Trial Review

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
Help: Registration number
ACTRN12625001335482
Ethics application status
Help: Ethics application status
Approved
Date submitted
Help: Date submitted
17/11/2025
Date registered
Help: Date registered
1/12/2025
Date last updated
Help: Date last updated
1/12/2025
Date data sharing statement initially provided
Help: Data sharing statement date
1/12/2025
Type of registration
Help: Type of registration
Prospectively registered

Titles & IDs
Public title
Acute Cardiovascular Effects of an L-Theanine and L-Glycine Beverage in Postmenopausal Women at Rest
Scientific title
The Effects of a Single Dose containing L-Theanine and L-Glycine (The-Gly) amino acids on blood pressure, heart rate, heart rate variability, and skin microvascular function in Postmenopausal Women
Additional trial identifiers [1] 315760 0
None
Universal Trial Number (UTN)
U1111-1330-7375
Trial acronym
Related trial records

Health condition
Health condition(s) studied:
Cardiovascular Health 339497 0
Post menopause 339875 0
Condition category
Condition code
Cardiovascular 335740 335740 0 0
Normal development and function of the cardiovascular system
Reproductive Health and Childbirth 335741 335741 0 0
Menstruation and menopause

Intervention/exposure
Study type
Interventional
Description of the intervention or exposure
The study is a randomized, double-blind, placebo-controlled, parallel trial consisting of two visits. The first visit for baseline assessments and the second for the supplementation intervention. At the first visit, participants will fast overnight for 10 hours before capillary blood (~100 µL) is collected to measure cardiometabolic risk biomarkers, including fasting glucose, HbA1c, total cholesterol, triglycerides, and HDL-C. Following blood collection, participants will receive breakfast, and baseline anthropometric measurements (height, weight, waist, and hip circumferences) and physical performance tests (grip strength, gait speed, chair-rise ability, and submaximal exercise test) will be conducted. The second visit, occurring within one week, involves a 15-minute supine rest followed by baseline measurements of resting heart rate (HR), heart rate variability (HRV), blood pressure (BP), and skin microvascular function. The aim of the skin microvascular test is to measure the reactive hyperaemia response, providing insights into vascular reactivity and endothelial function of the microcirculation.
Participants will then consume either the active supplement containing 5 g glycine, 200 mg L-theanine amino acids, 3.3 g sweetener, 10mg watermelon flavour, and 1.5 g citric acid, or a colour, flavour, and Odor matched placebo dissolved in 300 mL of water and consumed within 5 minutes.
Adherence to the intervention was ensured by direct observation. After the supplement or placebo was provided, research team monitored participants as they drank the entire beverage, confirming that the full dose was consumed as intended. Any issues during intake were recorded immediately.
Post-intervention measurements of HR, HRV, BP, and skin microvascular function will be repeated at 60 and 120 minutes. Dietary intake will be assessed using a 24-hour recall for the day prior to the second visit, along with a brief recall of breakfast on the day of supplementation.
Intervention code [1] 332414 0
Treatment: Other
Description of the comparator or control
The control group will receive a placebo supplement which will contain no glycine and L-theanine amino acids. The placebo powder will be matched to the active supplement in terms of colour, flavour, and odour. Participants will be instructed to consume placebo in an identical manner as in the active group.
Placebo intervention : The composition of the placebo comprises 3.3 g of sweetener, 10mg of watermelon flavour, and 1.5 g of citric acid, without the inclusion of glycine or L-theanine.
Control group
Placebo

Outcomes
Primary outcome [1] 343371 0
Skin Microvascular Function
Timepoint [1] 343371 0
Pre intervention (Baseline) and post intervention at 60 minutes and 120 minutes
Primary outcome [2] 343372 0
Heart Rate
Timepoint [2] 343372 0
Pre intervention (Baseline) and post intervention at 60 minutes and 120 minutes
Primary outcome [3] 343373 0
Heart Rate Variability
Timepoint [3] 343373 0
Pre intervention (Baseline) and post intervention at 60 minutes and 120 minutes
Secondary outcome [1] 454267 0
Systolic blood pressure
Timepoint [1] 454267 0
Pre intervention (Baseline), post intervention at 60 minutes and 120 minutes
Secondary outcome [2] 455033 0
Diastolic Blood Pressure
Timepoint [2] 455033 0
Pre intervention (Baseline), post intervention at 60 minutes and 120 minutes

Eligibility
Key inclusion criteria
Female participants aged 45 years and above who have experienced natural menopause. Participants will be in general good health, willing to comply with all the study procedures.
Minimum age
45 Years
Maximum age
No limit
Sex
Females
Healthy volunteers
Yes
Key exclusion criteria
Participants will be excluded from the study if they have experienced menopause due to hysterectomy (surgical), medical conditions, or treatments, and if they are on hormonal replacement therapy.

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)
Participants will be assigned a pre-determined and unique participant code during enrollment which will be non-identifiable. All participants will be randomly allocated either the active or control groups. Method of allocation will be located within a sealed envelope and broken when they study is completed (all participants data) is final. The person randomising the participants will not know the allocation.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Sequence generation will be block randomised 1:1 using an online randomizer tool
(https://www.randomizer.org/).
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
Parallel
Other design features
Phase
Not Applicable
Type of endpoint/s
Efficacy
Statistical methods / analysis

Recruitment
Recruitment status
Not yet recruiting
Date of first participant enrolment
Anticipated
12/01/2026
Actual
Date of last participant enrolment
Anticipated
15/07/2026
Actual
Date of last data collection
Anticipated
1/08/2026
Actual
Sample size
Target
30
Accrual to date
Final
Recruitment in Australia
Recruitment state(s)
ACT,NSW

Funding & Sponsors
Funding source category [1] 320370 0
University
Name [1] 320370 0
University of Canberra
Country [1] 320370 0
Australia
Primary sponsor type
University
Name
University of Canberra
Address
Country
Australia
Secondary sponsor category [1] 322959 0
None
Name [1] 322959 0
Address [1] 322959 0
Country [1] 322959 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 318916 0
University of Canberra Human Research Ethics Committee
Ethics committee address [1] 318916 0
Ethics committee country [1] 318916 0
Australia
Date submitted for ethics approval [1] 318916 0
16/09/2025
Approval date [1] 318916 0
04/11/2025
Ethics approval number [1] 318916 0

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

Contacts
Principal investigator
Name 145658 0
Prof Stuart Semple
Address 145658 0
Faculty of Health, University of Canberra, Building 12, Kirinari St, Bruce ACT, 2617
Country 145658 0
Australia
Phone 145658 0
+61 2 62012855
Fax 145658 0
Email 145658 0
[email protected]
Contact person for public queries
Name 145659 0
Harshini Meegaswatte
Address 145659 0
Faculty of Health, University of Canberra, Building 12, Kirinari St, Bruce ACT, 2617
Country 145659 0
Australia
Phone 145659 0
+61 416590824
Fax 145659 0
Email 145659 0
[email protected]
Contact person for scientific queries
Name 145660 0
Prof Stuart Semple
Address 145660 0
Faculty of Health, University of Canberra, Building 12, Kirinari St, Bruce ACT, 2617
Country 145660 0
Australia
Phone 145660 0
+61 2 62012855
Fax 145660 0
Email 145660 0
[email protected]

Data sharing statement
Will the study consider sharing individual participant data?
No
No IPD sharing reason/comment: Participants have not consented to provide IPD




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.