Due to the high prevalence of depression among young adults, identifying prevention strategies during young adulthood are crucial. Dietary polyphenols have been associated with depression in older cohorts; however, the association remains unclear, particularly in young adults. This study aimed to assess the prospective association between the intake of total polyphenols, polyphenol classes, and polyphenol subclasses with depressive symptoms in young adults. Data from 1,484 Raine Study Generation 2 participants [52.7% female; baseline mean age (SD): 20 (0.5)] at the -20, -22, and -27 year follow-ups (N = 964, 979, and 1,094, respectively), with overlap across follow-ups, were used. Energy-adjusted polyphenol intake was estimated from food frequency questionnaire data using our expansion of the AUSNUT 2011-13 and Phenol-Explorer to include polyphenol content data and categorised into quartiles. The primary outcome was self-reported depressive symptoms assessed via the 21-item Depression, Anxiety, and Stress Scale averaged across the three timepoints. Linear mixed-effects models were used to assess the association between the polyphenol intake exposures and depressive symptoms. Sociodemographic characteristics and lifestyle- and health-related behaviours were adjusted for. Participants in the highest quartiles for flavonol and hydroxybenzoic acid intake had lower depressive symptoms across time than participants in the lowest quartiles [flavonols (Q4 v Q1 mean difference: -1.41, 95%CIs: -2.51, -0.31); hydroxybenzoic acids (Q4 v Q1: -1.42, 95%CIs: -2.54, -0.29)]. We found no evidence of a highest versus lowest association for all other polyphenol categories. Future studies are required to investigate whether increasing polyphenol intake could protect against depression in young adults.

This study explored whether lifestyle therapy that promoted adherence to a Mediterranean-style diet as a treatment for depression led to environmental co-benefits. Participants (n 75 complete case) were Australian adults in the Curbing Anxiety and Depression using Lifestyle Medicine non-inferiority, randomised controlled trial, which showed that lifestyle therapy was non-inferior to psychotherapy in reducing depressive symptoms, when delivered in group format via video conferencing over an 8-week treatment period. In this secondary analysis, we hypothesised that the lifestyle arm would be superior to the psychotherapy arm in reducing the environmental impact of self-reported diet over time. Dietary intake derived from FFQ at baseline and 8 weeks was transformed into environmental impact scores by calculating global warming potential (GWP)*. GWP* was calculated for total dietary intake and distinct food groups (Australian Dietary Guidelines and NOVA classifications). Within-arm changes in GWP* over time were calculated using the median difference. Neither arm showed significant changes. Between-arm differences in percentage change in GWP* scores over time were analysed using generalised estimating equations models. No between-arm difference for total GWP* score was found (β = 11·06 (–7·04, 29·15)). When examining distinct food groups, results were mixed. These novel findings contribute to the sparse evidence base that has measured the environmental impact of diets in a clinical trial context. Whilst lifestyle therapy that reduced depressive symptoms did not have clear environmental benefits relative to psychotherapy, nutritional counselling that focuses on the environmental impact of food choices may drive more pronounced planetary co-benefits.

Research on nutraceutical and dietary interventions in psychiatry has grown substantially, but progress is hindered by methodological inconsistencies and limited reporting standards. To address this, the International Society for Nutritional Psychiatry Research presents the first guidelines on clinical trial design, conduct, and reporting for future clinical trials in this area. Recommendations were developed using a Delphi process including eighteen researchers with considerable clinical trial expertise and experience in either methodology, nutraceutical, or dietary interventions in psychiatry. These guidelines provide forty-nine recommendations for clinical trial design and outcomes, five for trial reporting, and seven for future research priorities. The recommendations included in these guidelines are designed to inform both nutraceutical and dietary clinical trial interventions in Nutritional Psychiatry. Common themes include an emphasis on the importance of a multidisciplinary research team and integration of co-design processes into the conduct and design of clinical research, methods to improve transparency and replicability of trial outcomes, and measures to address common biases in nutrition trials. Furthermore, we provide recommendations for future research including examining a greater variety of nutraceutical and dietary interventions, scalable delivery models, effectiveness and implementation studies, and the need to investigate these interventions in the prevention and management of less studied psychiatric conditions (e.g. schizophrenia and bipolar disorder). Recommendations included within these guidelines are intended to improve the rigor and clinical relevance of ongoing and future clinical trials in Nutritional Psychiatry.

People living with mental illness report a broad spectrum of nutrition risks, beyond malnutrition, but appropriate and adequately validated nutrition risk screening tools for mental health settings are lacking. This study aimed to develop a nutrition-risk screening tool, the NutriMental Screener, and to perform preliminary feasibility and validity testing. In an international, stakeholder engaging approach, a multifaceted nutrition-risk screening tool for mental health services was developed by means of workshops with international stakeholders and two online surveys. Feasibility of the NutriMental screener was tested as part of a research study in Switzerland with 196 participants, evenly distributed across the three study groups (sixty-seven outpatients and sixty-five inpatients with psychotic or depressive disorders as well as sixty-four controls without mental illness). The NutriMental screener consists of ten items covering different nutritional issues that indicate the need for referral to a dietitian or clinical nutritionist. Almost all patients (94·7 %) reported at least one nutrition risk by means of the NutriMental screener. Prevalence for nutrition risks via NutriMental screener was higher in patients than in controls. Almost every second patient expressed a desire for nutritional support (44·7 %). After further validity testing is completed, there is the potential for the NutriMental Screener to replace malnutrition screening tools as routine screening in various mental health settings aiming to organise nutritional therapy prescriptions in a more targeted and efficient manner.

Depression is a multifaceted condition with diverse underlying causes. Several contributing and inter-related factors such as genetic, nutritional, neurological, physiological, gut-brain-axis, metabolic and psychological stress factors play a role in the pathophysiology of depression. This review aims to highlight the role that nutritional factors play in the aetiology of depression. Secondly, we discuss the biomedical and functional pathology tests which measure these factors, and the current evidence supporting their use. Lastly, we make recommendations on how practitioners can incorporate the latest evidence-based research findings into clinical practice. This review highlights that diet and nutrition greatly affect the pathophysiology of depression. Nutrients influence gene expression, with folate and vitamin B12 playing vital roles in methylation reactions and homocysteine regulation. Nutrients are also involved in the tryptophan/kynurenine pathway and the expression of brain-derived neurotrophic factor (BDNF). Additionally, diet influences the hypothalamic-pituitary-adrenal (HPA) response and the composition and diversity of the gut microbiome, both of which have been implicated in depression. A comprehensive dietary assessment, combined with appropriate evaluation of biochemistry and blood pathology, may help uncover contributing factors to depressive symptoms. By employing such an approach, a more targeted and personalised treatment strategy can be devised, ultimately leading to improved patient outcomes.

Emerging evidence suggests that diet therapy (nutrients, foods and dietary patterns) could be effective as a potential adjunctive treatment option for major depressive disorder. Numerous mechanisms have been proposed, including the role inflammation, oxidative stress, brain-derived neurotrophic factor, the gastrointestinal tract microbiome and tryptophan/serotonin metabolism. Despite known differences in depression characteristics and treatment responses between males and females, there are limited sex-specific studies examining the role of diet in young men specifically. This is important as young men are often reluctant to seek mental health support, so finding treatment strategies which appeal to this demographic is crucial. This brief report provides an overview of the most recent advances in the use of diet for preventing and treating depression in young men, highlighting existing challenges and opportunities for future research. We recommend that clinicians discuss the role of diet with depressed young men, so that diet may be used alongside current treatment options.