Anti-inflammatory diets and mental health: a scoping review of randomized controlled trials and systematic evidence syntheses

Background Inflammation has been proposed as a biological pathway linking diet to mental health. Anti-inflammatory dietary patterns, including the Mediterranean and DASH diets, may reduce systemic inflammation and thereby influence mental health outcomes. However, evidence across study designs has not been comprehensively synthesized. Objective This scoping review aimed to identify randomized controlled trials (RCTs) and systematic evidence syntheses to summarize the effects of anti-inflammatory dietary interventions or patterns on mental health outcomes in adults. Methods Searches were conducted in scientific databases through February 2025. Eligible RCTs included adult participants receiving an anti-inflammatory dietary intervention with reported mental health outcomes. Eligible systematic evidence syntheses included systematic reviews with or without meta-analysis, scoping reviews, and umbrella reviews examining associations between anti-inflammatory diets and mental health. Article screening and review were conducted in duplicate, and data extraction followed standardized procedures appropriate for each study type. Results A total of 21,923 records were identified, of which 42 RCTs and 23 systematic evidence syntheses met the inclusion criteria. Of the 42 RCTs, 28 reported significantly greater improvements in at least one mental health outcome compared with controls following an anti-inflammatory dietary intervention. Most trials evaluated Mediterranean diet-based interventions. Across RCTs, improvements were most consistently observed for depressive symptoms, while findings for anxiety, mood, stress, and quality of life were mixed. Across the 23 systematic evidence syntheses, findings for depression outcomes were generally positive, with multiple reviews reporting inverse associations between adherence to anti-inflammatory dietary patterns and depression risk or symptom severity. Evidence for anxiety outcomes across reviews was more heterogeneous and less consistent. Conclusion Anti-inflammatory dietary patterns, particularly the Mediterranean diet, are associated with improvements in depressive symptoms across randomized controlled trials and systematic evidence syntheses, with less consistent findings for anxiety and other mental health outcomes. Benefits were most consistently observed among individuals with existing mental health symptoms. Interpretation is limited by heterogeneity in dietary interventions, multimodal study designs, populations, and outcome measures. Future research using standardized dietary protocols, longer follow-up periods, and biomarker assessment is needed to strengthen causal inference and clarify underlying mechanisms.