Adherence to the ultra-processed dietary pattern and risk of depressive outcomes: findings from the NutriNet Brasil cohort study and an updated systematic review and meta-analysis

Background & aims We aimed to analyze the prospective association between adherence to the ultra-processed dietary pattern and risk of depressive outcomes using original data from the NutriNet Brasil cohort and via a systematic review and meta-analysis of observational studies that have investigated the same association. Methods In our original research analysis, we used data from 15,960 adults (≥18y) participating in the NutriNet Brasil cohort study, free of depression or depressive symptoms during the baseline (77.5% women, 45.8±13.0y). The mean dietary share of ultra-processed foods (%Kcal/d), calculated from two baseline 24-hour dietary recalls, was used to measure the adherence to the ultra-processed dietary pattern. New cases of depressive symptoms were assessed using the Patient Health Questionnaire-9 over the follow-up period (mean: 18.3 months). Cox proportional hazards models were used for the main analyses. In our systematic review and meta-analysis, we incorporated effect estimates from six prospective cohort studies that have examined the same association, including ours. Results In the adjusted model, each 10% increase in the dietary share of ultra-processed foods was associated with a 10% increase in the hazard of incident cases of depressive symptoms (HR:1.10; 95%CI: 1.07-1.14). This association was slightly attenuated in the models including potential mediators. In our meta-analysis of six prospective studies, high versus low exposure to ultra-processed foods was associated with a summary hazard ratio of depressive outcomes of 1.32; 95%CI: 1.19-1.46; I2: 71%. Conclusion A higher adherence to the ultra-processed dietary pattern was associated with a higher risk of developing depressive outcomes in the NutriNet Brasil cohort and in the meta-analysis.