None listed
Conditions
Brief summary
Potatoes are one of the most popular vegetables in the western diet. However, potatoes have a bad reputation as they generally induce a high blood glucose response after consumption. Our previous research measuring the glycaemic index (GI) of NZ potatoes gave an average GI of 86 (unpublished). However, in another trial, we found that potatoes were most satiating compared to pasta and rice when consumed on equal carbohydrate basis (Zhang et al. 2018). Yet another of our research projects has shown that blood glucose response to potatoes when co-consumed with salmon was significantly reduced (Ballance et al. 2018) compared with when the potato was consumed without salmon. Therefore, the aim of this trial to study the effect of lamb or plant protein (soy) on blood glucose and insulin responses to potatoes, rice and pasta to determine: 1. The relative glycaemic impact of potato when co-consumed with meat (protein) or plant protein (soy). 2. The glycaemic benefit of co-consuming protein with carbohydrate food. 3. The relative ability of meat and plant protein to reduce glycaemic response. References: Ballance S, Knutsen SH, Fosvold OW, Fernandez AS, Monro J 2018. Predicting mixed-meal measured glycaemic index in healthy subjects. European Journal of Nutrition. Zhang Z, Venn BJ, Monro J, Mishra S 2018. Subjective Satiety Following Meals Incorporating Rice, Pasta and Potato. Nutrients 10(11).
Interventions
The study is a randomized repeated measures design which means you will be asked to consume nine test foods, in random order, one per testing session as a single meal. Therefore you will need to be available for nine testing sessions.
The test meals will be as follows:
1. Boiled potato only (40g available carbohydrate)
2. Cooked pasta only (40 g available carbohydrate)
3. Cooked rice only (40 g available carbohydrate)
4. Boiled potato (40g available carbohydrate) + cooked mince lamb (84g – 1 se
The study is a randomized repeated measures design which means you will be asked to consume nine test foods, in random order, one per testing session as a single meal. Therefore you will need to be available for nine testing sessions. The test meals will be as follows: 1. Boiled potato only (40g available carbohydrate) 2. Cooked pasta only (40 g available carbohydrate) 3. Cooked rice only (40 g available carbohydrate) 4. Boiled potato (40g available carbohydrate) + cooked mince lamb (84g – 1 serve) 5. Cooked pasta (40 g available carbohydrate) + cooked mince lamb (84g – 1 serve) 6. Cooked rice (40 g available carbohydrate) + cooked mince lamb (84g – 1 serve) 7. Boiled potato (40g available carbohydrate) + soy meat (cooked textured vegetable) protein (150g – 1 serve) (commercially sourced) 8. Cooked pasta only (40 g available carbohydrate) + soy meat (cooked textured vegetable protein) (150g – 1 serve) (commercially sourced) 9. Cooked rice only (40 g available carbohydrate) + soy meat (cooked textured vegetable protein) (150g – 1 serve) (commercially sourced) An additional 200 ml of water will be consumed with all diets. Individuals will be chosen to participate in the study if they are within the age bracket (18-65) and considered to be generally healthy. Health status will be determined initially by the use of a health questionnaire, which asks about your current and past health issues. During the study, you will be required to refrain from eating after 9 pm and avoid any strenuous physical activity on the night preceding testing. We ask that you consume a similar evening meal before each of the 9 test days. In the morning you will be asked to rest for 15 mins before 2 baseline blood samples (by finger prick) are taken. You will then be given one of the nine test meals to consume within 10 mins and small blood samples will be taken at 0 (2 x, baseline), 15, 30, 45, 60, 90, 120 and 150 min after consuming the food. Blood sampling involves the use of a finger prick device which allows a small amount of blood to be massaged from the finger at each sampling time and used to monitor your blood glucose and insulin levels over the two and a half hours after consuming the food. During the 2.5 hours you will be able to continue with your normal work if it is not strenuous (e.g., office work), and drink a set amount of water if thirsty but consume no food until after the final blood test. Otherwise, you will be asked to rest and do some non-strenuous activity such as reading. You will be asked to fill out a visual analogue scale to assess your hunger at 0, 30, 60, 90, 120 and 150 mins. Lunch of your choice from the cafeteria options will be available free after the testing has been completed. If you agree to take part in the study, we would like you to be available in the morning. Each visit will last a maximum of three hours. 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
18 Years to 65 Years
Healthy volunteers
Yes
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. • Tolerant to potato, pasta, rice, meat and plant protein. • 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 less 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. • Vegetarian or vegan • Allergic or intolerant to potatoes, pasta, rice, plant protein and meat • Pregnant or breastfeeding. • Long term chronic illnesses requiring treatment, such as cancer and cardiovascular disease. • Gut conditions or drugs effecting gut transit time, such as irritable bowel syndrome, peptic ulcers and laxatives.
Outcome results
None listed