There's a legend that turkey causes that overwhelming desire to get prone after feasting on it, because it contains the calming chemical triptophan. Now researchers at Oxford have linked tryptophan to trust. When they lowered the tryptophan levels, subjects were less likely to trust partners in a strategy game. Tryptophan helps make serotonin in the brain. So who knows, gorging on that Turkey could make you more trusting as well as full.