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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
Glycaemic index of kiwifruit - a human intervention study
Scientific title
A randomised trial :To determine the glycaemic index for three kiwifruit cultivars in healthy adults.
Secondary ID [1] 298215 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Diabetes 312821 0
Metabolic disorders 312822 0
Condition category
Condition code
Metabolic and Endocrine 311321 311321 0 0

Study type
Description of intervention(s) / exposure
A randomised repeated measures design will be used in which each subject receives all the test foods (each cultivar of kiwifruit) once only. Glucose which will be used as a reference in this trial will be consumed twice by the participants. The order of the diets and treatments will be randomised for each subject. Randomization of the samples and treatments will be carried out by a statistician at Plant & Food Research.
The test foods will be as follows:
1. Glucose 50 g (reference) dissolved in 250 mL water
2. Kiwifruit cultivars A (50 g available carbohydrate)
3. kiwifruit cultivar B (50 g available carbohydrate)
4. kiwifruit cultivar C (50 g available carbohydrate)
5. Glucose 50 g (reference) dissolved in 250 mL water

Foods 1, 2, 3, 4, 5 above contain approximately 50 g of available carbohydrate. The exact available carbohydrate content of all diets will be determined by in vitro digestive analysis prior to calculating the results.
All of the kiwifruit to be used will be peeled, chilled, briefly mashed, thoroughly mixed, divided into 200 g portions and frozen until testing, so that all subjects are tested with identical composites of the three cultivars, and there is no change in ripening over the course of the study. The kiwifruit will be thawed to room temperature immediately before testing. The subjects will be given 200 ml of water to be consumed with all diets.
On each test day the volunteers will be seated and asked to remain so for the duration of the test. They may continue work, if practical to do so, at the testing location. Once each subject is relaxed and comfortable a baseline blood sugar measurement will be taken in duplicate for that day. Each subject will then be given a test food and instructed to consume the whole amount within a ten-minute period. Blood glucose testing will be timed from the start of food consumption by finger prick sampling of capillary blood at 15 min intervals in the first hour and then at 30 min intervals until 120 min has elapsed. Samples will be thus be collected at 0 (baseline x 2), 15, 30, 45, 60, 90, 120 minutes. Two analyses will be made from each blood sample: blood glucose will be measured immediately using a HemoCue® blood glucose meter.
There will be at least 48 hours 'wash out' period between treatments.
A trained research staff will administer the intervention including pricking finger.
Adherence to the intervention - During the study the participants will be required to refrain from eating after 9 pm, and avoid any strenuous physical activity on the night preceding testing. They will be asked to consume a similar evening meal before each of the 5 test days. The participants will be asked on the day of the test if they adhered to the restrictions. If the answer is 'no', then the participant will be asked come back for testing another day after having observed the restrictions.
Intervention code [1] 314462 0
Intervention code [2] 314463 0
Comparator / control treatment
Glucose - 50g available carbohydrate
Control group

Primary outcome [1] 320049 0
To determine the glycaemic index for three kiwifruit cultivars, Blood glucose concentration will be measured immediately using a HemoCue® blood glucose meter.
Timepoint [1] 320049 0
Measure blood glucose concentrations at 0 (baseline x 2), 15, 30, 45, 60, 90 and 120 minutes after a serving 50g available carbohydrate for each cultivar. Then compare the blood glycose response to that of glucose using area under the curve. Washout between session will be least 48-hour.
Secondary outcome [1] 370371 0
Timepoint [1] 370371 0

Key inclusion criteria
• Age: Aged between 21 and 40.
• Sex: Male or female.
• BMI: Volunteers have a body mass index between 18.5 and 25 kg/m2
• Glucose tolerance: No history of diabetes or evidence of glucose intolerance in a preliminary screening test.
• Tolerant to kiwifruit.
• Health: Healthy as gauged by self-assessment and result on the General Health Questionnaire.
• Agreement: Subject having given written informed consent to comply with the conditions of the trial.
Minimum age
21 Years
Maximum age
40 Years
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
• Glucose intolerance: Any history of diabetes or evidence of glucose intolerance in a preliminary test (greater than 6.0mmol/l fasting glucose, International Diabetes Federation recommendation) and HbA1c greater than 40 mmol/mol
• Non-fasting: Having consumed anything apart from water in the twelve hours prior to the test.
• Allergic to kiwifruit
• Pregnant or breastfeeding.
• Intentionally restrict food intake
• Take part in sports at competitive and/or endurance levels

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Each participant will be assigned an identification number, including those who fail the screening procedure by central randomization by computer.

Participants who pass the screening procedure will be allocated numbers after the recruitment process is finished. Therefore, the recruiter was unaware of the treatment order for each individual at time of recruiting. Each participant receives all treatments in random order rather than being allocated to one group. Randomization of the samples and treatments will be completed by a statistician at Plant & Food Research using a computer.

Allocation Not Concealed.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
The order of the diets and treatments for each subject (n=10) will be determined by computer randomisation of numbers
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?

Intervention assignment
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis
Groups will be compared in terms of response amplitude, time 0 baseline and incremental area under the blood glucose response curve by comparison of treatments. A registered statistician at Plant and Foood Research will conduct the statistical analysis.

The participant numbers (n = 10) the minimum number (n=10) specified by the current ISO method (ISO 26642:2010) for determination of glycaemic index and is typical of studies involving comparisons of foods.

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] 21479 0
New Zealand
State/province [1] 21479 0

Funding & Sponsors
Funding source category [1] 302774 0
Commercial sector/Industry
Name [1] 302774 0
Zespri International
Address [1] 302774 0
400 Maunganui Road,
Mt Maunganui,
New Zealand
Country [1] 302774 0
New Zealand
Primary sponsor type
Government body
New Zealand Institute for Plant & Food Research
Private Bag 11600, Palmerston North 4442, New Zealand
New Zealand
Secondary sponsor category [1] 302718 0
Name [1] 302718 0
Address [1] 302718 0
Country [1] 302718 0

Ethics approval
Ethics application status
Ethics committee name [1] 303371 0
Southern Health and Disability Ethics Committee
Ethics committee address [1] 303371 0
Ministry of Health
Health and Disability Ethics Committees
PO Box 5013
Wellington 6140
Ethics committee country [1] 303371 0
New Zealand
Date submitted for ethics approval [1] 303371 0
Approval date [1] 303371 0
Ethics approval number [1] 303371 0

Brief summary
Our research at Plant & Food Research has explored various mechanisms by which kiwifruit could beneficially modulate glycaemia, in both in vitro and human intervention studies. These studies have shown that remnants of kiwifruit in the gut may reduce the rate of diffusion through the gut milieu and the rate of mixing of gut contents, both of which may reduce the rate of carbohydrate digestion in vitro. Furthermore, kiwifruit remnants interacted physically with soluble polysaccharides to greatly increase gut viscosity. In the human gut, all of these effects may reduce the digestion, transfer of digestion products to the gut wall, and absorption from the gut milieu by the brush border, and therefore reduce the rate of glucose loading into the portal blood stream.

Our previous research has shown that green and gold kiwifruit have low glycaemic index which means that a serving of kiwifruit may have a small effect on blood glucose concentrations, compared with a serving of high carbohydrate food such glucose. Zespri has produced some new cultivars of kiwifruit and is keen to test them to see if these have low glycaemic index as well. Consuming foods with low glycaemic index may be beneficial for people with impaired glucose tolerance, such as those with Type 2 diabetes.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 53558 0
Dr John Monro
Address 53558 0
Plant and Food Research
Food Industry Science Centre
Private Bag 116000
Palmerston North 4474
Country 53558 0
New Zealand
Phone 53558 0
+64 6 3556137
Fax 53558 0
Email 53558 0
Contact person for public queries
Name 53559 0
Dr Suman Mishra
Address 53559 0
Plant and Food Research
Food Industry Science Centre
Private Bag 116000
Palmerston North 4474
Country 53559 0
New Zealand
Phone 53559 0
+64 6 3556137
Fax 53559 0
Email 53559 0
Contact person for scientific queries
Name 53560 0
Dr John Monro
Address 53560 0
Plant and Food Research
Food Industry Science Centre
Private Bag 116000
Palmerston North 4474
Country 53560 0
New Zealand
Phone 53560 0
+64 6 3556137
Fax 53560 0
Email 53560 0

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No/undecided IPD sharing reason/comment
What supporting documents are/will be available?
No other documents available
Summary results
No Results