COVID-19 studies are our top priority. For all other trials, there is a 4-week delay in processing a trial submitted/resubmitted to the ANZCTR and additional delays for updates of registered trials. We appreciate your patience.

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been endorsed by the ANZCTR. Before participating in a study, talk to your health care provider and refer to this information for consumers
Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Date data sharing statement initially provided
Type of registration
Prospectively registered

Titles & IDs
Public title
Probiotics for Reduction of Exam Stress in Students Study
Scientific title
Investigating the effect of probiotic supplementation to reduce exam stress in university students.: A randomised, double-blind, placebo controlled trial
Secondary ID [1] 300598 0
Nil known
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Stress 316348 0
Condition category
Condition code
Mental Health 314604 314604 0 0
Studies of normal psychology, cognitive function and behaviour

Study type
Description of intervention(s) / exposure
Students will take one capsule a day from the time that they are enrolled in the study and supplied with the capsules until the day of their exam. The intervention period will be between 8-12 weeks but a minimum of 8 weeks.

Capsules containing the probiotic Lactobacillus rhamnosus HN001 (6×109 colony forming units) manufactured to pharmaceutical grade will be supplied by Fonterra. Placebo capsules identical in appearance and smell to the probiotic contain corn-derived matodextrin. Both probiotic and placebo capsules are lactose free and gluten free. The probiotic L. rhamnosus HN001 (6 X 109 cfu) has been safely used in previous studies conducted in New Zealand.

Adherence will be assessed by supplying participants with more capsules than they need for the trial period. Participants will be asked to report the number of capsules they have reamining when they complete post-intervention questions at the end of the trial period. A text reminder will be sent to participants during the trial period reminding them to take the capsules.
Intervention code [1] 316907 0
Intervention code [2] 316981 0
Treatment: Other
Comparator / control treatment
Identical to intervention group but with placebo capsules containing maltodextran
Control group

Primary outcome [1] 322937 0
A change in perceived stress scale scores between the probiotic supplemented group and placebo group. Stress will be measured using the Perceived Stress Scale (PSS) by Cohen et al.
Timepoint [1] 322937 0
Assessed at 12 weeks post-baseline.
Secondary outcome [1] 380295 0
Change in anxiety levels using the State Trait Anxiety Inventory 6 item version (STAI6) scale.
Timepoint [1] 380295 0
Assessed at 12 weeks post-baseline.

Key inclusion criteria
The New Zealand university system operates on two semesters per year with examinations for a paper being held at the end of a semester. The PRESS Study will recruit 815 students enrolled in either the POPHEALTH 111 paper or the PSYCH 108 & 109 papers taken by first year students.
Minimum age
17 Years
Maximum age
50 Years
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
There are three exclusion criteria for the study. Participants will be excluded if they are:
- Currently taking a regular probiotic supplement
- Currently taking immunosuppressant’s e.g. chemotherapy
- Currently involved in another trial

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Numbered containers. Randomisation is undertaken by Fonterra who will supply capsules for this study. neither the researchers nor the participants will know who has been radndomised to probiotic or placebo.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Fonterra undertake the randomisation of participants and will hold the randomisation schedule. Participants will be sequentially assigned a participant number and will recieve the bottle of capsules with that participant number.
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s
The people administering the treatment/s
The people assessing the outcomes
The people analysing the results/data
Intervention assignment
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis
Generalised linear regression and logistic regression models.

Recruitment status
Not yet recruiting
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment outside Australia
Country [1] 22365 0
New Zealand
State/province [1] 22365 0

Funding & Sponsors
Funding source category [1] 305021 0
Commercial sector/Industry
Name [1] 305021 0
Fonterra Co-operative Ltd.
Address [1] 305021 0
109 Fanshawe Street
Auckland 1010, New Zealand
Country [1] 305021 0
New Zealand
Primary sponsor type
The University of Auckland
Private Bag 92019
Auckland 1142
New Zealand
Secondary sponsor category [1] 305377 0
Name [1] 305377 0
Address [1] 305377 0
Country [1] 305377 0

Ethics approval
Ethics application status
Ethics committee name [1] 305416 0
University of Auckland Human Participants Ethics Commitee
Ethics committee address [1] 305416 0
Private Bag 92019
Auckland 1142
Ethics committee country [1] 305416 0
New Zealand
Date submitted for ethics approval [1] 305416 0
Approval date [1] 305416 0
Ethics approval number [1] 305416 0

Brief summary
Background: University students experience higher levels of stress leading up
to examinations. This study hypothesises that supplementation with probiotics will reduce the stress students experience before examinations. Participating students will be randomly assigned to take either probiotic or placebo capsules for the university semester. Student's stress levels, anxiety and psychological wellbeing will be measured before and after the intervention.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 100306 0
Dr Rebecca Slykerman
Address 100306 0
Department of Psychological Medicine
The University of Auckland
Room 3033
Building 507
22-30 Park Avenue
Grafton 1023
Country 100306 0
New Zealand
Phone 100306 0
+64 99231132
Fax 100306 0
Email 100306 0
Contact person for public queries
Name 100307 0
Dr Rebecca Slykerman
Address 100307 0
Department of Psychological Medicine
The University of Auckland
Room 3033
Building 507
22-30 Park Avenue
Grafton 1023
Country 100307 0
New Zealand
Phone 100307 0
+64 99231132
Fax 100307 0
Email 100307 0
Contact person for scientific queries
Name 100308 0
Dr Rebecca Slykerman
Address 100308 0
Department of Psychological Medicine
The University of Auckland
Room 3033
Building 507
22-30 Park Avenue
Grafton 1023
Country 100308 0
New Zealand
Phone 100308 0
+64 99231132
Fax 100308 0
Email 100308 0

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No/undecided IPD sharing reason/comment
Ethical approval not given for individual level data to be shared.
What supporting documents are/will be available?
Study protocol
Informed consent form
Ethical approval
How or where can supporting documents be obtained?
Type [1] 6980 0
Study protocol
Citation [1] 6980 0
Link [1] 6980 0
Email [1] 6980 0
Other [1] 6980 0
Type [2] 6981 0
Ethical approval
Citation [2] 6981 0
Link [2] 6981 0
Email [2] 6981 0
Other [2] 6981 0
Type [3] 6982 0
Informed consent form
Citation [3] 6982 0
Link [3] 6982 0
Email [3] 6982 0
Other [3] 6982 0
Summary results
No Results