Editorial: The role of nutrition in mitigating depression: mechanisms, interventions, and outcomes

The intricate relationship between diet and mental health has gained substantial scientific attention over the past decade, with particular focus on how nutritional factors may influence the onset, course, and severity of depressive symptoms. Recent evidence, including a systematic review demonstrating a nonlinear dose-response relationship between the Dietary Inflammatory Index (DII) and depression risk (1), reinforces the role of diet as a key determinant of mental health.The Research Topic "The Role of Nutrition in Mitigating Depression: Mechanisms, Interventions, and Outcomes" brings together six contributions-original research and review papers-that collectively advance our understanding of how dietary patterns, inflammation, metabolic dysregulation, and the gut microbiome converge in shaping depression risk and resilience. This Editorial aims to synthesize these findings, highlight their complementarity, and outline future directions for research in nutritional psychiatry.A cornerstone of this Research Topic is the review Gut microbiota, nutrients, and depression (2), which synthesizes current insights into the bidirectional communication along the gutbrain axis. The authors emphasize how fermentable fibers, polyphenols, fatty acids, and micronutrients modulate microbial diversity, short-chain fatty acid production, and neuroactive metabolite signaling. These mechanisms influence neuroinflammation, neurotransmission, and stress-response circuits, reinforcing the notion that diet is a modifiable biological regulator of mental health.In parallel, the original study Association between the dietary inflammatory index and depressive symptoms in adults with cardiovascular-kidney-metabolic syndrome (3) provides population-level evidence linking higher DII scores to increased depressive symptoms, with metabolic syndrome acting as a partial mediator. These results align with those of Yu et al. (1), who identified a nonlinear association between inflammatory dietary potential and depression.Additional contributions expand this landscape, examining nutrient status, overall dietary quality, lifestyle behaviors, and nutrition-related health outcomes. These include studies on plant-based diets and sleep as mediators of depression in older adults with heart disease (4), vitamin deficiencies as contributors to late-life depression (5), the relationship between food preferences and depressive symptoms among undergraduate medical students (6), and the association between vitamin D deficiency and major depression in individuals with chronic kidney disease (7).Despite their methodological diversity, these studies collectively demonstrate that nutrition influences depression through a constellation of interconnected systems-metabolic, inflammatory, microbial, endocrine, and behavioral.Across studies, dietary patterns modulate multiple biological systems simultaneously. Antiinflammatory, fiber-rich, and nutrient-dense diets support metabolic health, reduce systemic inflammation, and promote favorable gut microbial profiles-mechanisms consistently supported across the Research Topic (1-7).Associations between nutrition and depression emerge more strongly in individuals with cardiometabolic comorbidities, chronic inflammation, or renal impairment. Evidence from Tian et al. (3), as well as findings related to micronutrient deficiencies (5) and vitamin D status (7), highlights the importance of personalized nutrition strategies.Across contributions, benefits derive from overall dietary quality rather than rigid dietary prescriptions. Whole-food diets rich in fiber, antioxidants, and anti-inflammatory components consistently demonstrate protective associations, while highly processed, pro-inflammatory foods are associated with increased depression risk (1-6).This body of evidence underscores the importance of integrating nutritional strategies into mental health prevention and treatment. Policy actions to improve access to healthy foods, reduce dietary inequalities, and enhance food environments could meaningfully reduce population-level depression risk.Despite substantial progress, important gaps remain. Most included studies are observational, limiting causal inference. Heterogeneity in dietary assessment tools, inflammatory indices, and depression measures complicates interpretation. Future research priorities include:• longitudinal and interventional studies, including well-powered randomized controlled trials; • integration of multimodal biomarkers (metagenomics, inflammatory markers, metabolomics, neuroimaging); • precision-nutrition approaches informed by metabolic, microbial, and sociodemographic features; • explicit consideration of social determinants such as food affordability, cultural dietary practices, and socioeconomic inequalities.Together, the contributions in this Research Topic-and complementary meta-analytic findings (1)-emphasize that nutrition represents a powerful, modifiable determinant of depression risk and symptom trajectory. Dietary patterns interact with metabolic health, inflammatory pathways, and the gut microbiome to shape mental well-being.This integrated perspective informs clinical practice, public health policy, and future research priorities. We hope this Research Topic will stimulate further multidisciplinary collaboration and inspire innovative nutrition-based approaches to promoting mental health worldwide.