Relationship between 39 dietary markers of ultra-processed food and incident depression: evidence from the prospective UK Biobank cohort study.

PURPOSE: To evaluate the association between the intake of markers of ultra-processed food (MUPs) and incident depression.

METHODS

This population-based, prospective cohort study included 171,818 participants, who completed at least one Oxford WebQ. Cox proportional hazard regression models for incident depression were applied, incorporating the consumption of ten MUP categories and 39 specific MUPs, assessed as percentage of total food intake (%TFI), using penalised cubic splines. The hazard ratio (HR)-nadir was defined as the lowest HR on the %TFI axis and rescaled to 1.

RESULTS

Across an average follow-up duration of 10.7 years, 5424 cases of incident depression occurred. The MUP categories flavour, colouring agent, and sweetener were positively and dose-dependently (all linear P < 0.0001) associated with depression risk and the following HRs with corresponding 95% confidence intervals (CIs) were observed as compared to the HR-nadir: flavour (40% vs. 5%TFI; HR (CI) 1.46 (1.29-1.64)), colouring agent (20% vs. 3%TFI; 1.49 (1.30-1.70)), and sweetener (20% vs. 0%TFI; 1.45 (1.32-1.58)). Of the remaining seven MUP categories, two (protein source, fibre) showed a significant U-shaped association and five (flavour enhancer, processing aid, modified starch, varieties of sugar, modified oil) no significant association. Major findings remained robust in various sensitivity analyses.

CONCLUSION

The results suggest that only certain MUPs are associated with incident depression. These findings offer an initial framework for identifying MUPs that should be prioritised in interventions targeting ultra-processed food consumption and in future mechanistic research.