None listed
Conditions
Brief summary
Mamaku (Cyathea medullaris) is a tree fern that grows widely in Aotearoa (New Zealand) and is regarded as a Taonga species. Mamaku contains a gum in its fronds and stem, located largely in the pith. This gum has a unique “shear-thickening” property which means that it, and the pith that contains it, can form highly cohesive dispersions in water-based media, such as the gut contents. The rheological properties of suspensions of mamaku pith lead to a suppression of physical processes such as mixing and diffusion, which are important in determining the rate of food digestion and absorption from the intestine. A reduced rate of absorption of glucose released during starch digestion has the important effect of lowering the blood glucose response to starchy foods. Hydrocolloids such as guar gum, psyllium husk, and many other gums that also increase the viscosity of gut contents have a well-established capacity to suppress the blood glucose (glycaemic) response to digestible carbohydrates. It is therefore highly probable, but not yet shown, that mamaku pith will be able to reduce the glycaemic response to carbohydrate foods consumed at the same time as the mamaku. An ability to reduce blood glucose concentrations is an extremely important property. High blood glucose is a defining feature of diabetes and metabolic syndrome, which are global epidemics. It is also responsible for many of the medical disorders associated with diabetes as blood glucose reacts chemically with molecules throughout the body. It also leads to a state of oxidative stress and associated suppression of immunity, so that many secondary disorders arise from chronic and chronically repeated bouts of high blood glucose, such as occur after carbohydrate meals. Foods and food ingredients that suppress postprandial (after-meal) glycaemic response may, therefore, find a ready market, especially in populations, such as in China, where it has been estimated that almost half the population is glucose intolerant. This is an opportunity for Maori business to use Mamaku, as a Taonga species, to found a business based on the anti-glycaemic properties of mamaku. But first it is necessary to establish that mamaku gum, in the form of mamaku pith, has the ability to suppress glycaemic response to carbohydrate food.
Interventions
This is a simple study with the primary aim of showing whether or not mamaku pith has the capacity to reduce post prandial glycaemic response to carbohydrate food consumed at the same time, as has been shown for food hydrocolloids with similar properties. Blood glucose response is the primary outcome, and associated insulin response and satiety are secondary outcomes.
This is a randomised single blinded placebo controlled crossover intervention study involving healthy young and middle-aged adult
This is a simple study with the primary aim of showing whether or not mamaku pith has the capacity to reduce post prandial glycaemic response to carbohydrate food consumed at the same time, as has been shown for food hydrocolloids with similar properties. Blood glucose response is the primary outcome, and associated insulin response and satiety are secondary outcomes. This is a randomised single blinded placebo controlled crossover intervention study involving healthy young and middle-aged adult volunteers within the age range 20-60 y. Before taking part in the study they will have read the participant information sheet, provided written consent, and been assessed against the inclusion and exclusion criteria for the study. We aim to recruit 20 volunteers from the general population in Palmerston North. Each participant will ingest each of five meal treatments, with the order of treatments randomised for each individual. Randomization of the treatment order will be carried out by a statistician at Plant & Food Research using random numbers generated in Microsoft excel. On trial days involving ingestion of test meals the participants will be asked to arrive at the clinic fasted, that is, not having eaten since 10 pm the previous evening, and having had a moderate evening meal before then. The participants will be asked to provide two baseline blood samples and rate their satiety on the visual analogue scale provided. They will then be asked to ingest their test meal within 10 minutes of the baseline blood sampling. Blood samples will be taken by finger prick at 15, 30, 45, 60, 90, 120 and 180 minute from baseline (T = 0). Ratings of appetite sensations over the same period will be made on a visual analogue scale. The meals (treatments) will be: 1. WeetBix (59.7 g) plus 250 ml water plus blackcurrant flavouring (100 mg blackcurrant flavour + 50 mg maltodextrin). 2. WeetBix (59.7 g) plus dried mamaku pith (5 g) dispersed in 250 ml water just before consuming plus blackcurrant flavouring. 3. WeetBix (59.7 g) plus dried mamaku pith (5 g) dispersed in 250 ml water an hour before consuming plus blackcurrant flavouring. 4. WeetBix (59.7 g) plus undried mamaku pith (10 g) blended with 240 ml water just before serving plus blackcurrant flavouring1. 5. WeetBix (59.7 g) plus guar gum (3 g) dispersed in 250 ml water just before serving plus blackcurrant flavouring. 1 A treatment with Mamaku at this concentration will be included at the request of the Maori research partner as they believe it to be effective, based on Maori experience. All meals deliver a dose of 40 g of WeetBix available carbohydrate of which about 96% is readily digested starch and 4% sugar. Participants will consume not more than two of the test meals per week with at least two days between each test meal. Therefore involvement in the trial will last for a minimum of three weeks. Adherence of the intervention will be by the researchers directly observing the participants during the 3 hours for each session. There will be a wash-out period of 48 hours between each treatment.
Sponsors
National Science Challenge - High Value Nutrition
Study design
Allocation
Randomised controlled trial
Intervention model
Crossover
Primary purpose
Prevention
Masking
Blinded (masking used) (Subject)
Eligibility
Sex/Gender
All
Age
18 Years to 65 Years
Healthy volunteers
Yes
Inclusion criteria
• Age: 18-65 years. • Sex: Any gender. • BMI between 18 and 35. • Health: Healthy as gauged by self-assessment and result on the General Health Questionnaire. • No indication of impaired glucose metabolism as indicated by fasting blood glucose and HbA1c determined on finger-prick samples. • Agreement: Participant having given written informed consent to comply with the conditions of the trial. • No allergic reaction to wheat products.
Exclusion criteria
• Fasting blood glucose > 5.6 mmol/L and HbA1c > 40 mmol/mol • Allergic to or intolerant of wheat products. • Any gastrointestinal disorder. • Unwilling or unable to provide informed consent or comply with the study procedures. • Having Type I or II diabetes.
Outcome results
None listed