Genetically predicted processed meat, red meat intake, and risk of mental disorders: A multivariable Mendelian randomization analysis.

Background: Previous observational studies have highlighted potential links between the consumption of processed meat and red meat (such as pork, mutton, and beef intake) and the occurrence of mental disorders. However, it is unclear whether a causal association exists. Therefore, we employed the Mendelian randomization (MR) study to investigate the causal effects of genetically predicted processed meat and red meat on mood disorders (MD), anxiety disorders (AD), and major depressive disorder (MDD).

Methods: Genetic instruments for processed and red meat were selected from the Genome-Wide Association Study (GWAS) of the UK Biobank Study. Their associations with MD (42,746 cases 254,976), AD (35,385 cases and 254,976 controls), and MDD (38,225 cases and 299,886 controls) were obtained from the FinnGen Consortium. The inverse variance weighted (IVW) method was the primary method for two-sample MR analysis. Additionally, we employed complementary analysis to assess the robustness of our MR findings (eg, MR Egger and weighted median). We also conducted multiple sensitivity analyses to investigate horizontal pleiotropy and heterogeneity. Moreover, we performed a univariate and multivariable MR (MVMR) study to evaluate these associations.

Results: In our univariate MR analysis, we observed that genetically predicted beef intake was associated with a reduced risk of MD [odds ratio (OR) = 0.403, 95 % confidence interval (CI) = 0.246-0.659; P = 4.428 × 10], AD (OR = 0.443, 95 % CI = 0.267-0.734; P = 1.563 × 10), and MDD (OR = 0.373, 95 % CI = 0.216-0.643; P = 3.878 × 10). After adjusting for processed meat, pork, and mutton intake in the MVMR analysis, the protective association of beef intake against MD and MDD remained. However, there was no substantial evidence indicating a significant causal relationship between processed meat, pork, and mutton intake and the occurrence of mental disorders. Furthermore, our sensitivity analysis revealed no significant evidence of horizontal pleiotropy.

Conclusion: These findings support a causal relationship between genetically predicted beef intake and reducing the risk of MD and MDD.