Prospective associations between dietary risk factors and depressive symptoms: results from the NutriNet-Brasil cohort

Background: Depressive disorders affect over 280 million people worldwide and are a leading cause of disability. The Global Burden of Disease study identified key dietary exposures linked to health outcomes, but dietary exposures are not yet linked to mental disorders in the Global Burden of Disease, which led to the establishment of the Global burden of disease Lifestyle And Mental Disorder Taskforce to investigate diet–mental health associations, including the role of ultra-processed foods Aim: To assess the prospective associations between dietary exposures and the incidence of depressive symptoms among Brazilian adults participating in the NutriNet Brasil Cohort Methods: Data from 18,033 adults free of depression at baseline were analyzed. Dietary intake was assessed using two web-based 24-hour recalls (Nova24h). Exposures included food groups and nutrients defined by the GLAD project. Incident depressive symptoms were identified using the PHQ-9 scale (score ≥9) during a 31-month follow-up. Cox proportional hazard models were applied, and the models were adjusted for potential confounders. Results: During follow-up, 3,590 participants developed depressive symptoms. Higher intakes of fruits, vegetables, legumes, whole grains, nuts and seeds, unprocessed/minimally processed whole plant foods, fiber, and calcium were inversely associated with depressive symptoms (varying from 4% to 8% lower risk). Conversely, higher consumption of processed meats, sugar-sweetened beverages, ultra-processed foods, sodium, and trans fatty acids was associated with an increased risk (varying from 6% to 21% higher risk). Results were consistent across sensitivity analyses. Conclusions: Healthy dietary patterns rich in unprocessed and minimally processed foods and low in ultra-processed products were associated with a lower risk of depressive symptoms. Findings reinforce diet as a modifiable determinant of mental health and support policies promoting unprocessed and minimally processed foods and regulating ultra-processed products.