Evaluation of two dietary patterns in people with depression: A proof-of-concept trial

INTERVENTION: Participants will attend study visits in‐clinic at baseline and week 4 at the Health Education and Research Building (HERB), Barwon Health, Geelong. A whole‐diet intervention that provides a balance of protein, carbohydrate and fat will be provided to participants for 4 weeks. A 7‐day meal plan, which meets the food group targets of the intervention diet, was developed for two energy levels (Level 1 ‐ 8MJ/day, Level 2 ‐ 10MJ/day). Participants will be allocated to Level 1 or Level 2 based on an assessment of their habitual diet at baseline by a dietitian and may be adjusted at subsequent weekly calls to meet an individual’s energy requirements, based on dietetic assessment (e.g. assessment of individual’s weight, hunger levels). Three meals and three snacks will be provided to participants for the duration of the study. Participants will receive dietary information one‐on‐one from a dietitian at baseline and will be provided with a study booklet developed for the purpose of the study. One‐on‐one baseline and week 4 visits will be approximately 2 hours in duration each. During the intervention, participants will meet weekly with a study investigator (dietitian) online which will be approximately 20 minutes in duration. Diet adherence will be assessed via the completion of daily food adherence logs which will be returned to researchers at the final study visit. CONDITION: Major depressive disorder ; ; Major depressive disorder Mental Health ‐ Depression PRIMARY OUTCOME: Clinician‐rated depressive symptoms assessed using the Montgomery‐Asberg Depression Rating Scale (MADRS).[ Baseline and week 4 post‐diet commencement. ] INCLUSION CRITERIA: INCLUSION CRITERIA: • Adults aged 18‐65 years • Successfully fulfilled the Diagnostic and Statistical manual of Mental Disorders (DSM‐5) diagnostic criteria for a major depressive episode, determined using the SCID‐5‐RV • Moderate or severe depressive symptoms based on score equal to or greater than 20 on MADRS • Poor diet quality (based on an adapted Total Diet Score) • Willing and able to undertake and adhere to the requirements of a 4‐week feeding trial and attend all study appointments • Reside in meal delivery zones • Must be able to read and understand materials written in English • Have access to a smartphone/tablet/computer with internet access and kitchen facilities (e.g., microwave/oven, freezer) • Have a nominated preferred general practitioner SECONDARY OUTCOME: Any change in participants’ overall perception of their depressive symptoms assessed using the Patient Global Impression‐Improvement (PGI‐I) scale.[ Baseline, week 1, week, 2, week 3, week 4 post‐diet commencement.] Body weight measured using calibrated scales in‐clinic.[ Baseline and week 4 post‐diet commencement. ] Brain Derived Neurotrophic Factor (BDNF) measured via serum.[ Baseline and week 4 post‐diet commencement.] C‐reactive protein measured via plasma.[ Baseline and week 4 post‐diet commencement.] Cortisol measured via plasma.[ Baseline and week 4 post‐diet commencement.] Diet acceptability measured using an adapted Diet Acceptability Questionnaire.[ Baseline and week 4 post‐diet commencement.] Diet feasibility assessed via food adherence logs in each group. [ Baseline and week 4 post‐diet commencement. ] Diet tolerability assessed using a gastrointestinal symptom questionnaire. [ Baseline, week 1, and week 4 post‐diet commencement. ] Fasted tryptophan measured via plasma.[ Baseline and week 4 post‐diet commencement.] Gut microbiome composition assessed via analysis of stool samples. [ Baseline and week 4 post‐diet commencement. ; ] Gut microbiome metabolites assessed via analysis of stool samples.[ Baseline and week 4 post‐diet commencement. ] Inflammatory markers (cytokines) measured via plasma.[ Baseline and week 4 post‐diet commencement.] Kynurenine pathway metabolites measured via plasma.[ Baseline and week 4 post‐diet commencement.] Markers of gut permeability (IgA) measured via plasma.[ Baseline and week 4 post‐diet commencement.] Markers of gut permeability (IgG) measured via plasma.[ Baseline and week 4 post‐diet commencement.] Markers of gut permeability (IgM) measured via plasma.[ Baseline and week 4 post‐diet commencement.] Markers of gut permeability (LBP) measured via plasma.[ Baseline and week 4 post‐diet commencement.] Markers of gut permeability (LPS) measured via plasma.[ Baseline and week 4 post‐diet commencement.] Markers of gut permeability (sCD14) measured via plasma.[ Baseline and week 4 post‐diet commencement.] Participant‐rated anxiety symptoms assessed using the Generalised Anxiety Disorder (GAD‐7).[ Baseline and week 4 post‐diet commencement. ] Participant‐rated depressive symptoms assessed using the 9‐item Patient Health Questionnaire (PHQ‐9).[ Baseline, week 2, week 4 post‐diet commencement. ] Participant‐rated quality of life assessed using the World Health Organizations Quality of Life Short Version Scale (WHOQOL‐BREF).[ Baseline and week 4 post‐diet commencement. ] Physical activity assessed using the five‐item Simple Physical Activity Questionnaire (SIMPAQ).[ Baseline and week 4 post‐diet commencement. ] Short‐chain fatty acids measured via serum.[ Baseline and week 4 post‐diet commencement.] Sleep quality assessed using the single‐item sleep quality scale (SQS).[ Baseline and week 4 post‐diet commencement.] Stool consistency assessed using the Bristol Stool Form Scale (BSFS).[ Baseline, week 1, week 4 post‐diet commencement.] Stool frequency assessed using the Bristol Stool Form Scale (BSFS).[ Baseline, week 1, week 4 post‐diet commencement.]