New large-scale study confirms key role of fruit and veg in mental health and happiness

SUBSCRIBE to our fortnightly email newsletter to receive more stories like this. Fruit and veg: Feeling happier, less anxious or more sanguine could be as simple as upping your daily consumption of fruit and veg to eight or nine serves a day.

Could eating a bunch of fruit and veg a day save us, not just doctors’ bills but counselling fees and antidepressant pills? According to the findings of a hew large-scale study by researchers at Australia’s University of Queensland (UQ) and England’s University of Warwick, published in the prestigious American Journal of Public Health, the answer is an enthusiastic yes.

The study, conducted by health economics researcher Dr Redzo Mujcic from UQ’s School of Pharmacy in collaboration with the Uni of Warwick's Professor Andrew Oswald from CAGE, drew on survey data from more than 12,000 Australian adults.

The authors found large, positive psychological benefits within two years of transitioning to a diet that’s richer in fruit and veg.

Professor Andrew Oswald said: “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.”

The researchers found that participants felt ‘happiest’ when they were eating a combined eight or nine servings of fruit and vegetables a day – but that most of us fail to do this.

Their analyses also revealed significant gender differences in the impacts of fruit and veg consumption on measures of mental health, wellbeing and happiness: notably, that the ‘wellbeing’ benefits that accrue by eating more fruit and veg, more often, were substantially higher for women than for men.

Another finding of note was that eating more serves of fruit daily had a stronger impact on a person’s overall mental health than did eating more vegetables.

The UQ-Uni of Warwick study

The aim

Dr Mujcic and his team analysed detailed data from the large-scale annual Household, Income, and Labour Dynamics in Australia (HILDA) Survey in a bid to find answers to two broad questions: Are fruit and vegetables good for us? And how much of them should we be eating, how often, for optimal health and wellbeing?

The data

“The data has been collected from the same set of individuals, aged between 15 and 93, over a two-year period, on their dietary and lifestyle choices along with a number of mental and physical health measures,” Dr Mujcic explained. “With this data, we were able to use much richer statistical methods to answer these types of questions.”

The researchers analysed long-term food-and-mood diaries from 12,385 randomly-sampled Australian adults who participated in the HILDA Survey over 2007, 2009, and 2013.

Another part of the study examined information from the 'Go for 2&5' campaign, run in some Australian states to promote the consumption of two portions of fruit and five of vegetables per day.

Key findings

Dr Mujcic and his colleagues found that participants who upped their intake of fresh fruit and vegetables reported measurable, incremental increases in corresponding levels of wellbeing.

This was the case in the short term – and more significantly, perhaps, over the longer term: increased fruit and veg consumption was a good predictor of appreciably higher levels of wellbeing down the track.

Indeed, the researchers concluded that a person who changed his or her diet from including virtually no fruit and veg to eating eight portions of fresh plant produce a day would likely experience an increase in life satisfaction equivalent to that of moving from unemployment to employment – known to be one of the most significant ‘happiness boosters’ found across the wellbeing research literature.

Substantial improvements in psychological wellbeing could be expected to occur within two years, the researchers found.

“The results showed that the optimal consumption bundle is around four serves of fruit and four serves of vegetables a day for most wellbeing measures, [but also] that less than 25 per cent of Australian adults consume this quantity,” Dr Mujcic says.

The findings are in: fresh fruit and veg - ideally, seven to nine serves a day - could help to keep the psychologist away.
The findings are in: fresh fruit and veg - ideally, seven to nine serves a day - could help to keep the psychologist away.
Peter Renshaw, Flickr CC

More fruit and veg key to happiness, finds earlier UK-US study

The UQ-Uni of Warwick study corroborates the findings of an earlier cross-sectional study, ‘Is Psychological Well-being Linked to the Consumption of Fruit and Vegetables?’ conducted by the University of Warwick economics professor Andrew Oswald, Warwick Medical School’s Professor Sarah Stewart Brown, and Professor David Blanchflower from the USA’s Dartmouth College

That study analysed cross-sectional data from three large-scale, longitudinal British health-and-wellbeing surveys of people randomly selected from Welsh, Scottish and English populations, with respondents from all three totalling around 80,000).

It found positive, incremental linear correlations between greater daily fresh fruit and veg consumption and higher self-reported happiness and wellbeing levels across several reputable measures of psychological wellbeing (life satisfaction; WEMWBS mental wellbeing; GHQ mental disorders; and self-reported health, happiness, nervousness and ‘feeling low’) – associations that persisted even after potential confounding factors had been accounted for.

In simple terms, that means a person’s happiness and mental health rises in “an approximately dose-response way” with the number of daily portions of fruit and vegetables he or she consumes, peaking at around seven portions a day; and that this pattern “is remarkably robust to adjustment for a large number of other demographic, social and economic variables”.

Like Dr Mujcic, the Uni of Warwick-Uni of Dartmouth researchers found that across all three survey populations, fruit and veg consumption’s positive effects on happiness and other measures of wellbeing and calm continued to increase up to at least five and, in most cases, up to seven or eight portions daily, and that these positive psychological effects occurred in both the short and the long term.

While their findings strongly suggested that eating more fresh fruit and veg, more regularly, improves psychological as well as physical health, the researchers concluded that further analyses of longitudinal health and wellbeing data – preferably with large, randomised samples and more comprehensive information on diet – were needed.

The UQ-Uni of Warwick research is such a study. It is one of the first major scientific attempts to explore the impact on people’s psychological wellbeing of eating fresh fruit and veg routinely, and its findings bring us several steps closer to proving scientifically that what we eat does affect how we feel – for better and worse.

What next?

Dr Mujcic says further analyses, using data from large-scale randomised control trials, are needed to better inform existing public health messages and social policy.

Eventually, he conjectures, it may also be possible to link the findings of his study to current research into antioxidants that suggests a connection between optimism and carotenoid levels in the blood; however, further research would be needed in this area.

Public health and social policy implications

The findings of the UQ-Uni of Warwick study challenge the existing ‘healthy-eating’ guidelines provided by governments across the world, Dr Mujcic contends.

“The results showed that the optimal consumption bundle is around four serves of fruit and four serves of vegetables a day for most wellbeing measures, and that less than 25 per cent of Australian adults consume this quantity,” he explains.

“Many public health messages, such as the World Health Organization guidelines, promote the consumption of five serves of fruit and vegetables daily. While the combined portion of eight or more may seem relatively high, the present findings are closely in line with recent studies from the UK and New Zealand,” he says.

“Our research indicates that current guidelines are in need of review.”

Ausveg’s Shaun Lindhe hopes the study will prompt public-health communicators to develop more effective motivational campaigns.

“Previous research has found that the long-term physical benefits of eating fresh vegetables aren’t necessarily enough to motivate consumers to increase their consumption, even when these benefits are widely known and understood,” he says.

“Hopefully, the industry will be able to use these findings to communicate the full range of benefits that vegetables can offer consumers, from physical health to mental health.”

What you can do, now

Following – and if possible, exceeding – the Australian Government’s ‘5+2 a day’ recommendation won’t just lessen your risk of succumbing to chronic-term lifestyle-related disease down the track, it’s a way to make you feel a greater sense of calmer, happiness and overall psychological wellbeing, now and forever.

Enhanced wellbeing is just one more reason to load your shopping basket with the good stuff, fresh from the ground and in all its multi-hued, vitamin- and fibre-rich, phytochemical-packed variety.

And with Australia’s veritable glut of fine fresh produce, there’s really no excuse not to be eating more of it.

“Australians are extremely lucky to have access to the delicious, high-quality fresh vegetables produced by local Australian growers,” Lindhe noted.

“With all these benefits on offer, we encourage consumers to take advantage of the great produce growing right in their back yard.”

Further information

Read the published paper: Mujcic, R and Oswald, A. ‘Evolution of well-being and happiness after increases in the consumption of fruit and vegetables’. American Journal of Public Health, August 2016, Vol. 106, No. 8, pp. 1504-1510. doi: 10.2105/AJPH.2016.303260 

Or download it from Professor Andrew Oswald’s website

For more information on fruit and veg consumption and mental health and wellbeing, check out these earlier, related papers:

Is Psychological Well-being Linked to the Consumption of Fruit and Vegetables?’ by David G. Blanchflower (Bruce V. Rauner Professor of Economics, Dartmouth College, USA), Andrew J. Oswald (Professor of Economics, University of Warwick, CAGE UK and IZA Germany) and Sarah Stewart-Brown (Professor of Public Health at Warwick Medical School), October 2012. 

Major health-related behaviours and mental well-being in the general population: the Health Survey for England’ in the British Medical Journal (BMJ). 

To contact Dr Stranges or Professor Stewart-Brown, email Kelly Parkes-Harrison, Senior Press and Communications Manager, University of Warwick, on k.e.parkes@warwick.ac.uk

SUBSCRIBE to our fortnightly email newsletter to receive more stories like this.

Comments