Jeremy Shere

You’ve heard about tryptophan, right? That’s the amino acid in turkey (and also in other kinds of poultry, chocolate, red meat, and lots of other foods) that supposedly makes you sleepy. But that may not be the case. What tryptophan may actually do, though, according to scientists at the University of Oxford, is affect our sense of trust.

The researchers tested the theory by having volunteers play a two-person game that gives each player a choice: make a move that wins money by taking it from the other player, or make a move that results in both players winning money. Because the later move ultimately results in more money for both players, the cooperation strategy is the best move.
And under normal conditions, the players cooperated around 75 percent of the time.

However, when half the players were given a drink that lowered their tryptophan levels (thereby also decreasing their levels of serotonin–a brain chemical linked to depression), those players cooperated much less frequently. Or, in other words, they trusted their partner less.

It’s not clear why this happens. And it’s also probably not the case that the ubiquity of serotonin reuptake inhibitors used to treat depression has made people less trusting overall.

But it could one day lead to therapies to help people who have trouble trusting and connecting with others.

Source: Technology Review