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Background: Emerging evidence indicates that gut microbiota-targeted interventions may lead to improvements in cognition. We assessed whether a prebiotic-rich dietary intervention, probiotic supplement, or synbiotic combination of both would improve human cognition, as part of the 'Gut Feelings' trial., Methods: An 8-week, 2 × 2 factorial randomised controlled trial was conducted on 118 adults with low mood and potential for dietary improvement. Treatment arms: (1) probiotic supplement and diet-as-usual (probiotic group); (2) high-prebiotic diet and placebo supplement (prebiotic diet group); (3) probiotic supplement and high-prebiotic diet (synbiotic group); and (4) placebo supplement and diet-as-usual (placebo group). At baseline and 8-weeks, the Cogstate Brief Battery was administered, testing processing speed, attention, visual learning, and working memory. Data were analysed using Bayesian linear regression., Results: We found weak evidence that the probiotic improved working memory (Cohen's d  = -0.32, 95% CI: -0.67, 0.03; posterior probability [post. prob] of benefit: 96%). For the other treatments, there was little or no evidence of cognitive improvement. We found weak evidence that the prebiotic diet impaired processing speed ( d  = 0.25, 95% CI: -0.02, 0.51; post. prob of harm: 97%). There was little indication of a synergistic interaction between the probiotic and prebiotic diet., Conclusion: We found suggestive evidence of a probiotic-induced improvement in working memory, and prebiotic-induced impairment in processing speed. However, the evidence remains inconclusive regarding any cognitive benefit or harm induced by the probiotic, prebiotic diet, or synbiotic treatments. Larger intervention studies are recommended, with inclusion of neuroimaging or electrophysiology measures. Trial Registration: Australian New Zealand Clinical Trials Registry (ACTRN12617000795392; registered 31 May 2017).

Objectives: In experimental models, the prenatal diet influences gut microbiota composition in mothers and offspring; however, it is unclear whether this occurs in humans. We investigated the effects of a gut-focused perinatal dietary intervention on maternal and infant gut microbiota composition four weeks after birth., Methods: This randomised controlled trial randomised pregnant women to receive dietary advice as part of standard care, or additionally receive a dietary intervention focused on the Australian Dietary Guidelines and increasing prebiotic and probiotic/fermented food intakes (ACTRN12616000936426). Study assessments occurred from gestation week 26 (baseline) to four weeks postpartum (follow-up). Faecal samples, collected at baseline for mothers, and follow-up for mothers and infants, underwent 16SrRNA sequencing. The primary outcome was a between-group mean difference in infant faecal Shannon index. Secondary outcomes included between-group differences in other microbiota measures, including maternal change from baseline CLR-transformed Prevotella abundance., Results: Forty-four women and 45 infants completed the study. The mean Shannon index of infants in the intervention group was -0.35 (95% CI: -0.64, -0.06, SD: 0.52) units lower than control group infants, corresponding to a medium effect size (Cohen's D: -0.74, 95% CI: -1.34, -0.13). The findings were similar using other metrics of α-diversity. There were no between-group differences in β-diversity, nor any differentially abundant taxa in infants. The intervention increased abundances of the genus Prevotella in mothers compared to controls., Discussion: This gut-focused perinatal dietary intervention was associated with differences in the maternal and infant gut microbiota composition. Larger studies are required to replicate and extend these findings.

Background: Mood disorders, including unipolar and bipolar depression, contribute significantly to the global burden of disease. Psychological therapy is considered a gold standard non-pharmacological treatment for managing these conditions; however, a growing body of evidence also supports the use of lifestyle therapies for these conditions. Despite some clinical guidelines endorsing the application of lifestyle therapies as a first-line treatment for individuals with mood disorders, there is limited evidence that this recommendation has been widely adopted into routine practice. A key obstacle is the insufficient evidence on whether lifestyle therapies match the clinical and cost effectiveness of psychological therapy, particularly for treating those with moderate to severe symptoms. The HARMON-E Trial seeks to address this gap by conducting a non-inferiority trial evaluating whether a multi-component lifestyle therapy program is non-inferior to psychological therapy on clinical and cost-effectiveness outcomes over 8-weeks for adults with major depressive disorder and bipolar affective disorder., Methods: This trial uses an individually randomised group treatment design with computer generated block randomisation (1:1). Three hundred and seventy-eight adults with clinical depression or bipolar affective disorder, a recent major depressive episode, and moderate-to-severe depressive symptoms are randomised to receive either lifestyle therapy or psychological therapy (adjunctive to any existing treatments, including pharmacotherapies). Both therapy programs are delivered remotely, via a secure online video conferencing platform. The programs comprise an individual session and six subsequent group-based sessions over 8-weeks. All program aspects (e.g. session duration, time of day, and communications between participants and facilitators) are matched except for the content and program facilitators. Lifestyle therapy is provided by a dietitian and exercise physiologist focusing on four pillars of lifestyle (diet, physical activity, sleep, and substance use), and the psychological therapy program is provided by two psychologists using a cognitive behavioural therapy approach. Data collection occurs at baseline, 8-weeks, 16-weeks, and 6 months with research assistants blinded to allocation. The primary outcome is depressive symptoms at 8 weeks, measured using the Montgomery-Åsberg Depression Rating Scale (MADRS) (minimal clinically important difference = 1.6). A pre-specified within-trial economic evaluation will also be conducted., Discussion: Should lifestyle therapy be found to be as clinically and cost effective as psychological therapy for managing mood disorders, this approach has potential to be considered as an adjunctive treatment for those with moderate to severe depressive symptoms., Trial Registration: Australia and New Zealand Clinical Trials Register (ANZCTR): ACTRN12622001026718, registered 22nd July 2022., Protocol Version:  4.14, 26/06/2024., (© 2024. The Author(s).)

Mechanical bowel preparation (MBP) is essential for visualisation of the colon during colonoscopy. Previous studies have identified changes in gut microbiota composition after MBP and colonoscopy. Considering the gut microbiota is increasingly implicated in psychiatry, we explored the potential impact of this intervention on mood and the microbiota-gut-brain axis. We conducted a pre-post intervention study in adults, with timepoints of one week before and one month after MBP and colonoscopy. Our primary outcome was change in average Hospital Anxiety and Depression Scale depression sub-scores. We examined changes in average anxiety, stress, and quality of life scores and gut microbiota composition using 16S rRNA sequencing. We further explored associations between changes in depressive symptoms and gut microbiota and conducted post hoc analyses to explore potential effect modifiers. Average depressive symptom scores decreased one month post-procedure compared to baseline (n = 59; adjusted β = -0.64; 95%CI: -1.18, -0.11). Irritable bowel syndrome (IBS) appeared to moderate this relationship (β = 1.78; 95%CI: 0.292, 3.26); depressive symptoms increased in those with, and decreased in those without, IBS. Reduced alpha diversity, modest effects on beta-diversity, and increases in health-associated genera were observed one month post-procedure. Increases in the CLR-transformed abundances of Ruminococcaceae UCG-009 were associated with improvements in depressive symptoms. There is preliminary evidence of a potential mental health effect of MBP and colonoscopy, particularly for those with IBS, which may be associated with changes to the gut microbiota. Further research is required to confirm these findings and their clinical relevance.

Emerging evidence suggests that the human vermiform appendix is not a vestigial organ but rather an immunological organ of biological relevance. It is hypothesised that the appendix acts as a bacterial 'safe house' for commensal gut bacteria and facilitates re-inoculation of the colon after disruption through the release of biofilms. To date, no studies have attempted to explore this potential mechanistic function of the appendix. We conducted a pre-post intervention study in adults (n = 59) exploring re-establishment of the gut microbiota in those with and without an appendix after colonic disruption via bowel preparation and colonoscopy. Gut microbiota composition was measured one week before and one month after bowel preparation and colonoscopy using 16S rRNA sequencing. We observed between group differences in gut microbiota composition between those with (n = 45) and without (n = 13) an appendix at baseline. These differences were no longer evident one-month post-procedure, suggesting that this procedure may have 'reset' any potential appendix-related differences between groups. Both groups experienced reductions in gut microbiota richness and shifts in beta diversity post-procedure, with greater changes in those without an appendix, and there were five bacterial genera whose re-establishment post-procedure appeared to be moderated by appendicectomy status. This small experimental study provides preliminary evidence of a potential differential re-establishment of the gut microbiota after disruption in those with and without an appendix, warranting further investigation into the potential role of the appendix as a microbial safe house.

Our aim was to conduct an umbrella review of evidence from meta-analyses of observational studies investigating the link between sugar-sweetened beverage consumption and human health outcomes. Using predefined evidence classification criteria, we evaluated evidence from 47 meta-analyses encompassing 22,055,269 individuals. Overall, 79% of these analyses indicated direct associations between greater sugar-sweetened beverage consumption and higher risks of adverse health outcomes. Convincing evidence (class I) supported direct associations between sugar-sweetened beverage consumption and risks of depression, cardiovascular disease, nephrolithiasis, type 2 diabetes mellitus, and higher uric acid concentrations. Highly suggestive evidence (class II) supported associations with risks of nonalcoholic fatty liver disease and dental caries. Out of the remaining 40 meta-analyses, 29 were graded as suggestive or weak in the strength of evidence (classes III and IV), and 11 showed no evidence (class V). These findings inform and provide support for population-based and public health strategies aimed at reducing sugary drink consumption for improved health.

Background: We conducted the first non-inferiority, randomised controlled trial to determine whether lifestyle therapy is non-inferior to psychotherapy with respect to mental health outcomes and costs when delivered via online videoconferencing., Methods: An individually randomised, group treatment design with computer-generated block randomisation was used. Between May 2021-April 2022, 182 adults with a Distress Questionnaire-5 score = ≥8 (indicative depression) were recruited from a tertiary mental health service in regional Victoria, Australia and surrounds. Participants were assigned to six 90-min sessions over 8-weeks using group-based, online videoconferencing comprising: (1) lifestyle therapy (targeting nutrition, physical activity) with a dietitian and exercise physiologist (n = 91) or (2) psychotherapy (Cognitive Behavioural Therapy) with psychologists (n = 91). The primary outcome was Patient Health Questionnaire-9 (PHQ-9) depression at 8-weeks (non-inferiority margin ≤2) using Generalised Estimating Equations (GEE). Cost-minimisation analysis estimated the mean difference in total costs from health sector and societal perspectives. Outcomes were assessed by blinded research assistants using Computer Assisted Telephone Interviews. Results are presented per-protocol (PP) and Intention to Treat (ITT) using beta coefficients with 95% Confidence Intervals (CIs)., Findings: The sample was 80% women (mean: 45-years [SD:13.4], mean PHQ-9:10.5 [SD:5.7]. An average 4.2 of 6 sessions were completed, with complete data for n = 132. Over 8-weeks, depression reduced in both arms (PP: Lifestyle (n = 70) mean difference:-3.97, 95% CIs:-5.10, -2.84; and Psychotherapy (n = 62): mean difference:-3.74, 95% CIs:-5.12, -2.37; ITT: Lifestyle (n = 91) mean difference:-4.42, 95% CIs: -4.59, -4.25; Psychotherapy (n = 91) mean difference:-3.82, 95% CIs:-4.05, -3.69) with evidence of non-inferiority (PP GEE β:-0.59; 95% CIs:-1.87, 0.70, n = 132; ITT GEE β:-0.49, 95% CIs:-1.73, 0.75, n = 182). Three serious adverse events were recorded. While lifestyle therapy was delivered at lower cost, there were no differences in total costs (health sector adjusted mean difference: PP AUD$156 [95% CIs -$182, $611, ITT AUD$190 [95% CIs -$155, $651] ]; societal adjusted mean difference: PP AUD$350 [95% CIs:-$222, $1152] ITT AUD$ 408 [95% CIs -$139, $1157]., Interpretation: Remote-delivered lifestyle therapy was non-inferior to psychotherapy with respect to clinical and cost outcomes. If replicated in a fully powered RCT, this approach could increase access to allied health professionals who, with adequate training and guidelines, can deliver mental healthcare at comparable cost to psychologists., Funding: This trial was funded by the Australian Medical Research Future Fund (GA133346) under its Covid-19 Mental Health Research Grant Scheme., Competing Interests: This trial was funded by the National Health and Medical Research Council’s (NHMRC) Medical Research Future Fund–COVID-19 Mental Health Research Australian Government Department of Health (GA133346). AO is supported by a NHMRC Emerging Leader 2 Fellowship (2009295). FNJ is supported by an NHMRC Investigator Grant (#1194982). FNJ has received fellowship funding support from the National Health and Medical Research Council (#1194982) and payment or honorariums for lectures, presentations, speakers bureaus, manuscript writing, or educational events from the Malaysian Society of Gastroenterology and Hepatology, JNPN Congress, American Nutrition Association, Personalised Nutrition Summit, and American Academy of Craniofacial Pain, is a Scientific Advisory Board member of Dauten Family Centre for Bipolar Treatment Innovation (unpaid) and Zoe Nutrition (unpaid), has written two books for commercial publication on the topic of nutritional psychiatry and gut health, and is the principal investigator for the MicroFit Study. She is Director of the Food & Mood Centre, Deakin University, which has received research funding support from Be Fit Food, Bega Dairy and Drinks, and the a2 Milk Company and philanthropic research funding support from the Waterloo Foundation, Wilson Foundation, the JTM Foundation, the Serp Hills Foundation, the Roberts Family Foundation, and the Fernwood Foundation. SR is supported by an NHMRC Investigator Grant (2017506). MB is supported by a NHMRC Senior Principal Research Fellowship and Leadership 3 Investigator grant (1156072 and 2017131). MTey is supported by a NHMRC Emerging Leadership Fellowship (APP1195335). JS is supported by core funding to the Australian Centre for Behavioural Research in Diabetes provided by the collaboration between Diabetes Victoria and Deakin University. VV is supported by the Rural Health Multidisciplinary Training program. SMah has received funding from Education in Nutrition to provide a professional development presentation and Red Island Olive Oil for social media promotion. MMor has received research grants related to antimicrobial stewardship, discharge medication, consulting fees from Primary Health Networks of Gold Coast and Western Australia related to Primary Sense software. Australian Health Policy Collaboration, RACGP, Australian Department of Health and Aged Care (DoHAC), conference support from RACGP various as chair of Expert Committee for Quality Care, participation in DSMBs for Primary Sense and DoHAC and is a member of Arthritis Australia and Bond University Boards. The contents of the published material are solely the responsibility of the individual authors and do not reflect the views of the funding bodies. The authors have no interests to declare., (© 2024 The Authors.)

Background & Aims: We aimed to analyze the prospective association between adherence to the ultra-processed dietary pattern and risk of depressive outcomes using original data from the NutriNet Brasil cohort and via a systematic review and meta-analysis of observational studies that have investigated the same association., Methods: In our original research analysis, we used data from 15,960 adults (≥18 y) participating in the NutriNet Brasil cohort study, free of depression or depressive symptoms during the baseline (77.5% women, 45.8 ± 13.0 y). The mean dietary share of ultra-processed foods (%Kcal/d), calculated from two baseline 24-h dietary recalls, was used to measure the adherence to the ultra-processed dietary pattern. New cases of depressive symptoms were assessed using the Patient Health Questionnaire-9 over the follow-up period (mean: 18.3 months). Cox proportional hazards models were used for the main analyses. In our systematic review and meta-analysis, we incorporated effect estimates from six prospective cohort studies that have examined the same association, including ours., Results: In the adjusted model, each 10% increase in the dietary share of ultra-processed foods was associated with a 10% increase in the hazard of incident cases of depressive symptoms (HR:1.10; 95%CI: 1.07-1.14). This association was slightly attenuated in the models including potential mediators. In our meta-analysis of six prospective studies, high versus low exposure to ultra-processed foods was associated with a summary hazard ratio of depressive outcomes of 1.32; 95%CI: 1.19-1.46; I 2 : 71%., Conclusion: A higher adherence to the ultra-processed dietary pattern was associated with a higher risk of developing depressive outcomes in the NutriNet Brasil cohort and in the meta-analysis., Competing Interests: Conflict of interest None declared., (Copyright © 2024 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.)

Background: Diet is fundamental to the care of irritable bowel syndrome (IBS). However, some approaches are not appropriate for individuals experiencing psychological symptoms., Aims: To assess feasibility of a Mediterranean diet in IBS and its impact on gastrointestinal and psychological symptoms., Methods: We recruited adults with Rome IV IBS and mild or moderate anxiety and/or depressive symptoms to an unblinded 6-week randomised controlled trial. Patients were randomised to Mediterranean diet counselling or habitual diet. We collected gastrointestinal and psychological symptom data, dietary data and stool samples for metagenomic sequencing., Results: We randomised 59 individuals (29 Mediterranean diet, 30 control); 48 completed the study. The Mediterranean Diet Adherence Screener score was higher in the Mediterranean diet group than controls at week 6 (7.5 [95% CI: 6.9-8.0] vs. 5.7 [5.2-6.3], p < 0.001), and there was a greater score increase than controls (2.1 [95% CI: 1.3-2.9] vs. 0.5 [95% CI: 0.1-1.0], p = 0.004), demonstrating Mediterranean diet feasibility. There was a greater proportion of gastrointestinal symptom responders in the Mediterranean diet group than controls (24/29, 83% vs. 11/30, 37%, p < 0.001) and depression responders (15/29, 52% vs. 6/30 20%, p = 0.015). There was no difference in FODMAP intake at week 6 (p = 0.51). Gastrointestinal adverse events were similar (p = 0.588). There were no differences in change in microbiome parameters between groups., Conclusions: A Mediterranean diet is feasible in IBS and leads to improvement in gastrointestinal and psychological symptoms. Although this study was unblinded, these findings together with the broader benefits of the Mediterranean diet, provide strong impetus for future research in IBS. Australia New Zealand Clinical Trials Registry: ACTRN12620001362987., (© 2023 The Authors. Alimentary Pharmacology & Therapeutics published by John Wiley & Sons Ltd.)

Objectives: To examine the association between high intakes of ultra-processed foods (UPF) and recurrence of depressive symptoms (DepS) in a Western non-Mediterranean country and its contribution to the overall diet-depression relationship., Methods: Analyses were carried out on British participants from the Whitehall II cohort. Present analyses were restricted to white participants N  = 4554 (74% men, mean age = 61; SD = 5.9). UPF consumption was estimated from a 127-item food frequency questionnaire using the NOVA classification, and cumulative average of UPF intakes (g/day) over 11 years of exposure (1991/1994-2002/2004) was computed. Recurrent DepS after measurement of UPF was defined as having two or more episodes of DepS (the Center for Epidemiologic Studies Depression Scale (CES-D) score ≥ 16 or antidepressants use) during four phases of follow-up (2002/2004-2015/2016)., Results: Over the follow-up, 588 (12.9%) cases of recurrent DepS were observed. After adjusting for socio-demographic factors, health behaviours and health status, participants in top quintile of UPF intakes [mean 33% of total daily intakes in grams] had 31% higher odds of recurrent DepS (odds ratio 1.31; 95% CI 1.04-1.64) compared to participants in the four lowest quintiles of UPF [mean 18.1% of total daily intakes in grams]. Additional analyses showed that associations between adherence to several diet quality measures and recurrent DepS were partially attenuated (17-27%) by UPF intakes., Conclusion: In this British population, high intakes of ultra-processed foods were associated with increased odds of recurrent depressive symptoms and contributed to the overall diet quality-depressive symptoms association.