Public Summary

Principal investigators: Alex Kanon, under the supervision of Dr Sharon Henare, Ngāti Whātua, Ngā Puhi, Senior Lecturer in the College of Health at Massey University
Industry partners: Zespri International Limited
High-Value Nutrition funding: $31,800

Kiwifruit for sleep

This study examines the effects of green kiwifruit on sleep quality and the sleep-wake cycle in healthy males. Kiwifruit has been shown to improve digestive health and, more recently, psychological well-being.

This study builds on previous research, which showed that sleep quality is improved with the daily consumption of two Aotearoa New Zealand green kiwifruit for four weeks.

Riddet Institute-funded PhD candidate Alex Kanon, under the supervision of Dr Sharon Henare, Ngāti Whātua, Ngā Puhi, Senior Lecturer in the College of Health at Massey University are working with Zespri International Limited to investigate the benefits of eating fresh green kiwifruit (without skin). They will determine if the consumption of this fruit improves sleep quality and increases the urinary concentration of metabolites central in the regulation of sleep-wake cycles. They will also research freeze-dried kiwifruit to find out if this are added benefits to consuming the fruit in this form.

“There is some evidence from scientific studies that kiwifruit promotes sleep but how it does that we don’t really know.

“We’re interested in identifying the mechanism by which kiwifruit may be acting to improve sleep and whether this involves an increase in the neurochemicals responsible for the regulation of sleep-wake cycles. The potential to use a natural product such as having kiwifruit after dinner appeals as a simple solution to improve sleep.” Says Dr Sharon Henare, Senior Lecturer, Massey University.

Sleep is essential for the cellular repair of the body. One night of sleep disturbance can affect a person’s ability to concentrate which may increase technical errors and decrease overall mood the following day. In addition, sleep, or the lack of it, is increasingly recognised as a risk factor for obesity, type 2 diabetes and cardiovascular disease.

Sleep promoting foods have been shown to increase the levels of the neurohormone melatonin and its precursor serotonin. Both hormones play central roles in the regulation of sleep-wake cycles.

New Zealand grows top quality kiwifruit that has a nutrient-dense flesh and skin that is high in vitamin C, folate and fibre. Kiwifruit also contains 6ug/g of serotonin, which is considered high[vi].

The project is a multi-arm, randomised, controlled, trial that includes 24 men – 12 with poor sleep quality, and 12 with good sleep quality and will assess sleep quality in response to their evening meal supplemented with either fresh green kiwifruit (without the skins), whole freeze-dried green kiwifruit powder (including the skin), or water.

The project aims to determine the effect of green kiwifruit on objective and self-reported sleep quality and also the effects of green kiwifruit on self-reported psychological well-being.

“This study strongly aligns with HVN’s mission and strategy to develop high-value foods with validated health benefits to drive economic growth through research excellence.

“The anticipated outcomes may reveal the potential for the formulation of unique Aotearoa New Zealand kiwifruit-based products with health messaging related to sleep quality and mood, while also potentially bringing increased economic benefits for kiwifruit growers.”
Says Joanne Todd, High-Value Nutrition Challenge Director.

Research team