Ultra-processed foods increase risk of anxiety and depression, study shows

A major population study reveals that diets high in ultra-processed foods are tied to poorer mental health, and uncovers biological markers that help explain the link.

Study: Associations of Ultra-Processed Food Intake and Its Circulating Metabolomic Signature with Mental Disorders in Middle-Aged and Older Adults. Image Credit: Lightspring / Shutterstock

In a recent study published in the journal Nutrients, researchers assessed the associations of ultra-processed foods (UPFs) and related metabolic signatures with mental disorders.

Mental disorders, including conditions like anxiety, substance use disorder (SUD), and depression, are major contributors to global disease and disability burden. Despite therapeutic advances, mental disorder prevalence has remained stagnant in the past decades, highlighting the need for complementary preventive strategies aimed at modifiable risk factors.

Dietary habits play a crucial role in the development and progression of mental disorders. In particular, diets rich in omega-3 fatty acids, vegetables, and fruits are associated with a reduced risk of mental disorders, whereas Western and pro-inflammatory diets rich in saturated fats and refined carbohydrates elevate the risk. UPFs are mass-produced foods that undergo multiple steps of processing and contain limited whole-food content.

UPF intake has steadily increased, driven by the globalization and urbanization of food systems. Despite substantial evidence implicating UPFs in mental health disturbances, the underlying mechanisms remain unclear. The poor nutritional profile of UPFs, characterized by minimal dietary fiber, higher calories, and excessive sugars, sodium, and saturated fats, has been linked to a heightened risk of various chronic conditions.

About the study

In the present study, researchers examined associations of UPF intake and related metabolic signatures with mental disorders. Data from the United Kingdom Biobank (UKB), a large prospective cohort of over 500,000 participants, were used. The UKB collected extensive information on sociodemographics, biological factors, and lifestyle. Participants were excluded if they lacked metabolomic measurements and dietary data or had prior mental disorder diagnoses.

Dietary intake data were obtained using a self-administered dietary assessment tool. High-throughput nuclear magnetic resonance spectroscopy was performed on plasma samples to quantify circulating metabolic profiles. The primary outcomes were incident overall mental disorders, SUD, depressive disorder, or anxiety disorder. Secondary outcomes included 19 psychological symptoms.

These specific symptoms were unhappiness, meaningless feeling, unhappiness with health, feelings of anxiety, foreboding, excessive worry, irritability, restlessness, trouble relaxing, appetite changes, anhedonia, uncontrolled worry, feelings of depression, fatigue, trouble concentrating, feelings of inadequacy, psychomotor changes, sleeping problems, and suicidal ideation.

Potential confounders were age, sex, body mass index (BMI), index of multiple deprivation (IMD), prevalent diseases, healthy lifestyle factors, and waist-to-hip ratio (WHR). Metabolic features linked to UPF intake were identified using an elastic net regression model. Cox proportional hazards regression models examined the associations of UPF intake and related metabolic signatures with mental disorders.

The basic model was adjusted for age, sex, BMI, and IMD. The multivariable model was additionally adjusted for lifestyle factors, prevalent diseases, and WHR. The mutually adjusted model included both UPF intake and its related metabolic signature to analyze the independence of their associations with mental health outcomes. Further, logistic regression models were used to examine associations with specific psychological symptoms.

Study workflow. A total of 30,059 UK Biobank participants were included in this study, with a median follow-up of 12.6 years. (A) Study flowchart detailing participant selection, exclusion criteria, and final cohort. (B) Definition of ultra-processed food (UPF) intake and the composition of constructed metabolic signature. (C) Cox proportional hazards regression models were employed to evaluate associations of UPF intake and its metabolic signature with the incident risks of overall mental disorder, depressive disorder, anxiety disorder, and substance use disorder, with hazard ratios (HRs) and 95% confidence intervals (CIs) estimated. Logistic regression models were employed to evaluate associations of UPF intake and its metabolic signature with the risks of specific psychological symptoms, with odds ratios (ORs) and 95% CIs estimated. Subgroup analyses were conducted stratified by age and sex. (D) Mediation analyses were applied to investigate the mediating effect of UPF-related metabolic signature. SUD indicates substance use disorder.

Findings

The study included 30,059 participants aged 56.5 years, on average. Overall, 7,594 individuals developed mental disorders over a median follow-up of 12.6 years. Of these, 892, 865, and 1,300 subjects developed anxiety disorder, depressive disorder, and SUD, respectively. Subjects with higher UPF intake were likely to be younger and have higher body BMI, WHR, higher levels of deprivation (lower socioeconomic status based on IMD scores), and unhealthy lifestyles.

Elastic net regression identified 91 metabolites associated with UPF consumption, which spanned various biochemical categories including fatty acids, lipoproteins (like HDL cholesterol ratios), glucose-related metabolites, and amino acids (like valine). Participants with high UPF intake had higher risks of overall mental disorders, anxiety disorder, depressive disorder, and SUD than those with low UPF intake. Similarly, a higher UPF-linked metabolic signature was associated with higher risks of all four mental health outcomes. Subgroup analyses suggested these associations could be stronger in certain groups; for instance, the link between the metabolic signature and SUD was more evident in females, and associations for UPF intake with SUD, and the metabolic signature with depression and anxiety, were stronger in those under 60 years old.

A mediation analysis showed that the UPF-linked metabolic signature partially mediated the associations between UPF consumption and mental disorder risks. Furthermore, higher intake of UPFs was associated with elevated risks of various mental health symptoms, including suicidal ideation, feelings of anxiety, and unhappiness with health. Conversely, the UPF-linked metabolic signature showed no significant associations with mental health symptoms in the overall population, although subgroup analyses revealed associations between the signature and symptoms like unhappiness with health and depressive feelings, specifically in individuals under 60 years old.

Associations of ultra-processed food intake and its metabolic signature with symptoms of mental health and stratified by age. The symptoms included three categories, namely subjective well-being (3 items), PHQ-9 (9 items), and GAD-7 (7 items). Logistic regression models were employed to evaluate associations of ultra-processed food (UPF) intake and its metabolic signature with the risks of specific psychological symptoms. (A) For UPF intake. (B) For metabolic signature. The results were presented with odds ratios (ORs) per 10% increment for UPF intake and ORs per SD increment for metabolic signature. Colors depict significance levels after false discovery rate correction (significant-blue and not significant-gray).

Conclusions

In sum, UPF intake was significantly associated with higher risks of overall mental disorders, anxiety disorder, SUD, and depressive disorder. The UPF-related metabolic signature was also independently associated with increased risks of these mental disorders; it also partially mediated the association between UPF consumption and psychiatric outcomes. The researchers noted limitations, including the study population being predominantly White UK residents, the reliance on self-reported data, the cross-sectional nature of metabolite measurement, and potential residual confounding, which means findings should be interpreted with caution. Thus, the findings suggest that improving diet quality and reducing UPF consumption may help maintain mental well-being.

Journal reference:

• Yuan S, Zhu T, Gu J, et al. Associations of Ultra-Processed Food Intake and Its Circulating Metabolomic Signature with Mental Disorders in Middle-Aged and Older Adults. Nutrients, 2025, DOI: 10.3390/nu17091582,

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