A compound found in eggs makes people much more generous, new research suggests.

最新研究表明，鸡蛋中含有的化合物可以让人变得更慷慨。

Scientists say that tryptophan, an amino acid found in some foods, can change our behavior.

In experiments they found that consuming a small portion of tryptophan - the equivalent of that found in three eggs - doubled the sum volunteers gave to charity.

Eggs and other foods such as fish and milk are rich in tryptophan, an amino acid that is converted in the body into the feel-good chemical serotonin.

The substance is also marketed as a food supplement called TRP.

Psychologists from Leiden University in the Netherlands, writing in the Frontiers in Psychology journal, said: 'For the first time, we investigated whether the administration of a compound contained in food such as fish, eggs, soy, and milk can promote charitable donating. 'Our study is the first demonstration that charitable donating can be enhanced by serotonin-related food supplements.'

The authors carried out an experiment on 32 men and women, in which half were given a powder containing 0.8 grams of TRP, and the others were given a harmless placebo powder.

Each participant was given £7.50 ($11.25) for taking part in the research and asked whether they were willing to donate part of their financial reward to charity.

Four boxes for Unicef, Amnesty International, Greenpeace, and World Wildlife Fund were left on a table.

When the psychologists counted the takings, they found that those given the TRP powder donated an average of 75p ($1.15), while those who received the placebo donated half as much.

Just how a food supplement could have such an effect is not clear, but the scientists suggest the involvement of oxytocin, the so-called 'cuddle' hormone produced by women during breastfeeding and lovemaking.

The researchers point to the closeness of the areas of the brain associated with serotonin and oxytocin.

They wrote: 'It may be likely that the willingness to donate money to a charity is modulated by the effect that serotonin exerts on oxytocin levels.'Our results support the materialist approach that "you are what you eat".

'The idea [is] that the food one eats has a bearing on one's state of mind. The food we eat may thus act as a cognitive enhancer that modulates the way we deal with the "social" world.'

Commenting on the research, Dr Adam Perkins, neurobiologist at King's College London, said the study could be useful in prisons to encourage harmony among inmates.

He said: 'These results are interesting because they raise the possibility that dietary supplements containing TRP could be used to assist with boosting charitable attitudes and behavior in the population.'