A major new study has revealed that diets high in ultra-processed foods (UPFs) may significantly raise the risk of developing mental health conditions such as depression, anxiety, and substance use disorders.
The findings are based on data from over 30,000 adults enrolled in the UK Biobank — a long-term health study tracking half a million participants.
Researchers investigated how UPF consumption and related metabolic changes in the body relate to mental health outcomes over time.
UPFs include industrially manufactured foods that contain little to no whole ingredients and are often loaded with additives, preservatives, and artificial flavorings.
- Ultra-processed foods potentially linked to early death
- Weight gain associated with high intake of ultra-processed foods
- High intake of ultra-processed foods associated with lower grades in school
Common examples include packaged snacks, instant meals, sugary cereals, and processed meats.
Participants in the study were tracked for over a decade.
Those who consumed more UPFs were more likely to develop a range of mental health issues, even after accounting for age, lifestyle, and existing health conditions.
Individuals with higher UPF consumption tended to be younger, had higher body fat measures, lower income levels, and generally less healthy habits.
The study also analysed blood samples using advanced metabolomic techniques. This revealed 91 chemical markers in the bloodstream that were strongly linked to UPF intake.
These included changes in fatty acid levels, blood sugar markers, and cholesterol-related compounds.
Both the dietary patterns and the blood-based metabolic profiles independently predicted increased risk of mental health conditions.
Notably, high UPF intake was associated with a 12-year rise in new cases of anxiety, depression, and substance use disorder.
Researchers also examined psychological symptoms such as restlessness, fatigue, suicidal thoughts, and feelings of worthlessness.
High UPF consumption was linked to a greater likelihood of reporting these symptoms — particularly among younger adults.
The metabolic signature associated with UPF intake appeared to partly explain how these foods might influence brain health.
However, in the general population, the blood markers alone were not as strongly tied to day-to-day symptoms unless participants were under the age of 60, suggesting younger people may be more sensitive to diet-related biochemical changes.
The authors said: “Our findings provide further evidence that ultra-processed foods are not just harmful to physical health, but also have serious implications for mental well-being.
“Public health policies should prioritise reducing UPF consumption as part of mental health prevention strategies.”
While the study’s observational nature means it cannot prove a direct cause-and-effect relationship, the researchers believe the consistent links across different mental health outcomes are cause for concern.
- Accelerated biological ageing associated with ultra-processed foods
- High intake of ultra-processed foods can accelerate biological ageing
- Ultra processed foods linked to increased muscle fattiness
They also noted limitations, including the use of self-reported dietary data, and the fact that the sample largely included white British participants — meaning results may not apply equally to all populations.
The research adds to a growing body of evidence suggesting that diet plays a crucial role in mental health.
While previous studies have highlighted the protective benefits of whole foods like vegetables, fruits, and omega-3-rich fish, this study focuses attention on what people should avoid — particularly heavily processed, nutrient-poor foods.
As rates of mental illness continue to rise globally, experts say shifting toward minimally processed diets may offer a low-cost, accessible approach to improving public mental health outcomes.
Read the study in the journal Nutrients.
