Association Between Dietary Factors and Psoriasis: A Mendelian randomization analysis

Abstract The WHO recognizes psoriatic arthritis (PsA) as a severe non-communicable disease, with Europe having the highest prevalence worldwide, affecting around 6.4 million people. Though dietary factors are closely associated with psoriasis (PsO) in clinical studies, few researchers have explored this link through Mendelian randomization (MR). This investigation analyzes the causal association between psoriasis and dietary factors. This study used MR analysis with publicly available genome-wide association studies to uncover causal relationships. Causal inference and effect estimates were determined using the inverse variance weighted (IVW) method. Additionally, sensitivity analysis included weighted median and MR-Egger methods, with leave-one-out analysis to ensure reliability. It was found that bread intake was associated with increased psoriasis risk (OR: 1.008; 95% CI: 1.003–1.015; p = 0.004), while beef consumption (OR: 0.989; 95% CI: 0.979–0.999; p = 0.043), cooked vegetables (OR: 0.967; 95% CI: 0.936–0.999; p = 0.046), and pork (OR: 0.985; 95% CI: 0.973–0.997; p = 0.016) were protective against psoriasis. No causal link was observed between other dietary factors and psoriasis. Overall, the study found that bread intake increased psoriasis risk, while beef, cooked vegetables, and pork consumption reduced it. Other diets showed no causal association with psoriasis.