The administration of the amino acid tryptophan (TRP), contained in food such as fish, soy, eggs, and spinach, promotes interpersonal trust. This is the outcome of a study that we published in Psychological Science.
Interpersonal trust was assessed by the trust game, a task widely used in behavioral economics. This task measures the extent to which a participant (the trustor) trusts the trustee as reflected in money units transferred from trustor to trustee. Participants transferred significantly more money to the trustee after the intake of TRP than after the intake of a neutral placebo. The results support the idea that “we are what we eat”: the food one eats has a bearing on one’s state of mind. Food may thus act as a cognitive enhancer that modulates the way one thinks and perceives the physical and social world. In particular, the supplementation of TRP, or TRP-containing diets, may promote interpersonal trust in inexpensive, efficient, and healthy ways.
Colzato, L.S., Steenbergen, L., de Kwaadsteniet, E.W., Sellaro, R., Liepelt, R., & Hommel, B. (2013). Tryptophan promotes interpersonal trust. Psychological Science. DOI: 10.1177/0956797613500795