It is already widely acknowledged that regularly consuming fruit and vegetables can reduce the risk of a number of serious illnesses, including cancer. However, a new study suggests that these foods may also increase a person's happiness levels.

According to the findings, eating up to eight portions of fruit and vegetables per day can improve psychological wellbeing.

English and Australian researchers measured the psychological wellbeing of over 12,300 people. All of the participants kept food diaries detailing what they consumed on a daily basis.

The study found that within two years, an improved diet appeared to lead to major psychological benefits. Happiness levels increased for each extra daily portion of fruit and vegetables that were consumed, up to eight portions per day.

These results stood even when other factors were taken into account, such as changes in people's income and life circumstances.

"Eating fruit and vegetables apparently boosts our happiness far more quickly than it improves human health. People's motivation to eat healthy food is weakened by the fact that physical-health benefits, such as protecting against cancer, accrue decades later. However, wellbeing improvements from increased consumption of fruit and vegetables are closer to immediate," commented Prof Andrew Oswald of the University of Warwick in the UK.

The researchers feel that these findings have major implications, particularly in the developed world, where many people consume unhealthy diets. They believe that healthcare professionals could use this information to try to persuade more people to eat fruit and vegetables.

"Perhaps our results will be more effective than traditional messages in convincing people to have a healthy diet. There is a psychological payoff now from fruit and vegetables, not just a lower health risk decades later," said Dr Redzo Mujcic of the University of Queensland in Australia.

Details of these findings are published in the American Journal of Public Health.