Exploring kiwifruit’s potential as a natural sleep and mood booster

Born and raised in Auckland, Dr Kanon left for Australia to complete his undergraduate studies before joining the Commonwealth Scientific Industrial Research Organisation (CSIRO). The organisation’s strong partnership with the Riddet Institute and AgResearch inspired him to move to Palmerston North to undertake his Doctor of Philosophy (PhD) at Massey University.

With a background in food science, nutrition and physiology, Dr Kanon had previously researched the nutritional determinants of brain health in preterm infants. For his doctoral work, he turned his attention to kiwifruit after early studies in both pigs and humans showed promising effects on digestion, metabolism and immunity, along with improved blood-glucose control, better nutritional status and enhanced digestive comfort. The first stage of his PhD aimed to determine whether green or gold kiwifruit delivered the most meaningful changes to brain function.

His animal study revealed clear differences between the two kiwifruit varieties. Both green and gold kiwifruit shifted the gut microbiome toward more beneficial bacterial species and away from potentially harmful ones, but each showed distinct strengths. Green kiwifruit had a more pronounced impact on brain neurotransmitters and antioxidant protection, while gold kiwifruit also influenced neurotransmitter levels but did not show antioxidant effects, despite its higher vitamin C content.

“In our study, the key difference between green and gold kiwifruits came down to enzyme actinidin,” Dr Kanon explains.

“Green kiwifruit naturally contains this enzyme, while the gold variety we used did not. That gold cultivar is no longer sold in New Zealand due to past disease issues, but having access to it gave us a unique control. When we looked at brain chemistry, we found clear differences between the two fruits, and green kiwifruit consistently showed higher levels of several neurotransmitters across different brain regions.”

The second stage of his PhD focused on a human trial comparing two forms of green kiwifruit: fresh fruit without the skin, and freeze-fried whole kiwifruit that retained the nutrient-rich skin. Participants were divided into two groups – those with good sleep health and those who reported poor sleep.

“In both groups, we saw changes in serotonin-related metabolites after eating both forms of green kiwifruit, along with improvements in both sleep and mood,” Dr Kanon says.

The trial revealed that the form of kiwifruit that worked best differed depending on sleep quality. The freeze-dried kiwifruit appeared particularly helpful for people with poor sleep, while those who already slept well responded more strongly to fresh fruit. Overall, retaining the skin delivered greater improvements in several sleep and mood outcomes.

Dr Kanon hopes his findings will support everyday people to improve their sleep, mood and general brain health, while also offering economic benefits for Aotearoa by highlighting the value of kiwifruit and other functional foods in global markets.

His PhD journey took place largely during the COVID-19 pandemic, demanding flexibility and creative problem-solving.

“There were several changes along the way, including how experiments were conducted due to lockdowns and restrictions. Designing the research this way allowed us to continue generating meaningful data while navigating these challenges.”

Looking back, Dr Kanon says the most rewarding part of his PhD was the people and connections built along the way.

“I was surrounded by amazing students, colleagues and a supportive research environment. I loved travelling to conferences, meeting new collaborators and learning new techniques. Those experiences really shaped my work.”

Having recently completed postdoctoral studies at APC Microbiome Ireland, he is now based in Brisbane and seeking a new role focused on sleep, mental wellbeing and nutrition.

“I’m particularly interested in applying my experience in brain health and functional foods to research or projects that can have a real impact on people’s everyday health.”

Dr Kanon’s PhD was sponsored by the Riddet Institute, supported by Zespri and Alpha Group Holdings, and received contestable funding from High-Value Nutrition. He says these partnerships were invaluable in enabling the research and provided strong industry and academic guidance.

For current and future PhD students, he offers simple, hard-earned advice: stay flexible, stay organised and lean on your support network.

“Studies involving both lab work and human participants rarely go exactly as planned, so being able to adapt, and keeping good records, is essential. And remember to celebrate the small wins. They really do keep you going.”