Study finds correlation between diet and mental health

A diet rich in vegetables and fruit is associated with reduced psychological distress, a detailed analysis of health survey data from more than 45,000 Australians has found.
The study by QUT researchers based at Brisbane’s Translational Research Institute (TRI) found that people who consumed less than one serve of vegetables per day had 1.6 times the odds of suffering psychological distress compared with those who consumed five or more serves per day.
Psychological distress is an umbrella term covering depression, anxiety and stress.
Study first author Dr Kerri Gillespie from QUT’s School of Clinical Sciences, found the benefit of vegetable consumption appeared to be greatest in women.
“Women appear to go on benefiting from vegetables in their diet up to five or more serves per day, while for men the benefit appears to peak at around three or four serves per day,” Dr Gillespie said.
The study also found a correlation between fruit consumption and reduced prevalence of psychological distress, but mostly for women and only up to two daily servings.
Study last author Professor Selena Bartlett, from QUT’s School of Clinical Sciences, said the findings were unexpected.
“The findings are extremely significant because it’s an Australian study with a very large sample of more than 45,000 people. It’s very exciting,” Professor Bartlett said.
“Correlation is never causation and we have to be careful about that, but rarely do we think deeply about how diet affects our psychological health, and I think that's the beauty of the study.”
Dr Gillespie conducted a second study of the association of diet with mental health based on an online survey of healthy adults.
“We found an interesting pattern between the consumption of sugary soft drink and the risk of depression,” Dr Gillespie said.
“Having seven or more cups of soft drinks a week increased the odds of depression by almost five times.
“Conversely, there appears to be a relationship between a high fibre diet and slightly lower anxiety.”
Dr Gillespie cautioned that the study was based on a sample of only 129 people but it showed patterns that could be looked for in a larger sample.
Professor Bartlett said Dr Gillespie’s work added to the evidence of a link between diet and mental health.
“Having the curiosity to ask these questions, that’s how these papers happened,” Professor Bartlett said.
“We are not in any way saying eating more vegetables is a cure for mental health but this research supports the existing health messaging recommending diets high in vegetables and low in sugar.
“We hope this work will help the public and improve health and well-being, which is our role here at the Translational Research Institute,” Professor Bartlett said.
The first study, Vegetable and Fruit Consumption and Psychological Distress: Findings from Australian National Health Survey Data, 2011–2018, was published in The International Journal of Environmental Research and Public Health.
The second study, The association of dietary components with depression and anxiety symptoms: findings from a cross-sectional survey, was published in Frontiers in Nutrition.