Eating more fruit and drinking fewer sugar-sweetened beverages may significantly reduce the risk of depression and anxiety in teenagers, according to Gram Research analysis of a three-year study of 6,537 Australian adolescents. Each additional daily fruit serving reduced depression risk by 13% and anxiety risk by 7%, while higher sugar-sweetened beverage intake increased depression risk by up to 225% and anxiety risk by up to 450%, particularly in boys.
A Gram Research analysis of over 6,500 Australian teenagers found that eating more fruits and drinking fewer sugary drinks may protect against depression and anxiety. Researchers tracked students for three years, measuring what they ate and their mental health symptoms. Teens who ate more fruit had significantly lower rates of depression and anxiety, while those who drank more sugar-sweetened beverages had higher rates of both conditions. The connection was especially strong for boys drinking sugary drinks. These findings suggest that improving diet quality could be an important way to help prevent mental health problems in young people.
Key Statistics
A three-year cohort study of 6,537 Australian adolescents found that higher fruit intake was associated with a 13% lower risk of depression and 7% lower risk of anxiety over the follow-up period.
Among the same cohort of Australian teenagers, higher sugar-sweetened beverage intake was associated with a 225% increased risk of depression and 450% increased risk of anxiety in boys, and 210% increased depression risk and 104% increased anxiety risk in girls.
The longitudinal study tracked 6,537 teenagers from an average age of 12.65 years over three years, with mental health assessments at baseline and at 1, 2, and 3-year follow-ups to establish temporal relationships between diet and mental disorder onset.
The Quick Take
- What they studied: Whether what teenagers eat affects their chances of developing depression or anxiety over time
- Who participated: 6,537 Australian teenagers with an average age of 12.65 years at the start, followed for three years with check-ins at 1, 2, and 3 years
- Key finding: Eating more fruit reduced depression risk by 13% and anxiety risk by 7%. Drinking sugary beverages increased depression risk by 225% and anxiety risk by 450%, especially for boys.
- What it means for you: Eating more fruits and limiting sugary drinks may help protect your mental health, though diet is just one factor among many that influence depression and anxiety
The Research Details
Researchers followed the same group of Australian teenagers over three years, asking them about their diet and mental health at the beginning and then again after 1, 2, and 3 years. This type of study, called a cohort study, is powerful because it tracks real people over time and can show whether diet changes come before mental health changes. The researchers used validated questionnaires, which are surveys that have been tested and proven to accurately measure depression and anxiety. They looked at three specific foods: fruit, vegetables, and sugar-sweetened beverages. To make sure diet was actually causing the mental health changes (not the other way around), they excluded anyone who already had depression or anxiety at the start of the study.
Following the same people over time is much stronger evidence than just comparing people’s diets and mental health at one moment. This approach shows that diet comes first, then mental health changes follow, which suggests a real cause-and-effect relationship. By excluding people who already had depression or anxiety, the researchers could be more confident that diet was actually preventing new cases from developing, rather than just helping people who already had these conditions.
This study has several strengths: it included a large number of participants (6,537), followed them for a full three years, and used validated mental health measures. The researchers also adjusted their analysis for other factors that might affect mental health, like age and sex. However, the study relied on self-reported diet information, which can be less accurate than measured food intake. The study was also conducted in Australia, so results may not apply equally to all countries or populations.
What the Results Show
Eating more fruit was protective against both depression and anxiety. For every additional serving of fruit per day, the risk of developing depression dropped by 13% and the risk of anxiety dropped by 7%. This effect was similar for both boys and girls. The most striking finding involved sugar-sweetened beverages. Teens who drank more sugary drinks had dramatically higher rates of both depression and anxiety. The effect was stronger in boys than girls: boys who drank more sugary beverages had a 225% higher risk of depression and a 450% higher risk of anxiety, compared to boys who drank fewer sugary drinks. Girls also showed increased risk, but it was somewhat lower: 210% higher risk for depression and 104% higher risk for anxiety. Vegetable intake did not show a significant protective effect in this study, which was somewhat surprising given previous research.
The sex differences in sugar-sweetened beverage effects were notable. Boys appeared more vulnerable to the mental health effects of sugary drinks than girls, though both sexes showed increased risk. The researchers also found that the associations between diet and mental health were consistent across the three-year follow-up period, suggesting these are stable, long-term relationships rather than temporary effects.
This study adds important evidence to a growing body of research showing links between diet quality and mental health. Previous studies have suggested that diets high in processed foods and sugar are associated with depression and anxiety, but most were cross-sectional (measuring diet and mental health at the same time). This longitudinal study is stronger because it shows diet changes come before mental health changes. The findings align with research in adults showing similar protective effects of fruit and harmful effects of sugary drinks on mental health.
The study relied on teenagers self-reporting what they ate, which can be inaccurate. The researchers could not measure exactly how much fruit or vegetables were consumed, only whether teens ate them. The study was conducted in Australia, so results may not apply equally to other countries with different food cultures or populations. The study could not prove that diet directly causes mental health changes, only that they are associated. Other factors like sleep, exercise, social relationships, and genetics also influence depression and anxiety risk.
The Bottom Line
Eating more fruit and reducing sugar-sweetened beverages may help protect mental health in teenagers. This is a moderate-strength recommendation based on a well-designed longitudinal study. However, diet is just one piece of mental health. If you or someone you know is struggling with depression or anxiety, talk to a doctor or mental health professional. Improving diet should complement, not replace, professional mental health care.
These findings are most relevant to teenagers, parents of teenagers, and healthcare providers working with young people. The study suggests that dietary changes could be a practical, accessible way to support mental health prevention in adolescence. The findings may also interest educators and school nutrition programs.
Mental health benefits from dietary changes are unlikely to appear overnight. This study tracked changes over three years, suggesting that consistent dietary improvements over months to years may be needed to see meaningful effects on depression and anxiety risk.
Frequently Asked Questions
Can changing my diet help prevent depression and anxiety?
Research shows that eating more fruit and fewer sugary drinks may reduce depression and anxiety risk in teenagers. A three-year study of 6,537 Australian teens found each extra daily fruit serving lowered depression risk by 13%. However, diet is one factor among many; professional help is essential if you’re struggling with mental health.
How much do sugary drinks affect mental health?
According to research reviewed by Gram, teenagers who drank more sugar-sweetened beverages had dramatically higher mental health risks: up to 225% higher depression risk and 450% higher anxiety risk, especially for boys. The effect was consistent over three years of follow-up.
Do vegetables help prevent depression like fruit does?
This particular study found that vegetable intake did not show significant protective effects against depression or anxiety, which was somewhat surprising. However, vegetables remain important for overall health. More research is needed to understand why fruit showed benefits while vegetables did not in this study.
How long does it take to see mental health benefits from diet changes?
This study tracked teenagers over three years, suggesting that consistent dietary improvements over months to years may be needed to see meaningful effects on depression and anxiety risk. Mental health benefits from diet changes are unlikely to appear immediately.
Are boys and girls affected differently by sugary drinks?
Yes, according to the three-year study of 6,537 Australian adolescents, boys showed stronger mental health risks from sugary beverages than girls. Boys had 225% higher depression risk and 450% higher anxiety risk with increased consumption, while girls had 210% and 104% higher risks respectively.
Want to Apply This Research?
- Log daily fruit servings and sugar-sweetened beverage consumption. Set a goal of 2-3 fruit servings per day and track days when you stay below 1 sugary drink per day. Monitor mood or anxiety symptoms weekly using a simple 1-10 scale to see if dietary improvements correlate with mental health changes over time.
- Replace one sugar-sweetened beverage per day with water, unsweetened tea, or a piece of fruit. Add one extra fruit serving to your daily diet. Track these swaps in the app and celebrate weekly consistency. Over time, these small changes may accumulate into meaningful mental health benefits.
- Create a simple dashboard showing weekly fruit intake, weekly sugary drink consumption, and weekly mood/anxiety ratings. Look for patterns over 4-8 weeks to see if increased fruit and decreased sugary drinks correlate with improved mood. Share trends with a healthcare provider if mental health concerns persist.
This research shows associations between diet and mental health in teenagers, but diet is only one factor influencing depression and anxiety. This information is not a substitute for professional mental health care. If you or someone you know is experiencing depression, anxiety, or other mental health concerns, please consult with a qualified healthcare provider, therapist, or counselor. Dietary changes should complement, not replace, professional mental health treatment. Always discuss significant dietary changes with a healthcare provider, especially for teenagers.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.