Kiwi, Fruity and Friendly

Research Team

Dr John Monro

Dr John Monro is a Principal Scientist at Plant and Food Research. John has studied dietary fibre in the fore and hind gut, physiologically valid determination of its functional properties, and how to communicate its effects to accurately guide food choices for health. More recently his research has focused on digestible carbohydrates in foods, on valid determination of carbohydrate availability by in vitro digestive analysis, and on food structural factors that modulate the glycaemic response. John is a lead researcher on the postprandial and long term clinical trials for the Kiwi, Fruity and Friendly research project funded by High-Value Nutrition and Zespri Ltd. 

ORCID ID: https://orcid.org/0000-0001-6111-5571

Public Summary

Principal Investigator: Dr John Monro, Plant & Food Research

Collaborating Organisations: University of Otago, AgResearch

The programme “Kiwi, fruity and friendly” was strongly focused on two key issues facing those marketing kiwifruit in Asia. They are:

  1. Maintaining sales of a sugar-rich fruit in a market where there is a high and increasing incidence of diabetes, and a growing fear of the effects of high-sugar foods, such as fruit, on blood glucose.
  2. Assuring Asian consumers that an increased intake of fruit sugar (fructose) resulting from regular consumption of kiwifruit will not lead to adverse metabolic effects, such as high blood pressure, increased blood lipids (cholesterol, triglycerides) and obesity, which effects have been attributed in part to fructose in the diet.

Zespri acknowledged these issues as important to their business, and generously co-funded the research.

Both of the above issues were successfully addressed in the research, and Zespri immediately made use of the results in marketing kiwifruit to Asian consumers.

In the first of three clinical trials, healthy New Zealand Chinese participants consumed kiwifruit as part of a carbohydrate meal, in which the kiwifruit carbohydrate partially substituted the primary meal carbohydrate. Total carbohydrate in the meal was held constant yet the kiwifruit was able to significantly reduce the blood glucose response. And if the kiwifruit was consumed about 30 min before the main carbohydrate intake, there was a dramatic reduction in the post-meal blood glucose spike.

In a second trial, also with healthy Chinese participants, we measured the effect of consuming two kiwifruit per day for seven weeks on clinical risk factors for disease that could result from adverse metabolic reactions to fructose. The measurements included a number of risk factors for diabetes and cardiovascular disease, including weight gain, blood lipids and other biomarkers. No adverse metabolic reactions were observed, suggesting that daily consumption of two kiwifruit over a moderately extended period is metabolically safe.

A third trial focused on participants who were of mixed race but who were all pre-diabetic and therefore had a high risk of developing diabetes. As before, the aim was to determine whether or not increased intakes of fructose due to consumption of two kiwifruit per day over a long period could cause harmful metabolic changes in individuals judged by medical criteria as being at high risk of “metabolic syndrome”. The third trial ran for three months – enough time for glycosylated haemoglobin (HbA1c) concentrations in the blood to register increased exposure to glycaemia during the trial period. Several clinical biomarkers were measured, as well as plasma Vitamin C. There were no differences between the kiwifruit and control (water) groups in weight gain, blood lipids, HbA1c and other clinical measures, while plasma Vitamin C increased in the kiwifruit group. The results showed that kiwifruit, although containing fruit sugars, may be consumed as an excellent source of Vitamin C, by people at risk of diabetes, without unwanted metabolic side effects.

The research team demonstrated an effective combination of the skills required to plan the research, achieve the research goals and deliver outputs on time. To complete and write up three clinical trials in three years showed a high level of team collaboration and science excellence. The programme was also used as an opportunity to provide post-graduate training to three students pursuing higher degrees (PhD and Masters).

The research has provided valuable information in support of a major New Zealand industry. It addressed multiple HVN research themes in that it demonstrated a wellbeing benefit of a food strongly associated with New Zealand, it used biomarkers to define a food-health relationship, and it produced evidence that kiwifruit marketers can use to increase Chinese consumers’ motivation to purchase kiwifruit.

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