Efficacy of a Culturally-adapted Mediterranean Diet Intervention on Depression in Relation to the Gut Microbiome

NCT07442799 | Not Yet Recruiting

• 1 other identifier: PSY035
• Study Type: interventional
• Target: 90
• Locations: 1 country
• Sites: 1

Brief Summary

The objective of this study is to investigate the efficacy of a culturally-adapted Mediterranean diet, in accordance with clinical guidelines and research evidence, in reducing depressive symptoms among Hong Kong Chinese adults. Additionally, this study will also explore the potential underlying role of the gut microbiome in the relationship between the Mediterranean diet and depression. This study serves as a pioneering attempt to examine the efficacy and intervention acceptability of a culturally-adapted Mediterranean diet in managing depressive symptoms. Several studies have demonstrated the relationship between diet and mood, while existing studies suggest that consistently adhering to the Mediterranean diet may yield a more pronounced antidepressant effect. Considering that depression is often associated with low motivation, dietary interventions that require active participation may encounter implementation challenges and potentially impact the adherence rate. To address this issue, our study proposes using ecological momentary assessment (EMA), which involves sending frequent reminders to participants, allowing us to examine diet quality and adherence as well as changes in depressive symptoms at various time points. This approach also minimizes potential recall bias and enhances data collection accuracy. If the hypothesis is supported, dietary intervention could emerge as a promising therapeutic strategy for alleviating depressive symptoms. Furthermore, this study could provide insights into the role of the gut microbiome as a potential underlying mechanism between diet and depressive symptoms. The findings could have significant implications for clinical practice.

Conditions

Depression

Keywords

Depression; Ecological momentary assessment; Randomised controlled trial; The Microbiota-Gut-Brain Axis; Mediterranean diet

Outcome Measures

Primary Outcomes (1)

• Change in the Patient Health Questionnaire-9 (PHQ-9)

  The PHQ-9 is a 9-item questionnaire used for screening, diagnosing, monitoring and measuring the severity of depression, which scores each of the nine DSM-IV criteria from "0" (not at all) to "3" (nearly every day).

  Baseline, immediate post-intervention, and 12-week follow-up

Secondary Outcomes (11)

• Change in the Generalized Anxiety Disorder 7-item Scale (GAD-7)

  Baseline, immediate post-intervention, and 12-week follow-up

• Change in the Insomnia Severity Index (ISI)

  Baseline, immediate post-intervention, and 12-week follow-up

• Change in the adapted version of the Modified Mediterranean Diet Score (ModiMedDiet Score)

  Baseline, immediate post-intervention, and 12-week follow-up

• Change in the Seven-day Food Record (7dFR)

  Baseline, immediate post-intervention, and 12-week follow-up

• Change in the International Physical Activities Questionnaire-Chinese version (IPAQ-C)

  Baseline, immediate post-intervention, and 12-week follow-up

Study Arms (2)

Mediterranean diet (MediDiet) group

EXPERIMENTAL

Participants in MediDiet group will receive a culturally adapted Mediterranean diet prepared by the research team on a daily basis. This diet is designed by a certified dietitian based on clinical guidelines and research evidence. Participants will follow the intervention for a duration of four consecutive weeks.

Dietary Supplement: Mediterranean Diet

Care-as-usual (CAU) group

NO INTERVENTION

Participants in the CAU group will be instructed to maintain their usual dietary habits throughout the study period and will not receive any specially prepared Mediterranean diet from the research team. In addition, they will have access to care based on their needs and preferences, such as pharmacological interventions, psychological interventions, and complementary and alternative medicine. An intervention tracking log will be used to monitor the care the participants received to prevent violations of the study protocol. The CAU group will be given lifestyle-based self-help materials after the completion of follow-up assessments.

Interventions

Mediterranean Diet DIETARY_SUPPLEMENT

This group will adhere to the meals (meal delivery, excluding weekends and holidays) prepared by the research team and report their mood and diet quality and adherence using EMA with push notifications four times a day. In addition, photographic food records will also be used to record planned or unplanned meals or snacks. Pre-recorded sessions covering topics such as general dietetic advice, nutrition education on the Mediterranean diet and food components, SMART goal setting will be provided to the participants before the initiation of the MediDiet intervention. Moreover, a brief weekly phone call will be conducted to assess participant adherence, provide encouragement, and address any issues or challenges that may arise.

Mediterranean diet (MediDiet) group

Eligibility Criteria

• Age: 18 Years - 65 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Hong Kong residents aged 18-65 years;
• Able to read Chinese and type in Chinese or English;
• Have a Patient Health Questionnaire-9 (PHQ-9) score of 10 or higher, indicating at least a moderate level of depressive symptoms;
• Meet the Diagnostic and Statistical Manual of Mental Disorders (DSM) diagnostic criteria for current MDD according to the Mini International Neuropsychiatric Interview (MINI);
• Have a Mediterranean Diet Index (KIDMED 2.0) score less than 3, indicating very-low-quality diet;
• Possess an Internet-enabled iOS- or Android-operated mobile device; and
• Willing to provide informed consent and comply with the trial protocol.

You may not qualify if:

• The presence of other current psychiatric disorders as assessed by the MINI (bipolar disorder, posttraumatic stress disorder, personality disorders, eating disorders, psychotic disorders, or substance abuse disorder);
• Have a medical condition or neurocognitive disorder that may prevent dietary changes as recommended by physicians or dietitians;
• Current serious suicidal risk (non-fleeting intent or plan) as assessed by a PHQ-9 Item 9 score \>2 (referral information to professional mental health services will be provided);
• Involvement in dietary changes (self-initiated/supervised by professionals) in the past 2 weeks;
• Involvement in any psychological treatment specifically for depression in the past 6 months;
• A change in medication within 2 weeks prior to the baseline assessment/during the study;
• Pregnancy and hospitalization;
• Current participation in any other trial(s); and
• Unwilling to change their diet if being allocated to the MediDiet group or food allergies or intolerances preventing diet adherence (specifically allergies to seafood, soy, nuts, yogurt, or dairy products).

Sponsors & Collaborators

• Chinese University of Hong Kong: lead

Study Sites (1)

The Chinese University of Hong Kong

Shatin, Hong Kong

Location

MeSH Terms

Conditions

Depression

Interventions

Diet, Mediterranean

Condition Hierarchy (Ancestors)

Behavioral Symptoms; Behavior

Intervention Hierarchy (Ancestors)

Diet, Plant-Based; Diet Therapy; Nutrition Therapy; Therapeutics; Diet; Nutritional Physiological Phenomena; Diet, Food, and Nutrition; Physiological Phenomena

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: OUTCOMES ASSESSOR
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Associate Professor

Study Record Dates

• First Submitted: February 24, 2026
• First Posted: March 2, 2026
• Study Start: March 1, 2026
• Primary Completion (Estimated): February 28, 2027
• Study Completion (Estimated): June 30, 2027
• Last Updated: March 3, 2026

Record last verified: 2026-02

Locations

HK (1)