Protective and pathogenic dietary factors in bronchitis: Insights from Mendelian randomization

Previous studies have suggested a potential association between dietary habits and bronchitis but the exact nature of this relationship remains unclear. This study aims to elucidate the causal relationship between these 2 factors using a Mendelian randomization (MR) approach. We performed a two-sample MR analysis using genome-wide association studies data from the UK Biobank for 231 dietary phenotypes and FinnGen for bronchitis cases. Single nucleotide polymorphisms were selected as IVs after rigorous filtering, including significance thresholds (P < 5e-6), F-statistics (>10), and tests for pleiotropy and reverse causality. The inverse variance weighted method was the primary analytical approach, with MR-Egger, weighted median, and other methods for sensitivity checks. Our MR analysis revealed significant causal effects of dietary phenotypes on bronchitis. Dried fruit intake (odds ratio [OR] = 0.963, 95% confidence intervals [CI]: 0.940-0.986, P = .002), beef intake (OR = 0.954, 95% CI: 0.919-0.991, P = .015), and fresh fruit intake (OR = 0.977, 95% CI: 0.945-0.999, P = .043) exhibited protective effects against bronchitis. Conversely, alcohol intake compared to 10 years prior increased risk (OR = 1.055, 95% CI: 1.001-1.111, P = .042). Sensitivity analyses confirmed robustness. This study utilized publicly available genome-wide association studies data to explore the causal relationships between dietary habits and bronchitis using MR methods. It found dried and fresh fruit, and beef intake protect against bronchitis, while alcohol increases risk. These findings offer insights for future research and potential dietary interventions for bronchitis management.