing IBS [OR=2.043, 95%CI (1.126, 3.708), P=0.019]. Conversely, an increase in coffee consumption [OR=0.671, 95%CI (0.473, 0.952), P=0.025] and dried fruits intake [OR=0.452, 95%CI (0.293, 0.697), P<0.001] appeared to correlate with a decreased risk of developing IBS, where the results for dried fruit intake showed a similar pattern of results in the weighted median method analysis [OR=0.427, 95%CI(0.231, 0.787), P=0.006].

Conclusion  The findings suggest a causal relationship between the average weekly intake of beer and cider, coffee, dried fruit and the risk of developing IBS. These findings emphasize the importance of making sound dietary choices in the prevention of IBS.

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