Eating at least eight portions of fruits and vegetables every day will keep you more cheerful and optimistic about the future, scientists say.
The researchers analyzed surveys involving 80,000 Britons, which included questions on their diet and general feelings, according the Daily Mail Thursday.
Each person was given a score between 0 and 10 based on their satisfaction with life.
The study found that those who ate around eight portions of fruit and vegetables a day had an average score that was one point higher than people who did not eat any.
The link remained even when people's exercise levels and overall diet - both of which can influence mood - were accounted for.
Although it is not known exactly how fruit and vegetables improve well being, they contain chemicals known as antioxidants, which are thought to reduce stress levels.
Recently studies have found that children who eat more fruit and vegetables are less at risk of depression in later life.
Andrew Oswald, of the Warwick University's Department of Economics, which conducted the research, said: "This study has shown surprising results. We know that fruit and vegetables carry a lot of antioxidants and those protect us against attacks on the body.
"But how that works through into our minds and emotions, researchers have no idea."