Associations between Global Burden of Disease dietary risk factors and elevated depressive symptoms: the NutriNet-Santé prospective cohort study

Background: Evidence links overall dietary patterns to mental health, but studies on specific food groups and nutrients aligned with dietary guidelines are needed to inform population-level mental health preventive strategies. Within the Global burden of disease Lifestyle And mental Disorder (GLAD) Taskforce (DERR1-10.2196/65576), we aimed to determine the associations between dietary exposures and elevated depressive symptoms, including potential sex-specific differences, in the French NutriNet-Santé cohort. Methods: Prospective observational study using NutriNet-Santé cohort data (2011-2022). Dietary intake was assessed at baseline and every six months for two years using non-consecutive 24-hour records, defining the “dietary exposure window”. Exposures included food groups (fruits, vegetables, legumes, whole grains, nuts & seeds, milk, red meat, processed meat, and sweet drinks) and nutrients (fibre, calcium, omega 3, polyunsaturated fatty acids (PUFA), and sodium) as defined by the Global Burden of Disease (GBD), as well as ultra-processed foods (UPFs) using the NOVA classification. Participants with self-reported depression at baseline or during the dietary exposure window were excluded. The Center for Epidemiologic Studies Depression (CES-D) scale was administered every two years, using validated French cutoffs (≥ 17 for men, ≥ 23 for women) to indicate elevated depressive symptoms. Associations were estimated using multivariable Generalized Estimating Equations (GEE) adjusting for confounders. Results: Among 40,658 adults (75.7% women; mean age 46.6 years), 8,739 (21.5%) met criteria for elevated depressive symptoms at least once during a median follow-up of 8.36 years. Overall, higher intakes of fruits (OR _{100g/d increase} =0.968; 95%CI=0.948-0.989), vegetables (OR _100g/d =0.918; 95%CI=0.890-0.946) and fibre (OR _10g/d =0.954; 95%CI=0.930-0.980) were associated with lower odds of developing elevated depressive symptoms, while higher intake of red meat (OR _10g/d =1.009; 95%CI=1.001-1.017), sweet drinks (OR _100g/d =1.046; 95%CI=1.016-1.076), and the dietary share of UPFs (OR _10%g =1.160; 95%CI=1.126-1.196) were associated with increased odds. Most associations remained only among women, in whom processed meat emerged as positively associated (OR _10g/d : 1.014; 95% CI: 1.001–1.028). Conclusions: Fruits, vegetables, and fibre were associated with reduced odds of elevated depressive symptoms, while red meat, processed meat, sweet drinks, and UPFs were associated with increased odds. These results align with official nutritional guidelines in France and in many countries, supporting their promotion to improve population-level mental health.