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Trial registered on ANZCTR


Registration number
ACTRN12618000912280p
Ethics application status
Submitted, not yet approved
Date submitted
14/05/2018
Date registered
30/05/2018
Date last updated
30/05/2018
Type of registration
Prospectively registered

Titles & IDs
Public title
Evaluating the effect of exercise and kiwifruit on blood glucose regulation
Scientific title
Evaluating the effect of exercise and partial kiwifruit exchange of high glycaemic index (GI) carbohydrate on blood glucose regulation in healthy individuals
Secondary ID [1] 294828 0
None
Universal Trial Number (UTN)
U1111-1209-1875
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Type II Diabetes 307768 0
Condition category
Condition code
Metabolic and Endocrine 306813 306813 0 0
Normal metabolism and endocrine development and function

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
This is a single-blind, placebo controlled parallel design intervention study that will allow us to evaluate whether exercise has any effect in modifying the reduction in glycaemic response (when consumed with a high GI drink) conferred by kiwifruit. Prospective participants will be asked to attend a familiarisation session where they will meet with the study’s principal investigator (research scientist, PhD). During the session, the principal investigator will explain the study’s objectives and what is required from them as a volunteer. Each participant will be asked to complete a health screening and a Baecke habitual physical activity questionnaires which will be assessed against the study’s exclusion/inclusion criteria. They will also be asked to sign a consent form to confirm their permission to proceed as a volunteer in this study. Participants will be introduced to the Rating of Perceived Exertion (RPE) scale that they will be responding to during the trial days. Finally, participants will be asked to perform an exhaustive cycle exercise test (under the guidance of the principal investigator) to estimate their maximal aerobic capacity that will allow us to estimate the workload they will need to perform on the trial days. Measuring each participant’s aerobic capacity allows us to ensure that participants are exercising at the same intensity relative to their fitness as participant’s fitness levels will vary.

All recruited participants will be required to attend an initial Non-Exercise Trial Day where their baseline resting glycaemic response after consuming a glucose drink will be characterised. Participants will arrive on the morning of their trial day in a fasted state (no food for 12 hours) where they will be given a sugar drink (50 g glucose dissolved in 250 mL water) to consume quickly (within two minutes). Their blood glucose will be subsequently measured from finger prick samples at regular intervals for up to 2 hours after consuming their glucose drink.

To assess if the exercise has any effect in modifying the modulatory effect of kiwifruit on the glycaemic response, recruited participants will be required to complete two trial days with an exercise (Exercise Trial Days 1 and 2). Participants will be evenly randomly allocated into two treatment groups: (1) kiwifruit and (2) placebo (kiwifruit sugar) group. Exercise Trial Day 1 will involve determining participant’s post-exercise glycaemic response after consuming a glucose drink following a 10 min exercise cycle bout. On Exercise Trial Day 2, the post-exercise glycaemic response after consuming either a kiwifruit or placebo drink (depending on which treatment group a participant has been allocated to) will be assessed following a 10 minute exercise. By implementing this trial design, we will be able to compare how consuming kiwifruit (or kiwifruit sugar) may further affect changes in the glycaemic response induced by exercise and whether these changes (in any) differ between the two treatment groups. On the morning of these exercise trial days, participants will arrive on-site in a fasted state as they did previously. They will then be required to complete a 10 minute exercise cycle at an intensity corresponding to 75% their maximal aerobic intensity. The principal investigator will be present at this time to monitor the participant’s adherence to the exercise and give verbal encouragement to ensure that they perform the exercise to the best of their ability. Five minutes after the completion of their exercise, participants will be required to consume the glucose drink or one of the treatment intervention drinks (i.e. kiwifruit or placebo). The kiwifruit intervention drink will compose of 200 g kiwifruit with added glucose to total of 50 g available carbohydrate made up to a volume of 250 mL with water.

In summary, all participants will take part in three trial days which will involve a Non-exercise Trail Day and two Exercise trial days:
Non-exercise Trial Day: All participants’ (n=30) resting glycaemic response after consuming a drink containing 50 g glucose will be assessed.
Exercise Trial Day 1: All participants’ (n=30) post-exercise glycaemic response after a 10 minute cycle exercise followed by consuming a drink containing 50 g glucose will be assessed.
Exercise Trial Day 2: Participants’ glycaemic response after a 10 minute cycle followed by consuming their allocated nutritional intervention – kiwifruit (n=15) or kiwifruit sugar (n=15) will be assessed.

As participant’s post-exercise response will be assessed for only one of the nutritional treatment interventions, this is a parallel study. Trial days will be separated by at least 1 week to avoid any training effect from performing the exercise cycle. No maximum amount of time between exercise trial days is set, but we aim to run our participants through all trial days within 3 months after recruitment.
Intervention code [1] 301140 0
Treatment: Other
Comparator / control treatment
The placebo drink will contain fructose, glucose and sucrose equal in amount to that present in 200 g kiwifruit, plus added glucose so that the total of available carbohydrate in the drink is 50 g. The sugars will be dissolved in 250 mL water. All treatment drinks will be served in opaque food grade drink bottles so that the trial investigators are blinded to which treatment is being administered.
Control group
Placebo

Outcomes
Primary outcome [1] 305819 0
Blood glucose concentration - blood glucose will be measured using a "point-of-test" biosensor from blood drawn from a finger prick.
Timepoint [1] 305819 0
On the first trial day where participant's baseline glycaemic will be characterised, blood glucose will be measured before consuming the glucose drink and at 15, 30, 45, 60, 90 and 120 minutes after consuming the glucose drink. On the exercise trail days, blood glucose will be measured before exercise, immediately after exercise and 15, 30, 45, 60, 90 and 120 minutes after consuming the intervention drink. Data gathered from all these timepoints will be used to measure glycaemic response including glycaemic peak and area under the curve after consuming the sugar or treatment drinks.
Primary outcome [2] 305820 0
Insulin, a biomarker of glucose regulation, will be measured in blood plasma using a commercial enzyme-linked immunosorbent assay (ELISA) kit

Timepoint [2] 305820 0
On all exercise trial days plasma insulin concentrations will be measured from venous bloods samples collected before exercise, immediately after exercise and 30, 60, 90 and 120 minutes after consuming the glucose or treatment drink. Data gathered from all these timepoints will be used to characterise insulin production for up to 2 hours following glucose or treatment drink intake after a bout of exercise.
Primary outcome [3] 305875 0
Glucagon, a biomarker of glucose regulation, will be measured in blood plasma using a commercial ELISA kit.
Timepoint [3] 305875 0
On all exercise trial days plasma glucagon concentrations will be measured from venous bloods samples collected before exercise, immediately after exercise and 30, 60, 90 and 120 minutes after consuming the glucose or treatment drink. Data gathered from all these timepoints will be used to characterise glucagon production for up to 2 hours following glucose or treatment drink intake after a bout of exercise.
Secondary outcome [1] 346659 0
Oxidative capacity, a measure of oxidative stress, will be measured in plasma using a validated fluorescent assay developed in-house.
Timepoint [1] 346659 0
On all exercise days oxidative capacity will be measured from venous blood samples collected before exercise, immediately after exercise and 30, 60, 90 and 120 minutes after consuming the treatment drink.
Secondary outcome [2] 346660 0
Malondialdehyde concentration, a biomarker of oxidative stress, will be measured in blood plasma using a validated high performance liquid chromatography protocol developed in our laboratory.
Timepoint [2] 346660 0
On all exercise days oxidative capacity will be measured from venous blood samples collected before exercise, immediately after exercise and 30, 60, 90 and 120 minutes after consuming the treatment drink.
Secondary outcome [3] 346867 0
Composite measures of cardiopulmonary performance during exercise and recovery (heart rate and oxygen/carbon dioxide exchange) will be measured throughout the exhaustive and submaximal cycle exercises during the familiarisation and trial days, respectively.
Timepoint [3] 346867 0
Heart rate and oxygen/carbon dioxide exchange will be measured through the duration of the exhaustive cycle exercise on the familiarisation day to determine the maximal aerobic capacity of participants. These parameters will also be measured through the duration of the 10 minute submaximal cycle on the exercise trial days. These parameters will be continuously measured up to 30 mins after the 10 minute submaximal exercise to characterise the recovery of the participants. Heart rate will be measured using a chest-worn heart rate monitor and oxygen/carbon dioxide exchange will be measured using a breath-by-breath cardiopulmonary exercise testing (CPET) machine.

Eligibility
Key inclusion criteria
Healthy untrained individuals who are not involved in any strenuous exercise training regime (determined from Baecke habitual activity and health questionnaires) and can complete the physical requirements of the exercises (determined on the familiarisation day) will be able to take part in this study. Participants will be required to complete a health questionnaire and provide written consent to take part in this study.
Minimum age
18 Years
Maximum age
55 Years
Gender
Both males and females
Can healthy volunteers participate?
Yes
Key exclusion criteria
Individuals unable or unwilling to provide informed consent or comply to the study procedures will be excluded from this study. Other exclusion criteria include (i) known hypersensitivity or intolerance to kiwifruit or kiwifruit-derived products, (ii) have health conditions that impair their ability to perform exercises or may be aggravated by the exercises in this study (e.g. injury, hernia, back/joint pain, cardiovascular and breathing problems), (iii) have a Sports Index score of 4.5 or greater as assessed by a Baecke questionnaire, (iv) or are unable to perform the exercises to the standard required by the trial coordinator during the familiarisation session. Individuals will also be excluded from participating in this study if they are pregnant, planning to get pregnant or have any of the following conditions: (i) Type I or II diabetes or are pre-diabetic, (ii) are diagnosed with a blood borne disease (e.g. hepatitis), (iii) diagnosed with high/low blood pressure, (iv) have had a recent bacterial or viral illness or (v) are taking medication that affects the properties of blood (e.g. blood clotting).

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)
The random allocation of participants into the two treatment groups will be undertaken by a fellow scientist not involved in this study using a computer randomisation function. All recruited participants taking part in this study will then be allocated a random participant code (consisting of numerical and alphabetical characters) containing no information on which treatment group participants were allocated to. To conceal the treatment allocation from the study investigators, those preparing and serving the nutritional interventions to the participants will not be involved in any other component of the study. Further, the nutrition interventions will be served to participants in a separate room away from study investigators administering the exercise interventions. Drinks will be served in opaque containers as a measure to visually conceal which treatment was administered to the volunteers from the exercise study investigators.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
This is a single-blind, placebo controlled, parallel design intervention study. Participants will be randomly allocated into two nutritional intervention groups: Kiwifruit or Placebo (kiwifruit sugar). The computerised randomisation of participant treatment allocation for each participant will be undertaken by a fellow scientist not involved in this study. Participant treatment allocation is held and concealed until completion of the trial and analysis of the data is finished. The allocation of nutritional treatment interventions during the exercise trial days will be randomised using the randomisation function in Microsoft Excel.
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?


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
Data will be expressed as mean +/- standard error. Interaction between kiwifruit intake with a high GI sugar and measures of glycaemic response performance will be determined. Interaction between consuming kiwifruit and their effects on exercise performance and measures of oxidative stress will also be determined. Statistical significance for the comparison between Kiwifruit and Placebo groups will be assessed using two-sample t-test. Multiple comparisons will be assessed by two-way ANOVA. Where appropriate, the original data will be transformed to achieve normality and constant variance in the residuals. Statistical significance for all parameters will be set at P < 0.05 with a confidence level of 95%.

Recruitment
Recruitment status
Not yet recruiting
Date of first participant enrolment
Anticipated
Actual
Date of last participant enrolment
Anticipated
Actual
Date of last data collection
Anticipated
Actual
Sample size
Target
Accrual to date
Final
Recruitment outside Australia
Country [1] 10393 0
New Zealand
State/province [1] 10393 0
Manawatu

Funding & Sponsors
Funding source category [1] 299423 0
Government body
Name [1] 299423 0
The New Zealand Institute for Plant & Food Research Ltd.
Address [1] 299423 0
Batchelar Road
Fitzherbert
Palmerston North 4474
Country [1] 299423 0
New Zealand
Primary sponsor type
Individual
Name
Dr. Jocelyn Eason
Address
The New Zealand Institute for Plant & Food Research
Batchelar Road
Fitzherbert
Palmerston North 4474
Country
New Zealand
Secondary sponsor category [1] 298744 0
None
Name [1] 298744 0
Address [1] 298744 0
Country [1] 298744 0

Ethics approval
Ethics application status
Submitted, not yet approved
Ethics committee name [1] 300324 0
Health and Disability Ethics Committees
Ethics committee address [1] 300324 0
Ministry of Health
133 Molesworth Street
PO Box 5013
Wellington 6011
Ethics committee country [1] 300324 0
New Zealand
Date submitted for ethics approval [1] 300324 0
07/05/2018
Approval date [1] 300324 0
Ethics approval number [1] 300324 0

Summary
Brief summary
Clinical studies conducted at Plant & Food Research Ltd. have demonstrated that equal carbohydrate partial substitution (carbohydrate exchange) of a high glycaemic index (GI) food with kiwifruit significantly reduced the glycaemic response, and that the reduction was greater than could be explained by simple carbohydrate exchange, implying the action of additional factors. Although the mechanisms driving the effect of kiwifruit consumption on blood glucose levels are unclear, it may involve kiwifruit modulating the delivery of glucose to the liver, muscle and/or brain.

In addition, preliminary research by Plant & Food Research show that the glycaemic response is reduced when glucose is consumed before and immediately after a bout high intensity exercise. In this study, we aim to determine whether a short high intensity exercise (cycle) further modulates the ability of kiwifruit to moderate blood glucose levels after consuming a high GI sugar drink.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 83298 0
Dr Dominic Lomiwes
Address 83298 0
The New Zealand Institute for Plant & Food Research Ltd.
Batchelar Road
Private Bag 11600
Palmerston North 4442
Country 83298 0
New Zealand
Phone 83298 0
+64 6 355 6113
Fax 83298 0
+64 6 351 7050
Email 83298 0
dominic.lomiwes@plantandfood.co.nz
Contact person for public queries
Name 83299 0
Dr Roger Hurst
Address 83299 0
The New Zealand Institute for Plant & Food Research Ltd.
Batchelar Road
Private Bag 11600
Palmerston North 4442
Country 83299 0
New Zealand
Phone 83299 0
+64 6 953 7677
Fax 83299 0
+64 6 351 7050
Email 83299 0
roger.hurst@plantandfood.co.nz
Contact person for scientific queries
Name 83300 0
Dr Dominic Lomiwes
Address 83300 0
The New Zealand Institute for Plant & Food Research Ltd.
Batchelar Road
Private Bag 11600
Palmerston North 4442
Country 83300 0
New Zealand
Phone 83300 0
+64 6 355 6113
Fax 83300 0
+64 6 351 7050
Email 83300 0
dominic.lomiwes@plantandfood.co.nz

No information has been provided regarding IPD availability
Summary results
No Results