Eating to dare - Nutrition impacts human risky decision and related brain function

Macronutrient composition modulates plasma amino acids that are precursors of neurotransmitters and can impact brain function and decisions. Neurotransmitter serotonin has been shown to regulate not only food intake, but also economic decisions. We investigated whether an acute nutrition-manipulation inducing plasma tryptophan fluctuation affects brain function, thereby affecting risky decisions. Breakfasts differing in carbohydrate/protein ratios were offered to test changes in risky decision making while metabolic and neural dynamics were tracked. We identified that a high-carbohydrate/protein meal increased plasma tryptophan which mapped to individual risk propensity changes. Moreover, the meal-driven fluctuation in tryptophan and risk propensity changes were modulated by individual difference in body fat mass. Using fMRI, we further identified activation in the parietal lobule during risk-processing, of which activities 1) were correlated with the risk propensity changes in decision making, 2) were sensitive to the tryptophan fluctuation, and 3) were modulated by individual’s body fat mass. Furthermore, the activity in the parietal lobule positively mediated the tryptophan-fluctuation to risk-propensity-changes relationship. Our results provide evidence for a personalized nutrition-driven modulation on human risky decisions and its metabolic and neural mechanisms. ### Competing Interest Statement The authors have declared no competing interest.