Understanding nutrition beyond calories and vitamins: Why plants are beneficial

The relationship between nutrition and mental health has been an emerging area of research in nutritional psychiatry over the past decade. Understanding the complex interplay between dietary factors and mental health is of paramount importance from a public health perspective. It is widely accepted that dietary patterns abundant in unprocessed plant foods are associated with improved mood and a decreased risk of mental health disorders such as depression. This chapter discusses potential pathways and mechanisms of action ranging from neuroinflammation to the gut–microbiome axis. A particular emphasis is placed on antioxidants and oxidative waste, polyphenol compounds such as quercetin and their monoamine oxidase (MAO)-inhibitory properties, saturated and polyunsaturated fatty acids, magnesium intake, tryptophan metabolism, and brain-derived neurotrophic factor. The chapter concludes with a discussion of the role of plant foods in whole-of-diet patterns, diet quality, and mood disorders.