Objective To investigate the causality between dietary factors and gastroesophageal reflux disease (GERD) based on Mendelian randomization (MR) analysis. Methods Twenty-nine dietary factors were considered as exposure factors, and GERD as the outcome factors. Relevant data were obtained from the IEU open genome-wide association study (GWAS) database, and appropriate instrumental variables (IVs) were selected for MR analysis. The inverse variance weighted (IVW) method was primarily used to evaluate the results, with MR-Egger regression and the weighted median estimator (WME) serving as supplementary MR analysis methods to explore the associations between various dietary factors and GERD. Different models and tests were employed for sensitivity analysis to examine heterogeneity, horizontal pleiotropy, and robustness of the results. Results A total of eight dietary factors were identified to have significant associations with GERD through MR analysis. Specifically, intake of dried fruits (OR=0.530, 95%CI, 0.418 to 0.674, P < 0.001), amount of fresh fruits (OR=0.631, 95%CI, 0.480 to 0.829, P=0.001), intake of herbal tea (OR=0.995, 95%CI, 0.990 to 0.999, P=0.026), intake of oily fish (OR=0.793, 95%CI, 0.643 to 0.976, P=0.029), and intake of cheese (OR=0.718, 95%CI, 0.597 to 0.868, P=0.001) were negatively associated with GERD, while alcohol consumption frequency (OR=1.329, 95%CI, 1.207 to 1.463, P < 0.001), pork intake (OR=1.806, 95%CI, 1.116 to 2.922, P=0.016), and intake of sugary food/beverage (OR=4.062, 95%CI, 1.543 to 10.696, P=0.001) were positively associated with GERD. Conclusion Intake of dried fruits, fresh fruit, herbal tea, oily fish, and cheese may reduce the risk of GERD, while high alcohol consumption frequency, pork intake, and intake of sugary foods or beverages are associated with an increased risk of GERD.