The University of Auckland
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HVN1906 Metadata Record - Mamaku effects on blood glucose response

posted on 2024-04-10, 04:44 authored by John Monro, Garry Watson

This metadata record and it's attached files make statements about the kinds of data collected as part of this research, and set out policies for governance of that data, now and in the future.

Description: 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 Māori 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.



University of Auckland

Temporal coverage: start


HVN Project / Programme Name


Data access requirements

No individual data will be shared.

Principal investigator organisation

Plant and Food Research

Collaborating researchers and affiliations

Principal investigators: Dr John Monro, Plant and Food Research, Palmerston North Garry Watson, Nga Uri o te Ngahere Trust Associate investigators: Josh Watson (Te Rangitahi o te Whenua Trust) Dr Lara Matia-Merino (Massey University) Associate Professor Kelvin Goh (Massey University) Dr Suman Mishra (Plant and Food Research)

Data description

Outcomes of the Study and associated data Primary Outcome: - Blood glucose response pre and post meal treatment Associated data: Blood glucose level, blood insulin level Secondary Outcomes: - Changes in insulin pre and post meal treatment - Changes in satiety pre and post meal treatment - Changes in feeling of gut comfort pre and post meal treatment Associated data: Blood insulin level, Visual Analogue Scale (VAS) questionnaire, Gastrointestinal Symtom Rating Scale (GSRS) questionnaire

Principal investigator contact email