Mediterranean-style dietary components and self-reported depression: a cross-sectional analysis of 502,359 UK adults in the UK Biobank cohort

Background: Mediterranean-style diet adherence has been associated with lower depression prevalence, but studies are typically small and adjust for few confounders. We aimed to estimate cross-sectional associations between individual Mediterranean-style dietary components and reported depression, and how far they attenuate with broader sociodemographic and lifestyle adjustment.Methods: Cross-sectional analysis of the UK Biobank cohort (N=502,359). Six self-reported dietary variables - oily fish, non-oily fish, fresh fruit, salad and raw vegetables, cooked vegetables and processed meat - were tested against self-reported depression using binary logistic regression, modelled individually with progressive adjustment (full adjustment: age, sex, smoking, medication, Townsend deprivation index, month of assessment, educational attainment), then all together in one multivariable model.Results: 28,194 participants (5.6%) reported depression. Fully adjusted, higher intakes of oily fish (odds ratio[OR]=0.900, 95% CI [confidence intervals] 0.888 to 0.912), non-oily fish (OR=0.931, 0.917 to 0.945), fresh fruit (OR=0.974, 0.966 to 0.982), salad and raw vegetables (OR=0.970, 0.964 to 0.976) and cooked vegetables (OR=0.967, 0.960 to 0.974) were each associated with lower odds. Conclusion: Individual components of a Mediterranean-style diet showed small, consistent associations with lower odds of self-reported depression, not explained by the measured confounders. The design does not support causal interpretation. For researchers, prospective designs with repeated dietary measurement and diagnosed outcomes are needed; for practitioners and policymakers, these estimates do not support dietary components as a substitute for established treatment or as a stand-alone prevention target.