For every additional daily serving of fruit, researchers recorded a measurable drop in mental health risks. Following thousands of Australian high school students over four years, a new University of Sydney study published in Child and Adolescent Mental Health has found that eating an extra daily serving of fruit is linked to a lower risk of depression and anxiety symptoms, while sugary drinks increase that risk.
Tracking Teen Mental Health Across Three Australian States
Researchers tracked 6,537 adolescents across 71 secondary schools in New South Wales, Queensland, and Western Australia. The participants, who had an average age of 12.5 years at the start, completed digital questionnaires annually from Grade 7 through Year 10.
By beginning with students who did not already meet screening thresholds for common mental disorders, the research team could examine whether everyday dietary choices preceded the emergence of symptoms during high school. To capture mental health outcomes without relying on clinical diagnoses, the study utilized validated symptom scales.
Fruit Lowers Symptom Risks While Sugary Drinks Raise Them
Average fruit intake across the study period ranged from two to 2.5 servings a day, with a single serving defined as 150 grams, consistent with guidelines from the National Health and Medical Research Council. The findings point to a clear divergence in how different dietary staples affect adolescent well-being. For every additional daily serving of fruit, researchers recorded a measurable drop in mental health risks.
| Dietary Factor | Depression Risk Association | Anxiety Risk Association |
|---|---|---|
| One additional daily serving of fruit | 13 percent lower risk | 7 percent lower risk |
| Sugar-sweetened beverages | Increased risk | Increased risk |
Conversely, higher consumption of sugar-sweetened beverages—including soft drinks, cordials, and sports drinks—was tied to an elevated likelihood of screening positive for both depression and anxiety. While this negative association appeared in both sexes, it was stronger among boys, particularly regarding anxiety symptoms, though the analysis did not establish whether that sex difference was statistically significant. The analysis found no statistically significant association between vegetable intake—measured with one serving equal to 75 grams—and either mental health indicator.
Nutrition and Mental Health Link Remains Unclear
Lead author Dr Lily Davidson is a Postdoctoral Research Associate at the University of Sydney’s Matilda Centre for Research in Mental Health and Substance Use. She noted that high school is a critical developmental window when young people gain independence over their diets just as psychological vulnerabilities tend to surface. One of the big questions in our field is whether poor nutrition comes before mental health problems, or whether young people experiencing poor mental health simply eat differently
, she explained.
We’re not saying eating an apple will prevent depression, or that having a soft drink will cause anxiety – mental health is far more complex than that. But what you eat is one part of a young person’s life that can potentially be changed, which makes these findings important from a prevention angle.
Dr Lily Davidson, Postdoctoral Research Associate at the University of Sydney’s Matilda Centre for Research in Mental Health and Substance Use
While the observational design prevents researchers from establishing direct causation, the study authors suggested that sugary drink consumption might influence mood. Senior study author Associate Professor Katrina Champion is based at the University of Sydney. She emphasized that public health interventions should focus on making nutritious food more accessible and affordable, adding that schools, families, and governments share responsibility in fostering healthy behaviors before symptoms take root. Readers seeking support can contact Lifeline at 131 114 or Kids Helpline at 1800 55 1800 for individuals aged 5 to 25.
