None listed
Conditions
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.
Interventions
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.
Foods:
The test foods will be as follows:
1. Glucose 50 g (reference) di
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. Foods: 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.
Sponsors
New Zealand Institute for Plant & Food Research
Study design
Allocation
Randomised controlled trial
Intervention model
Crossover
Primary purpose
Prevention
Masking
Open (masking not used)
Eligibility
Sex/Gender
All
Age
21 Years to 40 Years
Healthy volunteers
Yes
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.
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
Outcome results
None listed