Background: The importance of foods or food constituents in mental health is increasingly recognized, and "nutritional psychiatry" is a growing discipline. Objective: This narrative review aims to present work supporting associations between food or food constituents and mental health, specifically depressive disorders. Methods: The data presented is derived from preclinical and clinical work, including in vitro and in vivo assays, as well as observational studies and randomized clinical trials of dietary interventions. The focus of the review is the mediation of inflammatory processes and oxidative stress by dietary constituents that are an integral part of a healthy diet, such as the Mediterranean diet and similar. Results and Discussion: We present evidence for the role of the diet in prevention and management of depressive disorders, beyond the effect of individual nutrients. The findings indicate that among the dietary components with higher degree of evidence to influence depressive disorders are long chain n-3 polyunsaturated fatty acids (EPA and DHA), and various dietary bioactive compounds, especially plant-derived secondary metabolites represented by polyphenols such as flavonoids and resveratrol. Conclusion: Diet exerts an important role on mental health, and evidence indicates that some dietary constituents contribute to the prevention of depressive disorders.