Causal Relationships Between Popular Diets (Low-Calorie, Vegetarian, and Gluten-Free Diets) and Inflammatory Skin Diseases: A Mendelian Randomization Study.

Background: Inflammatory skin diseases including acne, atopic dermatitis, psoriasis, and psoriatic arthritis, and have become a major global public health concern. Diet's impact on inflammatory skin diseases has attracted significant attention. This study utilised the Mendelian randomization (MR) method to investigate the relationship between popular diets, such as low-calorie, vegetarian, and gluten-free diets, and several common inflammatory skin diseases.

Methods: Our study employed five MR methods, including the inverse variance weighted (IVW), MR-Egger, simple mode, weighted median, and weighted mode. Sensitivity analysis was conducted to confirm the accuracy and reliability of the research findings.

Results: The results revealed a positive causal relationship between low-calorie diets and the risk of psoriatic arthritis (odds ratio [OR]: 1.05; 95% confidence interval [CI]: 1.01-1.10; p = 0.008) but no significant association with other diseases. No significant association was observed between vegetarian or gluten-free diets and the diseases. The reliability of the conclusion was further validated through the MR-Egger regression, MR-PRESSO analysis.

Conclusion: This study offers preliminary insights into the links between diet and inflammatory skin conditions, with future large-scale, multi-method research needed to validate these findings and inform dietary recommendations.