Numerous studies link neurotransmitter deficiencies to depression, including GABA, norepinephrine, serotonin, and dopamine. Complex interactions between genetics, environment, and nutrition contribute to neuropsychiatric disorders. Nutrients modulate gene expression through diverse interactions, impacting neurogenesis, synapse function, and brain network activity. Understanding these mechanisms offers insights into neurodevelopment and disorders. Neurotransmitter production relies on nutrients from diet, including B vitamins, amino acids, and minerals. The Mediterranean diet, rich in such nutrients, may aid in preventing depression. Conversely, certain dietary components may promote depression. Further quality research, especially randomized trials, is needed for conclusive evidence. Conflicting findings exist for a variety of diets. Varied definitions and measurements complicate assessments. Some studies suggest links between healthy diets and reduced depression, while others find no association. In this chapter, we discuss evidence on dietary associations with depression, which suggests but does not conclusively prove links.