Trial Review

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Trial registered on ANZCTR


Registration number
Help: Registration number
ACTRN12626001058369
Ethics application status
Help: Ethics application status
Approved
Date submitted
Help: Date submitted
29/07/2026
Date registered
Help: Date registered
26/08/2026
Date last updated
Help: Date last updated
26/08/2026
Date data sharing statement initially provided
Help: Data sharing statement date
26/08/2026
Type of registration
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Prospectively registered

Titles & IDs
Public title
A randomised, controlled feasibility trial of dairy products for depression symptoms in adolescent girls
Scientific title
A randomised, controlled feasibility trial of dairy products for depression symptoms in adolescent girls
Additional trial identifiers [1] 318047 0
N/A
Universal Trial Number (UTN)
Trial acronym
Related trial records

Health condition
Health condition(s) studied:
Depression 343060 0
Condition category
Condition code
Mental Health 339159 339159 0 0
Depression

Intervention/exposure
Study type
Interventional
Description of the intervention or exposure
Arm 1 - Participants allocated to the intervention yoghurt arm will consume one 90 g tub of yoghurt orally once daily for eight weeks (56 days). The yoghurt contains standard yoghurt starter cultures with added Bifidobacterium animalis subsp. lactis BB-12 and provides approximately 1 × 10^9 colony-forming units of BB-12 per daily serve.

Study products will be supplied by Bega Dairy & Drinks and dispensed to participants and their parent/guardian by authorised ZenZone study staff at approximately Weeks 0, 3, and 6. Participants will consume the product at home and may choose between the available flavours.

Participants will record each day whether they consumed all, some, or none of their allocated study product using the WeGuide application. The research dietitian will review adherence data regularly and provide supportive follow-up where missed or partial serves indicate possible adherence difficulties.
Intervention code [1] 334927 0
Treatment: Other
Description of the comparator or control
Arm 2 – Participants allocated to the comparator yoghurt arm will consume one 100 g tub of yoghurt orally once daily for eight weeks (56 days). The product contains standard yoghurt starter cultures and minimal, non-therapeutic quantities of BB-12. Participants may choose between the available flavours.

Arm 3 – Participants allocated to the comparator milk arm will consume 125 mL, equivalent to half a carton, of ultra-heat-treated low-fat flavoured milk orally once daily for eight weeks (56 days). The milk is non-fermented and does not contain live bacterial cultures. Participants may choose between the available flavours.

Both comparator products will be supplied by Bega Dairy & Drinks and dispensed to participants and their parent/guardian by authorised ZenZone study staff at approximately Weeks 0, 3, and 6. Participants will consume the product at home and may choose between the available flavours.

Participants will record each day whether they consumed all, some, or none of their allocated study product using the WeGuide application. The research dietitian will review adherence data regularly and provide supportive follow-up where missed or partial serves indicate possible adherence difficulties.
Control group
Active

Outcomes
Primary outcome [1] 346600 0
Recruitment feasibility.
Timepoint [1] 346600 0
Cumulative data assessed at the conclusion of the recruitment period.
Primary outcome [2] 346601 0
Enrolment feasibility.
Timepoint [2] 346601 0
Cumulative data assessed at the conclusion of the recruitment period.
Primary outcome [3] 346603 0
Participant retention through completion of the eight-week intervention and final assessment.
Timepoint [3] 346603 0
Week 8 after intervention commencement.
Secondary outcome [1] 466634 0
Primary feasibility outcome: adherence to daily study product consumption.
Timepoint [1] 466634 0
Assessed daily from Intervention Day 1 through Day 56 and summarised at Week 8.
Secondary outcome [2] 466637 0
Primary feasibility outcome: completion of required study data collection.
Timepoint [2] 466637 0
Assessed at each scheduled study assessment from baseline through Week 8 and summarised at Week 8.
Secondary outcome [3] 466640 0
Primary feasibility outcome: protocol compliance.
Timepoint [3] 466640 0
Assessed throughout study participation and cumulatively at completion of the final participant follow-up.
Secondary outcome [4] 466642 0
Primary feasibility outcome: study product safety and tolerability.
Timepoint [4] 466642 0
Assessed throughout the eight-week intervention and at the Week 10 post-intervention follow-up.
Secondary outcome [5] 466643 0
Change in depressive symptom severity.
Timepoint [5] 466643 0
Baseline, Week 4, and Week 8 after intervention commencement.
Secondary outcome [6] 466645 0
Change in sleep quality.
Timepoint [6] 466645 0
Baseline, Week 4, and Week 8 after intervention commencement.
Secondary outcome [7] 466652 0
Change in overall emotional and behavioural difficulties.
Timepoint [7] 466652 0
Baseline, Week 4, and Week 8 after intervention commencement.
Secondary outcome [8] 466654 0
Change in health-related quality of life.
Timepoint [8] 466654 0
Baseline, Week 4, and Week 8 after intervention commencement.
Secondary outcome [9] 466655 0
Change in depression symptoms measured by the DASS-Y.
Timepoint [9] 466655 0
Baseline, Week 4, and Week 8 after intervention commencement.
Secondary outcome [10] 466657 0
Change in anxiety symptoms.
Timepoint [10] 466657 0
Baseline, Week 4, and Week 8 after intervention commencement.
Secondary outcome [11] 466658 0
Change in stress symptoms.
Timepoint [11] 466658 0
Baseline, Week 4, and Week 8 after intervention commencement.
Secondary outcome [12] 466659 0
Change in gastrointestinal symptom severity.
Timepoint [12] 466659 0
Baseline, Week 4, and Week 8 after intervention commencement.
Secondary outcome [13] 466661 0
Change in executive function.
Timepoint [13] 466661 0
Baseline and Week 8 after intervention commencement.
Secondary outcome [14] 466662 0
Change in visual recognition memory.
Timepoint [14] 466662 0
Baseline and Week 8 after intervention commencement.
Secondary outcome [15] 466663 0
Change in emotional processing.
Timepoint [15] 466663 0
Baseline and Week 8 after intervention commencement.
Secondary outcome [16] 466665 0
Change in sustained attention.
Timepoint [16] 466665 0
Baseline and Week 8 after intervention commencement.
Secondary outcome [17] 466671 0
Change in stool form.
Timepoint [17] 466671 0
Baseline, Week 4, and Week 8 after intervention commencement.
Secondary outcome [18] 466672 0
Participant-reported global impression of change.
Timepoint [18] 466672 0
Weeks 2, 4, 6, and 8 after intervention commencement.
Secondary outcome [19] 466673 0
Parent/guardian-reported global impression of change in the participant.
Timepoint [19] 466673 0
Weeks 2, 4, 6, and 8 after intervention commencement.
Secondary outcome [20] 466674 0
Change in faecal microbial alpha diversity.
Timepoint [20] 466674 0
Baseline, Week 4, and Week 8 after intervention commencement.
Secondary outcome [21] 466675 0
Change in faecal microbial beta diversity.
Timepoint [21] 466675 0
Baseline, Week 4, and Week 8 after intervention commencement.
Secondary outcome [22] 466680 0
Change in Bifidobacterium animalis species.
Timepoint [22] 466680 0
Baseline, Week 4, and Week 8 after intervention commencement.
Secondary outcome [23] 466681 0
Change in salivary cortisol.
Timepoint [23] 466681 0
Baseline, Week 4, and Week 8 after intervention commencement.
Secondary outcome [24] 466683 0
Change in salivary melatonin.
Timepoint [24] 466683 0
Baseline, Week 4, and Week 8 after intervention commencement.
Secondary outcome [25] 466684 0
Change in hippocampal structure in participants completing the optional MRI sub-study.
Timepoint [25] 466684 0
Baseline and Week 8 after intervention commencement.
Secondary outcome [26] 466685 0
Change in resting-state functional connectivity in participants completing the optional MRI sub-study.
Timepoint [26] 466685 0
Baseline and Week 8 after intervention commencement.
Secondary outcome [27] 466686 0
Change in left hippocampal neurometabolites in participants completing the optional MRI sub-study.
Timepoint [27] 466686 0
Baseline and Week 8 after intervention commencement.
Secondary outcome [28] 466687 0
Change in participant healthcare service use.
Timepoint [28] 466687 0
Baseline and Week 8 after intervention commencement.
Secondary outcome [29] 466688 0
Participant-reported feasibility of the allocated study product and trial procedures.
Timepoint [29] 466688 0
Week 2 after intervention commencement.
Secondary outcome [30] 466689 0
Parent/guardian-reported feasibility of the allocated study product and trial procedures.
Timepoint [30] 466689 0
Week 2 after intervention commencement.
Secondary outcome [31] 466690 0
Participant-reported acceptability of the allocated study product and trial procedures.
Timepoint [31] 466690 0
Week 2 after intervention commencement.
Secondary outcome [32] 466691 0
Parent/guardian-reported acceptability of the allocated study product and trial procedures.
Timepoint [32] 466691 0
Week 2 after intervention commencement.
Secondary outcome [33] 466692 0
Participant-reported appropriateness of the allocated study product and trial procedures.
Timepoint [33] 466692 0
Week 2 after intervention commencement.
Secondary outcome [34] 466693 0
Parent/guardian-reported appropriateness of the allocated study product and trial procedures.
Timepoint [34] 466693 0
Week 2 after intervention commencement.
Secondary outcome [35] 466694 0
Participant experience of the clinical trial.
Timepoint [35] 466694 0
Week 8 after intervention commencement.

Eligibility
Key inclusion criteria
Participants must meet all of the following criteria to be eligible for enrolment into the ZenZone trial:
• Assigned female at birth.
• Aged 14 years at the time of consent.
• Experiencing elevated depressive symptoms defined as a PHQ-A score equal to or greater than 10 at the time of consent.
• Willing and able to give informed consent prior to study enrolment.
• Able to comply with all study procedures, including attending the study site for in-person study appointments or dairy collection (where required).
• A parent or legal guardian willing and able to provide informed consent for the participant’s involvement and to comply with study procedures, including attendance at in-person study visits where required.
• Access to a compatible device (smartphone, tablet, or computer) capable of downloading and using the WeGuide application, with reliable internet access.
Minimum age
14 Years
Maximum age
14 Years
Sex
Females
Healthy volunteers
No
Key exclusion criteria
Participants will be excluded if they meet any of the following criteria:
• Assigned male at birth.
• High habitual consumption of yoghurt or similar cultured dairy products, defined as exceeding two (2) standard serves per week (approximately 400mL in total) within the four (4) weeks prior to consent, between consent and baseline assessment, or within the four (4) weeks prior to baseline assessment, to minimise baseline exposure to live-culture dairy products across all study arms.
• Known or suspected allergy to dairy products (e.g., history of anaphylaxis, urticaria, angioedema, or respiratory symptoms following dairy exposure), and/or clinically significant or suspected intolerance likely to impair safe consumption of the study products, as determined by the Principal Investigator or their delegate.
• Known or suspected allergy (e.g., history of anaphylaxis, urticaria, angioedema, or respiratory symptoms following dairy exposure), and/or clinically significant or suspected intolerance likely to impair safe consumption of the study products, to other components present in the interventional products as determined by the Principal Investigator or their delegate.
• History of significant gastrointestinal disease or gastrointestinal surgery likely to affect digestion, absorption, or tolerance of dairy products, increase the risk of adverse events, or confound study outcomes, as determined by the Principal Investigator or their delegate.
• Current or recent mental health condition requiring acute or specialised treatment (e.g., current psychotic disorder, bipolar disorder with recent manic or hypomanic episode) occurring within the four (4) weeks prior to baseline assessment, or at any time between consent and baseline assessment, or which, in the opinion of the Principal Investigator or their delegate, may pose a risk to the participant’s safety, increase the risk of adverse events, or confound study outcomes.
• Acute suicidal risk, defined as active suicidal ideation with intent and/or plan, or suicidal behaviour, requiring urgent clinical intervention (e.g., emergency department presentation or inpatient admission), occurring within the four (4) weeks prior to baseline assessment or at any time between consent and baseline assessment, or identified during screening or baseline assessment. Participants identified as meeting this criterion will not be enrolled and will be referred for appropriate clinical care in accordance with the study’s risk escalation protocol.
• Current diagnosis of an eating disorder, or at high risk of an eating disorder, as determined by clinical history or screening measures, due to the food-based nature of the intervention.
• Neurodevelopmental, cognitive/intellectual, or communication condition that, in the opinion of the Principal Investigator or their delegate, would impair the participant’s ability to provide informed consent, comply with study procedures, or safely consume the study products, despite reasonable support from a parent or guardian.
• Current participation in another interventional clinical trial that may interfere with the study intervention or outcomes.
• Any known or suspected active and unstable medical condition, or a disorder that, in the opinion of the Principal Investigator of their delegate, may pose a risk to the participant’s safety or interfere with study participation or data interpretation.
• Current psychological, social, or environmental circumstances that, in the opinion of the Principal Investigator or their delegate, would make participation unsafe, inappropriate, or impracticable, or would be likely to compromise adherence to the protocol or data integrity (e.g., safeguarding concerns, family instability, or inability to reliably attend assessments).
• Commencement, dosage change, or discontinuation of medication for a stable ongoing condition (e.g., antidepressants) within the four (4) weeks prior to consent, or between consent and baseline assessment.
• Use of antibiotics within the four (4) weeks prior to consent, or between consent and baseline assessment.
• Commencement or discontinuation of probiotics, synbiotics, prebiotics, or other supplements intended to impact gut health or the gut microbiome within the four (4) weeks prior to consent, or between consent and baseline assessment.

Study design
Purpose of the study
Treatment
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
The allocation sequence will be generated and maintained by an independent statistician who is not involved in participant recruitment, eligibility assessment, or baseline assessment. Study staff will not have access to upcoming allocations. The participant’s allocation will be released to authorised study staff only after eligibility has been confirmed and all baseline assessments have been completed.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
A computer-generated permuted block randomisation sequence will be prepared by an independent statistician. Participants will be allocated in a 1:1:1 ratio to one of the three trial arms.
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?



The people analysing the results/data
Intervention assignment
Parallel
Other design features
Phase
Not Applicable
Type of endpoint/s
Safety/efficacy
Statistical methods / analysis
As this is a feasibility trial, no formal sample-size calculation was undertaken to detect between-group treatment effects. The target sample of 60 participants, approximately 20 per randomised group, was selected to estimate key feasibility parameters, including recruitment, enrolment, retention, intervention adherence, data-collection completion, protocol compliance, and safety, and to provide preliminary estimates of outcome variability and effect sizes to inform a future fully powered trial. Feasibility indicators will be summarised descriptively and compared with prespecified feasibility targets. Continuous variables will be summarised using means and standard deviations or medians and interquartile ranges, as appropriate, and categorical variables using frequencies and percentages. Secondary repeated-measures outcomes will be analysed using generalised estimating equations with robust standard errors. Models will include treatment group, time, and the treatment-group-by-time interaction. Effect estimates and 95% confidence intervals will be reported, and findings will be interpreted as exploratory rather than as definitive tests of efficacy.

Recruitment
Recruitment status
Not yet recruiting
Date of first participant enrolment
Anticipated
1/09/2026
Actual
Date of last participant enrolment
Anticipated
1/06/2027
Actual
Date of last data collection
Anticipated
31/08/2027
Actual
Sample size
Target
60
Accrual to date
Final
Recruitment in Australia
Recruitment state(s)
VIC

Funding & Sponsors
Funding source category [1] 322603 0
Government body
Name [1] 322603 0
NHMRC Medical Research Future Fund (MRFF) Grant application (#2035774).
Country [1] 322603 0
Australia
Funding source category [2] 322605 0
Commercial sector/Industry
Name [2] 322605 0
Bega Dairy & Drinks (providing study intervention products in-kind, and additional funding for the MRI brain scans - no involvement in protocol design, trial conduct, analysis, or final manuscript)
Country [2] 322605 0
Australia
Primary sponsor type
University
Name
Deakin University
Address
Country
Australia
Secondary sponsor category [1] 325716 0
None
Name [1] 325716 0
Address [1] 325716 0
Country [1] 325716 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 321069 0
The Royal Children’s Hospital Human Research Ethics Committee
Ethics committee address [1] 321069 0
Ethics committee country [1] 321069 0
Australia
Date submitted for ethics approval [1] 321069 0
12/01/2026
Approval date [1] 321069 0
25/03/2026
Ethics approval number [1] 321069 0
HREC/122856/RCHM-2026

Summary
Brief summary
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 152562 0
Dr Amelia McGuinness
Address 152562 0
Health, Education and Research Building (HERB), Level 2, 285 Ryrie Street, Geelong, VIC, 3220
Country 152562 0
Australia
Phone 152562 0
+61 3 5227 2217
Fax 152562 0
Email 152562 0
[email protected]
Contact person for public queries
Name 152563 0
Jacinta McMahon
Address 152563 0
Health, Education and Research Building (HERB), Level 2, 285 Ryrie Street, Geelong, VIC, 3220
Country 152563 0
Australia
Phone 152563 0
+61 3 5227 3362
Fax 152563 0
Email 152563 0
[email protected]
Contact person for scientific queries
Name 152564 0
Dr Amelia McGuinness
Address 152564 0
Health, Education and Research Building (HERB), Level 2, 285 Ryrie Street, Geelong, VIC, 3220
Country 152564 0
Australia
Phone 152564 0
+61 3 5227 2217
Fax 152564 0
Email 152564 0
[email protected]

Data sharing statement
Will the study consider sharing individual participant data?
Yes
Will there be any conditions when requesting access to individual participant data?
Persons/groups eligible to request access:
• Anyone

• Researchers
Conditions for requesting access:
• Yes, conditions apply:
• Requires review on a case-by-case basis by the trial custodian, sponsor or data sharing committee
• Requires a scientifically sound proposal or protocol
• Requires approval by an ethics committee
• Requires a data sharing agreement between data requester and trial custodian or sponsor

• Individual-level data will only be shared where the relevant optional consent has been provided. Fully de-identified datasets may be made publicly available without an individual application. Detailed sequencing data that may contain human DNA will only be shared with approved researchers through controlled-access processes.

What individual participant data might be shared?
• De-identified individual participant data:
• All outcomes data
• Fully de-identified microbiome and other study data with no human DNA may be made openly available. Detailed stool sequencing data that may contain incidental human DNA will be restricted to controlled-access databases.

What types of analyses could be done with individual participant data?
• Systematic reviews and meta-analyses
• Studies exploring new research questions
• Health economic analyses
• Studies testing whether findings can be repeated or confirmed
• Other scientifically and ethically approved future health research consistent with the consent provided.

When can requests for individual participant data be made (start and end dates)?
From:
After publication of main results
To:
No end date
Where can requests to access individual participant data be made, or data be obtained directly?
• Data repository: Fully de-identified microbiome, clinical, survey, biomarker, cognitive, imaging, and other study data may be deposited in appropriate public or restricted-access research repositories. Detailed sequencing data that may contain human DNA will be stored in a controlled-access repository. This trial registry will be updated with the data repositories used at the end of the trial. For more information on where the data is saved, contact the research team.

• Data sharing request system: Requests for controlled-access data will be managed through the relevant repository request process and applicable Deakin University governance review.

• Journal publication or its supplementary materials: Summary results and suitable aggregated or fully de-identified data may be made available with the main study publications or their supplementary materials.

• Email of trial custodian, sponsor or committee: Requests may be directed to the ZenZone Trial team at [email protected] or via the contacts provided in this registration. This will be reviewed by the trial steering committee.

Are there extra considerations when requesting access to individual participant data?
No


What supporting documents are/will be available?

No Supporting Document Provided


Results publications and other study-related documents

Documents added manually
No documents have been uploaded by study researchers.

Documents added automatically
No additional documents have been identified.