Causal relationship between dietary habits and Alzheimer's disease risk: a univariable and multivariable Mendelian randomization study

Background: The objective of this study was to evaluate the causal link between dietary habits and Alzheimer's disease (AD), utilizing a two-sample Mendelian randomization approach. Methods: In this research, we utilized two-sample Mendelian randomization (MR) analyses in tandem with genome-wide association study (GWAS) data to comprehensively assess the causal link between 17 dietary habits and the risk of AD. To ensure the robustness of the findings, both univariate Mendelian randomization (UVMR) and multivariate Mendelian randomization (MVMR) methods were utilized. All analyses were conducted using inverse variance weighting (IVW) methods, while sensitivity analyses were carried out utilizing the maximum likelihood, MR-RAPS, and MR-Egger methods. Results: In the UVMR analysis, a significant association was observed between the intake of processed meat (OR = 1.26, 95% CI: 1.01-1.59, P = 0.044), poultry (OR = 2.06, 95% CI: 1.18-3.59, P = 0.011), and beef (OR = 1.79, 95% CI: 1.25-2.57, P = 0.002) and an increased risk of AD. Sensitivity analyses revealed that processed meat, poultry, and beef intake consistently exhibited positive associations under various methods. In MVMR analyses, after depression was adjusted, positive associations were found for processed meat intake (OR = 1.376, 95% CI: 1.015-1.864, P = 0.040), poultry intake (OR = 2.174, 95% CI: 1.205-3.922, P = 0.010) and beef intake (OR = 1.428, 95% CI: 0.866-2.355, P = 0.163), which showed significant positive associations or a positive trend. Conclusion: The present research revealed substantial correlations between the consumption of processed meat, poultry, and beef and the risk of AD. This was determined through a comprehensive two-sample Mendelian randomization analysis.