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Trial registered on ANZCTR


Registration number
ACTRN12621000311853
Ethics application status
Approved
Date submitted
15/02/2021
Date registered
19/03/2021
Date last updated
19/03/2021
Date data sharing statement initially provided
19/03/2021
Type of registration
Retrospectively registered

Titles & IDs
Public title
Kawakawa tea and its effect on glucose absorption in healthy human volunteers
Scientific title
Impact of acute kawakawa tea ingestion on postprandial glucose metabolism in healthy human volunteers
Secondary ID [1] 303454 0
None
Universal Trial Number (UTN)
U1111-1261-6413
Trial acronym
TOAST
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Type 2 Diabetes Mellitus 320763 0
Cardiovascular disease 321093 0
Condition category
Condition code
Metabolic and Endocrine 318592 318592 0 0
Diabetes
Cardiovascular 318894 318894 0 0
Other cardiovascular diseases

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
This study will examine the postprandial glycaemic response after an acute (single) ingestion of either water or kawakawa tea (4g per 250ml of hot water). As previously reported (1), the postprandial state lasts for approximately 4-5 h post-meal period. Participants under the supervision of the clinical coordinator will complete a screening assessment and, if eligible for entry into the trial, will be required in fasted condition to consume either a kawakawa tea infusion (4g per 250ml of hot water) or only hot water within 10 minutes based on their randomisation schedule. Following the intervention, a high glycaemic breakfast containing two slices of white bread, along with 15g of fruit jam and 250ml of rice milk, will be provided after 30 minutes, and participants will be asked to finish within 10 minutes. Blood will be sampled at regular intervals following their visit in fasting state at 0 min and then postprandial following tea or hot water at 30, 45, 60, 90, 120, 180 mins from a cannula inserted into an arm vein. Urine samples will be collected in a fasting state at 0 min, and then 0-4hrs urine will be collected postprandial following tea or hot water consumption. Since this is a two-arm, two-way cross over study, the participants will be required to come again for the intervention after a washout period of at least 48hrs.

References
1. Monnier L, Colette C. Target for glycemic control: concentrating on glucose. Vol. 32 Suppl 2, Diabetes care. 2009.
Intervention code [1] 319747 0
Prevention
Intervention code [2] 319986 0
Treatment: Other
Comparator / control treatment
Hot water-(250ml)
Control group
Active

Outcomes
Primary outcome [1] 326551 0
To examine the effects of kawakawa tea intake prior to consumption of high glycaemic meal on postprandial plasma glucose metabolism in healthy individuals
Timepoint [1] 326551 0
Blood samples collected at fasting and then after the intervention at 30, 45, 60, 90, 120, and 180 mins will be utilised to measure the biochemical parameters of glucose absorption using an Autoanalyser.
Secondary outcome [1] 391845 0
To measure the impact of kawakawa tea ingestion on the inflammatory cytokines such as IL-6, IL-1, TNF-ALPHA, NF-Kb and other cytokines that are part of different inflammatory pathways, using PBMC gene expression.
Timepoint [1] 391845 0
Blood samples collected at fasting and then after the intervention at 30, 45, 60, 90, 120, and 180 mins will be analysed for changes in gene and microRNA expression.
Secondary outcome [2] 391846 0
To measure the impact of kawakawa tea ingestion on plasma insulin,
Timepoint [2] 391846 0
Blood samples collected at fasting and then after the intervention at 30, 45, 60, 90, 120, and 180 mins will be analysed for changes in these biochemical measures using Roche Cobas e411 by electro-chemiluminescence immunoassay.
Secondary outcome [3] 391848 0
To measure the impact of kawakawa tea ingestion on blood lipids including Cholesterol (Total, High-density lipoprotein cholesterol, and low-density lipoprotein cholesterol (LDL-C) and triglycerides.
Timepoint [3] 391848 0
Blood samples collected at fasting and then after the intervention at 30, 45, 60, 90, 120, and 180 mins will be analysed by Roche Cobas c311 autoanalyser by enzymatic colorimetric assay
Secondary outcome [4] 392838 0
To measure the impact of kawakawa tea ingestion on metabolomic changes in the Urine samples
Timepoint [4] 392838 0
Both fasting urine and samples collected post-intervention at 60, 120 and 180 minutes will be analysed using LC-MS.

Eligibility
Key inclusion criteria
• Gender: both males and females. To control for menstruation cycle variation in results, female participants would be required to come in the same phase of their cycle for both the intervention visits.
• Age: 18-45 yr.
• BMI: 18-25 kg/m2
• Non-smokers
• Self-reported not consuming dietary supplements
• No medical conditions
Minimum age
18 Years
Maximum age
45 Years
Sex
Both males and females
Can healthy volunteers participate?
Yes
Key exclusion criteria
Participants will be excluded from participation if they:
• Are taking dietary supplements or herbal remedies which may affect the study outcome
• Are allergic to pepper, nutmeg or similar spices
• Are diagnosed with gastrointestinal disease (i.e. celiac, Crohn’s, colitis, etc.) or pre-existing metabolic disease
• Are currently taking medications expected to interfere with normal digestive or metabolic processes including proton pump inhibitors, laxatives, etc.
• Have used antibiotics within the previous one month or were on long-term antibiotic therapy.
•Have a medical history precluding a healthy state: a history of myocardial infarction, angina, stroke, cancer or pre-existing diabetes.

Study design
Purpose of the study
Prevention
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Participants will be randomised to receive the intervention or the control as the first in a crossover sequence using computer-generated sequences.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
The allocation sequence will be set up through a web-based secure database. Sequences will not be accessible to the research team prior to allocation.
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?



Intervention assignment
Crossover
Other design features
Randomised, Open-label, Two-arm, Two-period crossover trial
Phase
Not Applicable
Type of endpoint/s
Efficacy
Statistical methods / analysis
Differences in the primary endpoints will be compared between treatment groups using Repeated measure ANOVA or non-parametric tests where appropriate and followed-up with posthoc tests. The relationship between secondary end-points will be assessed using multiple regression analysis.

Recruitment
Recruitment status
Recruiting
Date of first participant enrolment
Anticipated
Actual
15/03/2021
Date of last participant enrolment
Anticipated
1/06/2021
Actual
Date of last data collection
Anticipated
30/09/2021
Actual
Sample size
Target
30
Accrual to date
2
Final
Recruitment outside Australia
Country [1] 23465 0
New Zealand
State/province [1] 23465 0
Auckland

Funding & Sponsors
Funding source category [1] 307872 0
University
Name [1] 307872 0
Liggins Institute, The University of Auckland
Country [1] 307872 0
New Zealand
Primary sponsor type
University
Name
Liggins Institute, The University of Auckland
Address
85 Park Road, Grafton, Auckland 1023.
Country
New Zealand
Secondary sponsor category [1] 308581 0
None
Name [1] 308581 0
None
Address [1] 308581 0
None
Country [1] 308581 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 307874 0
Southern Health and Disability Ethics Committee
Ethics committee address [1] 307874 0
Ministry of Health
Health and Disability Ethics Committees
133 Molesworth Street, Thorndon
Wellington 6011
Ethics committee country [1] 307874 0
New Zealand
Date submitted for ethics approval [1] 307874 0
23/11/2020
Approval date [1] 307874 0
12/02/2021
Ethics approval number [1] 307874 0
20/STH/236

Summary
Brief summary
Kawakawa (Piper excelsum) is endemic to New Zealand, where it is widely used for food, therapeutic and traditional ceremonial purposes by Maori. Kawakawa leaves and fruits are reported to contain various active compounds including phenylpropanoids: myristicin, elemicin, piperine; lignans: diayangambin; and amides: piperchabamide, which are shown to possess therapeutic properties and are utilised for a wide range of health conditions not only limited to skin diseases but for the treatment of genitourinary, gastrointestinal as well as respiratory diseases.

Despite the traditional use of kawakawa and its use in commercial products, no studies have been conducted to examine whether kawakawa would impact postprandial glucose metabolism, an important factor responsible for the development of type 2 diabetes (T2DM) and cardiovascular disease (CVDs). Therefore, we aim to examine the effects of kawakawa tea ingestion on postprandial glucose flux using a human randomized controlled intervention
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 108774 0
Prof Richard Mithen
Address 108774 0
Liggins Institute
University of Auckland
85 Park Road
Grafton
Auckland 1023
Country 108774 0
New Zealand
Phone 108774 0
+64 27 201 7675
Fax 108774 0
Email 108774 0
[email protected]
Contact person for public queries
Name 108775 0
Richard Mithen
Address 108775 0
Liggins Institute
University of Auckland
85 Park Road
Grafton
Auckland 1023
Country 108775 0
New Zealand
Phone 108775 0
+64 27 201 7675
Fax 108775 0
Email 108775 0
[email protected]
Contact person for scientific queries
Name 108776 0
Farha Ramzan
Address 108776 0
Liggins Institute
University of Auckland
85 Park Road
Grafton
Auckland 1023
Country 108776 0
New Zealand
Phone 108776 0
+64224505345
Fax 108776 0
Email 108776 0
[email protected]

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
Yes
What data in particular will be shared?
All of the Individual participant data (including data dictionaries) collected during the trial will be available after de-identification, along with the study protocol.
When will data be available (start and end dates)?
Data will be available beginning 3 months following the first publication of study results and ending 36 months following publication.
Available to whom?
Data will be available to investigators who provide a methodologically sound proposal approved by the Study Steering Committee, for use to achieve the aims in the approved proposal. Proposals should be directed to the principal investigator. To gain access, requests will need to sign a data access agreement.
Available for what types of analyses?
For use to achieve the aims in an approved proposal.
How or where can data be obtained?
Proposals should be directed to the principal investigator ([email protected]). To gain access, requests will need to sign a data access agreement.


What supporting documents are/will be available?




Results publications and other study-related documents

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

Documents added automatically
SourceTitleYear of PublicationDOI
Dimensions AIAcute Effects of Kawakawa (Piper excelsum) Intake on Postprandial Glycemic and Insulinaemic Response in a Healthy Population2022https://doi.org/10.3390/nu14081638
N.B. These documents automatically identified may not have been verified by the study sponsor.