KINGS Gastric Study

As of November 2023, recruitment of participants for the KINGS Gastric Study has closed. The research team would like to thank everyone who expressed an interest in taking part, and especially those participants that completed all study visits.

KINGS stands for Kiwifruit Ingestion to Normalise Gastrointestinal Symptoms.

We want to find out if habitual consumption of green kiwifruit will improve abdominal pain and other gastrointestinal symptoms, lead to changes of the gut microbiome, and improve gastric motility in individuals with functional constipation (FC) and constipation-predominant irritable bowel syndrome (IBS-C).

Functional gastrointestinal disorders (FGIDs) are common in the general population, and can have a negative impact on quality of life, work productivity and cost of the healthcare system. The most common FGIDs are functional constipation and irritable bowel syndrome. Studies have shown that many of the affected individuals do not consult a GP and might be silently managing their FGID symptoms.

Green kiwifruit consumption has been shown to provide digestive benefits and relief from constipation. However, the mechanisms of action are not well understood.

The study aims to investigate the effect of daily consumption of two green kiwifruit over 28 days on abdominal discomfort and pain, gut microbiome, and gastric motility in individuals with constipation.

We hypothesise that the habitual consumption of two green kiwifruit per day for 28 days will improve abdominal discomfort and pain; improve bowel habits; result in changes in gut microbiota and physiology profiles towards normalisation; and improve gastric motility and emptying in individuals with FC and IBS-C.

Through this study, we hope to understand how green kiwifruit affects bowel function and how it might be effective in treating constipation.

You can take part if you:

• are 18-65 years old
• have a BMI between 18 – 35kg/m2
• either have functional constipation or constipation-predominant irritable bowel syndrome, or a healthy gut.

The study will be conducted at the Liggins Institute in Auckland and your mahi / help will be rewarded with petrol/shopping vouchers to the value of $220 for completing all 5 study visits.

Yes, the KINGS study was running in Christchurch, at the University of Otago in 2022. The Christchurch site has closed recruitment.

The study duration will be eight weeks: 2 weeks lead-in phase, 4 weeks intervention phase, and 2 weeks follow-up phase.

You will be asked to consume 2 green kiwifruit per day during the 4-week intervention phase. All green kiwifruit will be provided.

The following procedures will be required to complete the study:

• Attending 5 visits: screening visit (1 hour) to determine eligibility; enrolment visit (1 hour), two assessment visits (4 hours each), and follow-up visit (1 hour) over the course of 2 months.
• We will collect your blood and faecal samples.
• You will need to complete health-related questionnaires and keep food and symptoms diaries.
• You will maintain your current lifestyle and dietary habits, i.e., we do NOT give advice and treatment.

You may or may not benefit from taking part in this study. There is no guarantee that you will experience any changes in stool frequency or satisfaction from taking any of the study products. You will, however, gain knowledge regarding bowel health and be given green kiwifruit for yourself and your immediate family/whanau/fellow living companions following the completion of the study.

Additionally, if we are successful in understanding constipation and its treatment with food, we may be able to develop improved ways of diagnosing and treating FC and IBS-C in the future.

There are no substantial risks involved with this study. 

If you are interested in learning more about this study, please contact nutrition.liggins@auckland.ac.nz.

This project has been reviewed and approved by the New Zealand Health & Disability Ethics Committees (HDEC). Reference: NZ/21/NTB/96.