The relationship between processed meat, red meat, and risk of cardiovascular disease and type 2 diabetes: A Mendelian randomization study

Numerous observational studies have indicated a potential association between the consumption of processed and red meat and an increased risk of cardiovascular disease and type 2 diabetes mellitus (T2DM). However, the presence of a causal relationship remains uncertain. Therefore, the purpose of this study is to evaluate the impact of processed meat and red meat (pork, lamb, and beef) on the risk of cardiovascular disease, including coronary artery disease (CAD), hypertension, and stroke, and T2DM, using a Two-Sample Mendelian randomization (MR) analysis. MR analysis was conducted using the inverse-variance weighted (IVW), weighted median (WM), and MR Egger methods. To identify heterogeneity and pleiotropy, Cochrane's Q test and MR-Egger test were employed. Additionally, the stability of the MR results was assessed using the leave-one-out method. IVW analyses reveal no causal association between the consumption of processed and red meat and the incidence of CAD, hypertension, stroke, and T2DM (P > 0.05). When considering processed meat intake, heterogeneity is observed in hypertension and stroke outcomes (P < 0.05). For pork intake, heterogeneity is seen in hypertension, stroke, and T2DM (P < 0.05). Lamb intake shows heterogeneity in hypertension and T2DM (P < 0.05). However, other exposures and outcomes examined show no heterogeneity (P > 0.05). No significant pleiotropy is detected for all exposures through an MR-Egger test (P > 0.05). Furthermore, the Leave-one-out test demonstrates the robustness of the results. The study discerned no observable impact of red and processed meat consumption on CAD, hypertension, stroke, and T2DM. The findings of this study challenge the prevailing conventional perspective in the field.