Associations between dietary habits and depressive disorder: A diet-wide Mendelian randomization study

Dietary habits are associated with the onset and progression of major depressive disorder (MDD). Nevertheless, a direct association between diet and MDD remains unclear. Therefore, we used a two-sample Mendelian randomization (MR) method to systematically investigate causal relationships between dietary habits and MDD. We collected summary statistics for dietary habits based on publicly available genome-wide association data from the UK Biobank (n = 461,981) and summary statistics of data from the Psychiatric Genomics Consortium (n = 484,598). MR estimates from the genetic tools were combined using a weighted median method. To validate the robustness of the results, we compared the results of the weighted median with those of the inverse variance weighting, weighted mode, and MR-PRESSO. The results MDD was associated with 5 types of dietary habits, including salt added to food (odds ratio (OR): 1.0182, 95% confidence interval (CI): 0.0087-0.0273, P = .0001), beef intake (OR: 0.9395, 95% CI: -0.0964 to -0.0284, P = .0003), oily fish intake (OR: 1.0592, 95% CI: 0.0084-0.1065, P = .0252), bread intake (OR: 0.9313, 95% CI: -0.1366 to -0.0057, P = .0420), and alcohol intake frequency (OR: 1.0085, 95% CI: 0.0006-0.0163, P = .0341). The results suggest a causal relationship between dietary habits and MDD, identifying potential protective and risk factors. These results provide a new reference for the prevention of MDD via dietary regulation.