Causal relationship between dietary factors and oral mucosal lesions: Two-sample Mendelian randomization analysis

Previous studies have suggested potential associations between some dietary factors and oral mucosal lesions (OMLs), however, existing research could be biased due to limited sample size and unaccounted confounding factors. This study aimed to explore the causal relationships between 13 common dietary factors and 3 OMLs using 2-sample Mendelian randomization (MR) analysis. Data for the MR analysis were extracted from publicly available genome-wide association study statistics. Thirteen dietary intakes were selected as exposure factors, recurrent aphthous stomatitis (RAS), oral lichen planus (OLP), and oral leukoplakia (OLK) were examined as outcomes. Summary data associated with the exposures and outcomes were obtained from individuals of European ancestry. The primary analysis of exposures and outcomes was conducted using the inverse variance weighted (IVW) method. Furthermore, the MR-Egger, weighted median, simple mode, and weighted mode were used to validate the final results. To assess the assumptions, sensitivity tests including the MR-Egger intercept test, leave-one-out analysis, funnel plot, scatter plot, and MR-PRESSO were carried out. The false discovery rate (FDR) correction was employed to adjust P-values (P-FDR) for multiple hypothesis testing. After FDR correction, the analysis revealed a significant causal relationship between dried fruit intake and RAS risk (OR = 0.281, 95% CI = 0.133-0.590, P-FDR = .004), and between nonoily fish intake (OR = 0.072, 95% CI = 0.011-0.453, P-FDR = .026) and OLP risk. No horizontal pleiotropy or heterogeneity was detected. This study suggests that dried fruit intake and nonoily intake may lower the risk of RAS and OLP, respectively. These findings provide more favorable evidence for dietary recommendations for OMLs.