The research by the University of Warwick's Medical School using data from the Health Survey for England, focused on mental well being and found that high and low mental well being were consistently associated with an individual's fruit and vegetable consumption.

As many as 33.5 percent of respondents with high mental wellbeing ate five or more portions of fruit and vegetables a day, compared with only 6.8 percent who ate less than one portion.

"The data suggest that higher an individual's fruit and vegetable intake the lower the chance of their having low mental wellbeing," Dr Saverio Stranges, the research paper's lead author, said.

As many as 31.4 percent of those with high mental wellbeing ate three-four portions and 28.4 percent ate one-two, researchers said. Other health-related behaviours were found to be associated with mental wellbeing, but along with smoking only fruit and vegetable consumption was consistently associated in both men and women. Alcohol intake and obesity were not associated with high mental wellbeing, researchers said.

"Along with smoking, fruit and vegetable consumption was the health-related behaviour most consistently associated with both low and high mental wellbeing. These novel findings suggest that fruit and vegetable intake may play a potential role as a driver, not just of physical, but also of mental wellbeing in the general population," said Dr Saverio Stranges, the research paper's lead author.

Low mental wellbeing is strongly linked to mental illness and mental health problems, but high mental wellbeing is more than the absence of symptoms or illness; it is a state in which people feel good and function well.

Optimism, happiness, self-esteem, resilience and good relationships with others are all part of this state. Mental wellbeing is important not just to protect people from mental illness but because it protects people against common and serious physical diseases, researchers said.  

"Mental illness is hugely costly to both the individual and society, and mental wellbeing underpins many physical diseases, unhealthy lifestyles and social inequalities in health. It has become very important that we begin to research the factors that enable people to maintain a sense of wellbeing," co-author Professor Sarah Stewart-Brown said.

"Our findings add to the mounting evidence that fruit and vegetable intake could be one such factor and mean that people are likely to be able to enhance their mental wellbeing at the same time as preventing heart disease and cancer," said Stewart-Brown.

The study was published in the BMJ Open.

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