ANZCTR - Registration

Please note the ANZCTR will be unattended from Friday 20 December 2024 for the holidays. The Registry will re-open on Tuesday 7 January 2025. Submissions and updates will not be processed during that time.

Registering a new trial?

To achieve prospective registration, we recommend submitting your trial for registration at the same time as ethics submission.

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

ACTRN12617000502336

Ethics application status

Approved

Date submitted

28/03/2017

Date registered

6/04/2017

Date last updated

14/03/2018

Type of registration

Prospectively registered

Titles & IDs

Public title

A human intervention trial to test the effect of potatoes on blood glucose concentrations.

Scientific title

Glycaemic potency of potatoes: A randomised, repeated measures, human intervention study in healthy volunteers.

Secondary ID [1]

The New Zealand Institute for Plant and Food Research core funding programme: Project code, P/274067/01.

Universal Trial Number (UTN)

U1111-1194-5541

Trial acronym

Linked study record

Health condition

Health condition(s) or problem(s) studied:

Diabetes

Metabolic disorders

Condition category

Condition code

Metabolic and Endocrine

Diabetes

Metabolic and Endocrine

Metabolic disorders

Intervention/exposure

Study type

Interventional

Description of intervention(s) / exposure

A randomised repeated measures design will be used in which each participant receives all diets once, with the order of the diets randomised for each participant.
The test foods will be as follows:
1. Glucose: 50 g (Reference) dissolved in 180 ml water
2. Sliced and boiled Agria potato (50 g carbohydrate)
3. Sliced and boiled Crop 39 potato (50 g carbohydrate)
Each test food will be tested once in each participant and will have a minimum of a 48 hour wash out period between each treatment.
All test foods will contain 50 g 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 potato to be used will be roughly equal in size. They will be brushed, sliced and portioned to achieve a serving of 50 g carbohydrate. Prior to feeding to the participant the potato slices will be boiled to soften. The participants will be given 200 ml of water to be consumed with all diets.
Volunteers will be asked to fast for 12 h prior to each test day and refrain from extreme physical activity. On each test day the volunteers will be seated and asked to remain so for the duration of the test, they continue work, if practical to do so, at the testing location. Once each participant is relaxed and comfortable a baseline blood sugar measurement will be taken in duplicate for that day. Each participant 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 180 min has elapsed. Samples will be thus be collected at 0 (baseline x 2), 15, 30, 45, 60, 90, 120, 150 and 180 minutes. Two analyses will be made from each blood sample. Blood glucose will be measured immediately using a HemoCue (registered trademark) blood glucose meter. The remaining capillary blood sample will be drawn into a Z gel serum Microvette (registered trademark) microtube designed for capillary blood collection, centrifuged and stored at -80 degrees for later insulin analysis. At 0, 15, 60, 120 and 180 min appetite will be assessed using a questionnaire containing recommended visual analogue scales for self-reported appetite in healthy adults (Charlot, 2013).

Charlot, K. and D. Chapelot, Energy compensation after an aerobic exercise session in high-fat/low-fit and low-fat/high-fit young male subjects. Br J Nutr, 2013. 110(6): p. 1133-42.

Intervention code [1]

Prevention

Intervention code [2]

Lifestyle

Comparator / control treatment

Glucose reference (50 g)

Control group

Active

Outcomes

Primary outcome [1]

To determine the glycaemic potency of two potato varieties: Agria and Crop 39 using blood glucose concentrations.

Timepoint [1]

Measure blood glucose concentrations at 0, 15, 30, 45, 60, 120, 150 and 180 mins after a serving of two potato varieties and a glucose reference (equivalent 50 g carbohydrate). Three test sessions will be conducted over a period of two weeks, with at least a 48 hour wash out between test sessions.

Primary outcome [2]

Determine glycaemic index of two potato varieties: Agria and Crop 39 using blood glucose concentrations.

Timepoint [2]

Secondary outcome [1]

Analyse blood insulin responses following the consumption of two potato varieties: Agria and Crop 39.

Timepoint [1]

Measure blood insulin concentrations at 0, 15, 30, 45, 60, 120, 150 and 180 mins after a serving of two potato varieties and a glucose reference (equivalent 50 g carbohydrate). Three test sessions will be conducted over a period of two weeks, with at least a 48 hour wash out between test sessions.

Secondary outcome [2]

Measure satiety with a visual analogue scale questionaire following consumption of two potato varieties: Agria and Crop 39.

Timepoint [2]

At 0. 15, 60, 120 and 180 min appetite will be assessed using a questionnaire containing recommended visual analogue scales for self-reported appetite in healthy adults. Three test sessions will be conducted over a period of two weeks, with at least a 48 hour wash out between test sessions.

Eligibility

Key inclusion criteria

Age: Aged between 18 and 65.
Sex: Male or female.
Glucose tolerance: No history of diabetes or evidence of glucose intolerance in a preliminary screening test.
BMI: Volunteers have a body mass index between 18 and 30 kg/m2
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

18 Years

Maximum age

65 Years

Sex

Both males and females

Can healthy volunteers participate?

Yes

Key exclusion criteria

Glucose tolerance: Any history of diabetes or evidence of glucose intolerance in a preliminary test (greater than or equal to 6.0mmol/l fasting glucose, International Diabetes Federation recommendation).
Non-fasting: Having consumed anything apart from water in the twelve hours prior to the test.
Allergic or intolerant to potatoes.

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)

Each participants will be assigned an identification number, including those who fail the screening procedure.
Participants who pass the screening procedure will be allocated numbers after the recruitment process is finished. Therefore, the recruiter does not know which treatment the participant will start with.
Each participant receives all treatments in random order rather than being allocated to one group. The order will be determined by computer randomisation.

Methods used to generate the sequence in which subjects will be randomised (sequence generation)

The order of the diets for each subject (n=15-20) will be determined by 15-20 computer randomisations of the numbers 1-3.

Masking / blinding

Open (masking not used)

Who is / are masked / blinded?

Intervention assignment

Crossover

Other design features

Phase

Not Applicable

Type of endpoint/s

Efficacy

Statistical methods / analysis

Groups will be compared in terms of response amplitude, time to baseline and incremental area under the blood glucose response curve by comparison of treatments. A registered statistician at Plant & Food Research will conduct the statistical analysis.
Participant numbers are based on the number specified in the standard protocol for glycaemic index (GI) determination and on a recent trial of the effects of kiwifruit on blood glucose, in which n = 20 was enough to detect significant differences between diets.

Recruitment

Recruitment status

Completed

Date of first participant enrolment

Anticipated

19/06/2017

Actual

19/06/2017

Date of last participant enrolment

Anticipated

31/07/2017

Actual

31/08/2017

Date of last data collection

Anticipated

30/11/2017

Actual

30/11/2017

Sample size

Target

Accrual to date

Final

Recruitment outside Australia

Country [1]

New Zealand

State/province [1]

Manawatu

Funding & Sponsors

Funding source category [1]

Government body

Name [1]

The New Zealand Institute for Plant and Food Research

Address [1]

Private Bag 11600, Palmesrton North, New Zealand, 4442

Country [1]

New Zealand

Primary sponsor type

Government body

Name

The New Zealand Institute for Plant and Food Research

Address

Private Bag 11600, Palmerston North, New Zealand, 4442

Country

New Zealand

Secondary sponsor category [1]

None

Name [1]

Address [1]

Country [1]

Ethics approval

Ethics application status

Approved

Ethics committee name [1]

Health and Disability Ethics commitee

Ethics committee address [1]

Ministry of Health
Health and Disability Ethics Committees
PO Box 5013
Wellington 6140

Ethics committee country [1]

New Zealand

Date submitted for ethics approval [1]

17/05/2017

Approval date [1]

08/06/2017

Ethics approval number [1]

17/NTB/88

Summary

Brief summary

Our research has shown that potatoes vary in glycaemic index (GI). This index is used to rank carbohydrates according to how they affect blood glucose. Low GI foods release glucose slowly into the blood stream, whilst high GI foods release glucose rapidly into the blood steam. High GI foods can contribute to development of metabolic diseases, such as obesity and diabetes. Substituting a high GI potato with a low GI potato offers a valuable alternative for people with impaired glucose tolerance, such as those with higher blood glucose levels after fasting, which suggests the body is not managing glucose well. We would like to test some different varieties of potatoes and their effects on blood glucose and insulin (a hormone that helps remove excess glucose from the blood). 
The primary aim of this study is to determine the effects of two potato varieties on blood glucose concentrations. The two potato varieties used in this trial (Agria and Crop 39), have been selected for possessing a high (Agria) and low (Crop 39) GI when estimated using laboratory techniques. We aim to determine the actual GI of Agria and Crop 39 by feeding the potatoes to participants and measuring blood glucose concentrations. We will also look at the effects of the potatoes on blood Insulin, which is a hormone that helps control the levels of glucose in our blood.
The study is a randomized repeated measures design which means participants will be asked to consume three test foods, one per testing session, in random order. The foods will be: (1) glucose (50 g), (2) Agria potato (about 250 g, sliced and boiled), (3) Crop 39 potato (about 250 g, sliced and boiled). 
Individuals will be chosen to participate in the study if they are within the age bracket (18-65) and considered to be generally healthy. 
During the study participants will be required to refrain from eating after 8 pm (water only), and avoid any strenuous physical activity on the night preceding testing. 
In the morning participants will be asked to rest for 15 mins before 2 baseline blood samples (by finger prick) are taken. Participants will then be given one of the 3 test foods to consume within 10 mins and small blood samples will be taken at 15, 30, 45, 60, 90, 120, 150 and 180 min after consuming the food for measurement of blood glucose and insulin.
Blood sampling involves use of a finger prick device (as used by diabetics at home) which almost painlessly allows a small bead of blood to be massaged from the finger and used to monitor your blood glucose and insulin levels over the three hours after consuming the food. 
During the three hours participants will be able to bring some paperwork to complete in the human clinic facility, and drink a set amount of water if thirsty, but consume no food until after the final blood test. At 0., 15, 60, 120 and 180 mins during the trial participants will be asked to fill out a short questionnaire to assess their hunger.

Trial website

Trial related presentations / publications

Public notes

Contacts

Principal investigator

Name

Dr John Monro

Address

The New Zealand Institute for Plant and Food Research,
Private Bag 11600
Palmerston North
New Zealand
4442

Country

New Zealand

Phone

+6463556137

Fax

John.monro@plantandfood.co.nz

Contact person for public queries

Name

Suman Mishra

Address

The New Zealand Institute for Plant and Food Research,
Private Bag 11600
Palmerston North
New Zealand
4442

Country

New Zealand

Phone

+643556146

Fax

Suman.mishra@plantandfood.co.nz

Contact person for scientific queries

Name

John Monro

Address

The New Zealand Institute for Plant and Food Research,
Private Bag 11600
Palmerston North
New Zealand
4442

Country

New Zealand

Phone

+6463556137

Fax

John.monro@plantandfood.co.nz

No information has been provided regarding IPD availability

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.

Trial Review

Registering a new trial?

Documents added manually

Documents added automatically