Increasing the amount of fruit and vegetables people eat may lower their risk of clinical depression, according to a recent paper from researchers at the University of Warwick.
Other studies have used people’s subjective responses to surveys to discover a link between eating fruit and vegetables with improved well-being. But this study claimed to find objective evidence of the association between fruit and vegetables and psychological health.
Redzo Mujcic, of Warwick Business School, author of the paper alongside Andrew Oswald, of the University of Warwick, said: “This is an interesting finding and makes the case for an empirical link between fruit and vegetables and improved mental well-being more powerful. The effect is not small as well. If people eat around seven or eight portions of fruit and vegetables a day the boost in mental well-being is as strong as divorce pushing people the other way, to a depressed state.”
Authors found being unemployed had a very bad and significant effect on people’s mental health, greatly increasing the risk of depression and anxiety. “But eating seven or eight portions of fruit and vegetables a day can reduce that by half,” according to the study.
“And the effect is a lot quicker than the physical improvements you see from a healthy diet. The mental gains occur within 24 months, whereas physical gains don’t occur until you are in your 60s.
Authors said this is an important preliminary finding as governments and healthcare policymakers are “currently more interested in the determinants of mental ill-health, such as clinical depression and high levels of anxiety, rather than people’s subjective assessment of their well-being as used in previous research.”
Mujcic and Oswald used data from the Household, Income and Labour Dynamics in Australia (HILDA) survey, which has been done annually since 2001.
In that survey respondents were asked if they have been diagnosed with depression or anxiety along with several questions about their diet and lifestyles.
The study used a representative sample of 7,108 respondents who answered they had not been diagnosed with depression or anxiety in 2007, to see if their diet could predict their chance of depression two years later.
The results revealed an inverse relationship between fruit and vegetables and future depression or anxiety—i.e., the more fruit and vegetables people ate the less likely they were to be diagnosed with a mental illness in later periods.
“If people increase their daily intake of fruit and vegetables from zero to eight they are 3.2 percentage points less likely to suffer depression or anxiety in the next two years,” said Mujcic. “That might not sound much in absolute terms but the effect is comparable to parts of major life events like being made unemployed or divorced. We tested for reverse-causality—i.e., whether it might be that depression or anxiety leads to people eating less fruit and vegetables, but we found no strong statistical evidence of this. However, the next natural step is to do a randomized controlled trial to examine the causal relationship between diet and psychological well-being in society.”