This study aims to explore the efficacy and safety of a synbiotic formula (MQU10) in improving mood and well-being in adults with mild to moderate depressive symptoms.

Major depression disorder (MDD) affects up to 20% of the population. In Hong Kong, one in seven suffered from mental health disorders with depressive disorder being one of the most frequent diagnoses. Depression is characterized by persistently low mood and loss of interest, possibly resulting from multifactorial factors including brain chemical abnormalities, genetics, stress, trauma and medical conditions. Current treatments for depression mainly include medication that alters neurotransmission in the brain and cognitive behavioural therapy to change cognitive distortions and their associated behaviours. However, there are side effects associated with the use of antidepressant medications as well as perceived stigma in receiving antidepressants and the uptake and accessibility of psychotherapy is extremely low. Thus, alternative therapeutic options are therefore needed to manage depression and its associated symptoms.

Emerging evidence suggests the important role of gut microbiota and gut-brain axis in mood regulation. In particular, there is high comorbidity among individuals with depression and gastrointestinal conditions such as irritable bowel syndrome and inflammatory bowel disease. There is also evidence suggesting that gut microbiota could produce metabolites and compounds with neuroactive and immunomodulatory properties. Previous studies have also supported the association between the dysbiosis of gut microbiota and affective disorders. Clinical trials on the use of microbiome-based therapeutics showed some efficacy in improving depression and insomnia. Gut microbiota modulation could be a novel therapeutic strategy for improving mood problems.

This pilot, single-arm study aims to explore the efficacy and safety of a synbiotic formula (MQU10), which is composed of food-grade probiotic strains and prebiotic compounds, in improving mood and well-being in adults with mild to moderate depressive symptoms.

Inclusion Criteria:

• Individuals aged 18 or above
• Patient Health Questionnaire-9 (PHQ-9) score between 5 to 14
• Literate and can complete the self-report questionnaires
• Able to understand the consent and sign the informed consent form

Exclusion Criteria:

• Current diagnosis of substance abuse or dependence;
• A current or past history of bipolar disorder, manic or hypomanic episodes, schizophrenia, personality disorder, posttraumatic stress disorder (PTSD), intellectual disability, neurodegenerative disorders (e. g, Parkinson's disease) or organic mental disorder
• Requiring immediate psychiatric care (e. g, imminently suicidal subjects) or have attempted suicide in the past 3 months
• Use of antipsychotics, antidepressants or sedatives, unless on a stable dose in the last 4 weeks
• History of severe organ failure, renal failure on dialysis, HIV infection
• Active malignancy within 5 years
• History of major surgery on the gastrointestinal tract, except cholecystectomy and appendectomy in the past 5 years
• Night shift work
• History of antibiotic use within 4 weeks
• History of allergy to probiotics or lactose leading to a severe allergic reaction
• Known pregnancy or lactating