Vegetarian Diet and Possible Mechanisms for Impact on Mood

Several randomized controlled intervention trials have reported improvements in mood following the adoption of vegetarian diets. However, mechanisms contributing to this improvement have not been investigated. Mood is regulated by the action of the neurotransmitters serotonin and norepinephrine and the proinflammatory cytokines (e.g., IL-1β, TNF-α, IL-6, and IL-2) and eicosanoids (e.g., PGE₂). Vegetarian diets are inherently rich in antioxidants, and adherence to vegetarian diets is associated with low oxidative stress and PGE₂ concentrations. Furthermore, the high carbohydrate-to-protein ratio of vegetarian diets should facilitate tryptophan entry into the brain and the production of serotonin. This chapter explores the aspects of vegetarian diets that would theoretically promote healthful mood states by promoting neurotransmitter action.