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Trial registered on ANZCTR


Registration number
ACTRN12622000629730
Ethics application status
Approved
Date submitted
22/04/2022
Date registered
28/04/2022
Date last updated
1/11/2023
Date data sharing statement initially provided
28/04/2022
Date results information initially provided
1/11/2023
Type of registration
Prospectively registered

Titles & IDs
Public title
Mamaku effects on blood glucose response
Scientific title
Mamaku pith effects on the postprandial glycaemic response to carbohydrate food in healthy adults
Secondary ID [1] 306942 0
Nil known
Universal Trial Number (UTN)
U1111-1277-5004
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Diabetes 326053 0
Metabolic health 326054 0
Condition category
Condition code
Metabolic and Endocrine 323359 323359 0 0
Diabetes

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
This is a simple study with the primary aim of showing whether or not mamaku pith has the capacity to reduce post prandial glycaemic response to carbohydrate food consumed at the same time, as has been shown for food hydrocolloids with similar properties. Blood glucose response is the primary outcome, and associated insulin response and satiety are secondary outcomes.
This is a randomised single blinded placebo controlled crossover intervention study involving healthy young and middle-aged adult volunteers within the age range 20-60 y. Before taking part in the study they will have read the participant information sheet, provided written consent, and been assessed against the inclusion and exclusion criteria for the study. We aim to recruit 20 volunteers from the general population in Palmerston North. Each participant will ingest each of five meal treatments, with the order of treatments randomised for each individual. Randomization of the treatment order will be carried out by a statistician at Plant & Food Research using random numbers generated in Microsoft excel.
On trial days involving ingestion of test meals the participants will be asked to arrive at the clinic fasted, that is, not having eaten since 10 pm the previous evening, and having had a moderate evening meal before then. The participants will be asked to provide two baseline blood samples and rate their satiety on the visual analogue scale provided. They will then be asked to ingest their test meal within 10 minutes of the baseline blood sampling. Blood samples will be taken by finger prick at 15, 30, 45, 60, 90, 120 and 180 minute from baseline (T = 0). Ratings of appetite sensations over the same period will be made on a visual analogue scale.
The meals (treatments) will be:
1. WeetBix (59.7 g) plus 250 ml water plus blackcurrant flavouring (100 mg blackcurrant flavour + 50 mg maltodextrin).
2. WeetBix (59.7 g) plus dried mamaku pith (5 g) dispersed in 250 ml water just before consuming plus blackcurrant flavouring.
3. WeetBix (59.7 g) plus dried mamaku pith (5 g) dispersed in 250 ml water an hour before consuming plus blackcurrant flavouring.
4. WeetBix (59.7 g) plus undried mamaku pith (10 g) blended with 240 ml water just before serving plus blackcurrant flavouring1.
5. WeetBix (59.7 g) plus guar gum (3 g) dispersed in 250 ml water just before serving plus blackcurrant flavouring.

1 A treatment with Mamaku at this concentration will be included at the request of the Maori research partner as they believe it to be effective, based on Maori experience.

All meals deliver a dose of 40 g of WeetBix available carbohydrate of which about 96% is readily digested starch and 4% sugar.
Participants will consume not more than two of the test meals per week with at least two days between each test meal. Therefore involvement in the trial will last for a minimum of three weeks.

Adherence of the intervention will be by the researchers directly observing the participants during the 3 hours for each session. There will be a wash-out period of 48 hours between each treatment.
Intervention code [1] 323389 0
Lifestyle
Intervention code [2] 323390 0
Prevention
Comparator / control treatment
WeetBix plus 250 ml water plus blackcurrant flavouring plus maltodextrin
Control group
Active

Outcomes
Primary outcome [1] 331105 0
Blood glucose as assessed by finger-prick blood test.
Timepoint [1] 331105 0
Blood glucose testing will be timed from the start of food consumption. It will be done by finger prick sampling of capillary blood at 15 min intervals in the first hour, and then at 30 min intervals until 180 min has elapsed. Samples will be collected at 0 (baseline x 2), 15, 30, 45, 60, 90, 120, 150 and 180 minutes. Blood glucose will be measured immediately using a HemoCue® blood glucose meter.
Primary outcome [2] 331106 0
Measure changes in insulin.
Timepoint [2] 331106 0
Capillary blood sample will be drawn into a Z gel serum Microvette® microtube designed for capillary blood collection, centrifuged and stored at -80°C for later analysis of insulin.
Timepoints: 0, 15, 30, 45, 60, 90, 120, 150 and 180 minutes are relative to the participants post-meal consumption.
Secondary outcome [1] 408749 0
Changes in satiety will also be measured using 'Visual Analogue Scale'.
Timepoint [1] 408749 0
At time 0, 15, 60, 120 and 180 min, post-test meal consumption, appetite will be assessed using a Visual Analogue Scale (VAS). VAS is used for self-reporting appetite in healthy adult.
Secondary outcome [2] 408750 0
Changes in feeling of gut comfort.
Assessment of gut comfort will be on the test days for each treatment. The gut comfort chart is AstraZeneca's validated questionnaire.
Timepoint [2] 408750 0
Daily on test days at time 0, 60, 120 and 180 min after meal consumption.

Eligibility
Key inclusion criteria
• Age: 18-65 years.
• Sex: Any gender.
• BMI between 18 and 35.
• Health: Healthy as gauged by self-assessment and result on the General Health Questionnaire.
• No indication of impaired glucose metabolism as indicated by fasting blood glucose and HbA1c determined on finger-prick samples.
• Agreement: Participant having given written informed consent to comply with the conditions of the trial.
• No allergic reaction to wheat products.
Minimum age
18 Years
Maximum age
65 Years
Sex
Both males and females
Can healthy volunteers participate?
Yes
Key exclusion criteria
• Fasting blood glucose > 5.6 mmol/L and HbA1c > 40 mmol/mol
• Allergic to or intolerant of wheat products.
• Any gastrointestinal disorder.
• Unwilling or unable to provide informed consent or comply with the study procedures.
• Having Type I or II 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 who pass the screening procedure will be allocated the study trial numbers (de-identified). Each participant will receive all treatments in random order. Randomization of the samples and treatments will be completed by a statistician at Plant & Food Research using a computer.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
The order of the diets and treatments for each participant (n = 20) will be determined by computer randomisation of numbers.
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s


Intervention assignment
Crossover
Other design features
Phase
Not Applicable
Type of endpoint/s
Efficacy
Statistical methods / analysis
Groups will be compared in terms of incremental area under the curve for blood glucose response, insulin, and satiety by comparison of treatments.

Recruitment
Recruitment status
Completed
Date of first participant enrolment
Anticipated
4/05/2022
Actual
24/05/2022
Date of last participant enrolment
Anticipated
17/06/2022
Actual
13/07/2022
Date of last data collection
Anticipated
2/09/2022
Actual
26/08/2022
Sample size
Target
20
Accrual to date
Final
16
Recruitment outside Australia
Country [1] 24734 0
New Zealand
State/province [1] 24734 0
Palmerston North

Funding & Sponsors
Funding source category [1] 311261 0
Government body
Name [1] 311261 0
National Science Challenge - High Value Nutrition
Country [1] 311261 0
New Zealand
Primary sponsor type
Government body
Name
National Science Challenge - High Value Nutrition
Address
University of Auckland,
Private Bag 92019,
Auckland 1142
Country
New Zealand
Secondary sponsor category [1] 312618 0
Government body
Name [1] 312618 0
National Science Challenge - High Value Nutrition
Address [1] 312618 0
University of Auckland,
Private Bag 92019,
Auckland 1142
Country [1] 312618 0
New Zealand
Other collaborator category [1] 282271 0
Charities/Societies/Foundations
Name [1] 282271 0
Nga uri o te Ngahere Trust.
Address [1] 282271 0
274 Wainui Raod,
Torere,
Road 1,
Opotiki 3122
Country [1] 282271 0
New Zealand

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 310773 0
The Central Health and Disability Ethics Committee
Ethics committee address [1] 310773 0
Ministry of Health
133 Molesworth Street
PO Box 5013
Wellington
6011
Ethics committee country [1] 310773 0
New Zealand
Date submitted for ethics approval [1] 310773 0
13/04/2022
Approval date [1] 310773 0
17/05/2022
Ethics approval number [1] 310773 0
2022 EXP 12634

Summary
Brief summary
Mamaku (Cyathea medullaris) is a tree fern that grows widely in Aotearoa (New Zealand) and is regarded as a Taonga species. Mamaku contains a gum in its fronds and stem, located largely in the pith. This gum has a unique “shear-thickening” property which means that it, and the pith that contains it, can form highly cohesive dispersions in water-based media, such as the gut contents.
The rheological properties of suspensions of mamaku pith lead to a suppression of physical processes such as mixing and diffusion, which are important in determining the rate of food digestion and absorption from the intestine. A reduced rate of absorption of glucose released during starch digestion has the important effect of lowering the blood glucose response to starchy foods. Hydrocolloids such as guar gum, psyllium husk, and many other gums that also increase the viscosity of gut contents have a well-established capacity to suppress the blood glucose (glycaemic) response to digestible carbohydrates. It is therefore highly probable, but not yet shown, that mamaku pith will be able to reduce the glycaemic response to carbohydrate foods consumed at the same time as the mamaku.
An ability to reduce blood glucose concentrations is an extremely important property. High blood glucose is a defining feature of diabetes and metabolic syndrome, which are global epidemics. It is also responsible for many of the medical disorders associated with diabetes as blood glucose reacts chemically with molecules throughout the body. It also leads to a state of oxidative stress and associated suppression of immunity, so that many secondary disorders arise from chronic and chronically repeated bouts of high blood glucose, such as occur after carbohydrate meals.
Foods and food ingredients that suppress postprandial (after-meal) glycaemic response may, therefore, find a ready market, especially in populations, such as in China, where it has been estimated that almost half the population is glucose intolerant. This is an opportunity for Maori business to use Mamaku, as a Taonga species, to found a business based on the anti-glycaemic properties of mamaku. But first it is necessary to establish that mamaku gum, in the form of mamaku pith, has the ability to suppress glycaemic response to carbohydrate food.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 118810 0
Dr John Monro
Address 118810 0
Plant and Food Research
Food Industry Science Centre
Private Bag 11600
Palmerston North 4442
Country 118810 0
New Zealand
Phone 118810 0
+64 6 3556137
Fax 118810 0
Email 118810 0
John.Monro@plantandfood.co.nz
Contact person for public queries
Name 118811 0
Dr John Monro
Address 118811 0
Plant and Food Research
Food Industry Science Centre
Private Bag 11600
Palmerston North 4442
Country 118811 0
New Zealand
Phone 118811 0
+64 6 3556137
Fax 118811 0
Email 118811 0
John.Monro@plantandfood.co.nz
Contact person for scientific queries
Name 118812 0
Dr John Monro
Address 118812 0
Plant and Food Research
Food Industry Science Centre
Private Bag 11600
Palmerston North 4442
Country 118812 0
New Zealand
Phone 118812 0
+64 6 3556137
Fax 118812 0
Email 118812 0
John.Monro@plantandfood.co.nz

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No
No/undecided IPD sharing reason/comment
No individual data will be shared. The sum of all the data will be used in analyses and used in publications.


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.