Can the food a teenager eats today offer clues about their mental health in the years ahead? A growing body of research suggests that diet and emotional well-being may be connected. Now, a three-year study involving more than 6,500 Australian adolescents has identified two dietary habits that stood out: eating more fruit was associated with fewer symptoms of depression and anxiety, while drinking more sugary beverages was linked to a higher risk of both. The study, published in Child and Adolescent Mental Health, followed students from 71 secondary schools across Australia as they progressed through high school. Researchers wanted to understand whether dietary habits could be associated with the later emergence of common mental health symptoms.
The research included 6,537 adolescents, who were approximately 12.6 years old at the beginning of the study. Participants reported their fruit and vegetable intake and consumption of sugar-sweetened beverages, including soft drinks, cordials and sports drinks. They completed surveys annually over three years. They also assessed symptoms of depression and anxiety using validated screening questionnaires. Importantly, adolescents who already met the screening thresholds for these symptoms at the beginning were excluded from the relevant analyses. This allowed the team to investigate whether dietary habits were associated with the emergence of symptoms during the follow-up period.
One of the clearest findings involved fruit consumption. Each additional daily serving of fruit was associated with a 13% lower risk of meeting the depression symptom threshold and a 7% lower risk of meeting the anxiety threshold over the study period. Sugary drinks showed the opposite pattern. Adolescents who consumed more sugar-sweetened beverages had a higher risk of developing elevated symptoms of both depression and anxiety. These associations appeared in both males and females, although the relationship with anxiety was stronger among males. Interestingly, vegetable consumption did not show a statistically significant association with either depression or anxiety after they accounted for other factors. The team considered variables such as age, physical activity, sex and family socioeconomic circumstances when analysing the results. This helped reduce the influence of some potential confounding factors, although it could not eliminate all of them.
Why might diet influence mental health?
They suggest that several biological pathways could help explain the observed relationship. High consumption of sugary beverages may influence inflammation and hormonal activity, including cortisol regulation, which are processes that can affect brain function and mood. Fruit, meanwhile, provides fibre, vitamins, minerals and other compounds involved in normal physiological processes. However, this study did not directly investigate these biological mechanisms, so they remain possible explanations rather than proven causes.
What should we take away? The findings add to evidence that nutrition may be relevant to adolescent mental health, a period when many mental health difficulties first emerge. However, the study was observational and relied on self-reported dietary habits. It cannot establish that eating more fruit prevents depression or that sugary drinks cause anxiety. Other lifestyle, family and environmental factors may also influence both diet and mental well-being. Still, the research highlights an important opportunity: making nutritious food and healthier drinks more accessible to teenagers could support their overall health, including potentially their mental well-being. Understanding the relationship between everyday habits and emotional health may help researchers develop more effective approaches to prevention.
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