Summary: New analysis adds to growing evidence that changing diet and lifestyle can improve depressive symptoms. The research shows that modest dietary changes—eating more nutrient-dense foods and reducing refined sugars and fast food—are associated with reduced symptoms of depression, while effects on anxiety are less clear.
Source: University of Manchester
An analysis of data from nearly 46,000 people finds dietary improvement reduces depressive symptoms
Key finding: A pooled analysis of randomized controlled trials indicates that weight-loss plans, nutrient-boosting diets and reduced-fat diets can each help reduce symptoms of depression.
Dr Joseph Firth, Honorary Research Fellow at The University of Manchester and Research Fellow at the NICM Health Research Institute at Western Sydney University, explains that until now the overall evidence for whether improving diet benefits mental health had not been comprehensively assessed. To address that gap, Dr Firth and colleagues compiled and analysed all available randomized controlled trials that tested dietary interventions for mental health outcomes.
The meta-analysis, published in Psychosomatic Medicine, combined data from 16 trials that reported on depressive or anxiety symptoms following dietary interventions. In total, the trials provided outcome data from 45,826 participants, most of whom were drawn from non-clinical populations rather than patients with diagnosed depressive disorders.
The analysis found a consistent and statistically significant reduction in depressive symptoms following dietary improvement (effect size g = 0.275). This beneficial effect was observed across different types of dietary approaches: interventions focused on weight loss, on reducing dietary fat, or on increasing nutrient density (for example, more vegetables and fibre) showed similar improvements in mood. The benefit remained visible in higher-quality trials and when dietary programs were compared to both inactive and active control conditions.
Dr Firth notes that these results are encouraging because they suggest that highly specialised diets are not necessary for most people. “The similar effects from different types of dietary improvement suggest that simple, achievable changes are sufficient,” he said. In practice, this means shifting towards meals rich in fibre and vegetables and cutting back on fast foods and refined sugars, rather than adopting complex or narrowly focused regimens.
The study also examined anxiety outcomes and found no clear overall effect of dietary interventions on anxiety symptoms. However, subgroup analyses showed that studies conducted with female samples reported larger benefits for both depression and anxiety, a finding the authors say requires further investigation to understand the reasons behind sex differences.
Dr Brendon Stubbs, a co-author and Clinical Lecturer at the NIHR Maudsley Biomedical Research Centre and King’s College London, highlighted the value of combining lifestyle changes. “When dietary interventions were delivered alongside exercise, participants experienced greater improvements in depressive symptoms,” he said. The authors emphasise that diet and regular physical activity together represent a practical, accessible approach that could complement existing treatments for low mood.
The research team cautions that more work is needed to determine which components of dietary change most strongly influence mental health, and to clarify the biological or behavioural mechanisms involved. Potential pathways include reductions in obesity, inflammation and fatigue—each of which is linked to both diet and mood. The authors also call for additional trials that evaluate dietary interventions in people with clinically diagnosed psychiatric disorders to understand clinical utility and implementation best practices.
Institutional source: University of Manchester
Publisher context: Article summarises a meta-analysis published in Psychosomatic Medicine examining dietary interventions for depression and anxiety.
Original research: Meta-analysis titled “The effects of dietary improvement on symptoms of depression and anxiety: a meta-analysis of randomized controlled trials” by Joseph Firth et al., published February 5, 2019. DOI: 10.1097/PSY.0000000000000673
Abstract (summary of the meta-analysis)
Objective: Poor diet can harm mental health, but the overall effect of dietary interventions on mood and psychological well-being had not been systematically assessed. This study conducted a systematic review and meta-analysis to evaluate the effects of dietary interventions on symptoms of depression and anxiety.
Method: Major electronic databases were searched through March 2018 for randomized controlled trials of dietary interventions reporting changes in depressive or anxiety symptoms in clinical and non-clinical populations. Random-effects meta-analyses estimated effect sizes (Hedges’ g with 95% confidence intervals) for dietary interventions versus control conditions. Subgroup and meta-regression analyses explored potential sources of heterogeneity.
Results: Sixteen eligible RCTs providing outcome data for 45,826 participants were included; most studies sampled non-clinical populations. Dietary interventions significantly reduced depressive symptoms (g = 0.275, 95% CI = 0.10–0.45, p = 0.002). Similar effects were seen in higher-quality trials and when comparing interventions to both inactive and active controls. No significant overall effect was found for anxiety symptoms. Trials with predominantly female samples tended to show larger benefits for both depression and anxiety.
Conclusions: Dietary interventions show promise as an approach to reduce depressive symptoms at the population level. Future research should identify which dietary components are most effective, clarify underlying mechanisms, and develop practical delivery methods for clinical and public health settings.