The joint associations of physical activity and ultra-processed food consumption with depression: A cohort study in the UK Biobank.

Background: Despite substantial evidence regarding independent associations between physical activity (PA) and ultra-processed foods (UPF) consumption with depression, the joint effects of these two factors remain unknown.

Methods: This study included 99,126 participants without depression in the UK Biobank at baseline. A 24-h recall method was used to assess UPF consumption, and self-reported total physical activity (TPA), moderate-to-vigorous physical activity (MVPA), and vigorous physical activity (VPA) were assessed by metabolic equivalent task (MET). A series of Cox proportional hazard regression models were used to explore the independent and joint effects of TPA, MVPA, VPA and UPF consumption on depression.

Results: The incidence rate of depression was 1.94 % [95 % confidence interval (CI): 1.80 %-2.10 %] per 1000 person-years after an average follow-up of 12.10 years. We found that MVPA and UPF consumption had additive interactions on depression risk (p < 0.05). Participants in Q1 of TPA and Q4 of UPF consumption (HR: 1.83, 95%CI: 1.45-2.31) showed a higher risk for depression than those in Q4 of TPA and Q1 of UPF consumption. Compared with the participants with WHO guideline-recommended MVPA and the lowest UPF consumption, those below recommended MVPA (HR: 1.51, 95%CI: 1.20-1.89) or above recommended MVPA (HR: 1.40, 95%CI: 1.10-1.78) and with the highest UPF consumption had a higher risk for depression.

Limitations: Study limitations include use of self-reported data, observational study and concerns regarding generalizability.

Conclusion: Higher UPF consumption, accompanied by lower PA levels regardless of TPA, MVPA, and VPA, is associated with a higher risk of depression. Our study offers insights on public health priorities to decrease the risk of depression in the population by addressing both PA and UPF consumption together.