How the anger melts away with chocolate

Chocolate can help prevent people behaving in a grumpy manner due to a key ingredient that stimulates the release of a "feel-good" chemical, research shows.

Millions of people have long known that snacking on chocolate can work wonders in improving the mood.

A study by Cambridge University has found that the high content of a substance called tryptophan in chocolate is crucial to its ability to make us feel better.

Tryptophan, an amino acid, is used by the body to manufacture the chemical serotonin, which carries messages between brain cells to help regulate emotions.

Serotonin has become known as a "feel-good" chemical because low levels have been linked to bad temper.

The only way to get tryptophan is through diet and some foods are a particularly rich source, notably chocolate and also chicken soup.

In the new study, published in the journal Science by Molly Crockett, Professor Trevor Robbins and colleagues at Cambridge and the University of California, Los Angeles, researchers reduced brain serotonin levels in volunteers for a short time by manipulating their diets.

Role in decision-making

They then compared them with another group of volunteers when playing a game in which one player proposes a way to split a sum of money with a partner.

Those with depleted serotonin levels were far more likely to reject unfair offers.

Miss Crockett, a PhD student, said: "Our results suggest that serotonin plays a critical role in social decision-making by normally keeping aggressive social responses in check.

"Changes in diet and stress cause our serotonin levels to fluctuate naturally, so it's important to understand how this might affect our everyday decision-making."