Insights & Discussion
Consumption of fresh or dried kiwifruit in the evening improves aspects of sleep quality and mood, potentially mediated through changes in serotonin metabolism.
A randomized, single-blind crossover study involving 24 men with varying sleep quality levels was conducted. Participants were provided with one of three treatments during their standard evening meal at home: the flesh of two fresh green kiwifruits, dried green kiwifruit powder (with skin and equivalent to the dry matter of two fresh kiwifruits) mixed with water, or a water control. Various factors were evaluated including subjective and objective sleep quality, mood, and urine concentration of several compounds including the serotonin metabolite 5-HIAA, vitamin C, and B-vitamins.
Findings indicated that regardless of sleep quality group, dried kiwifruit consumption was associated with an improvement in morning sleepiness, alertness upon waking, and vigor as compared to the control. Both fresh and dried kiwifruit treatments suggested an improvement in self-esteem and overall mood disturbance. Increase in the urinary concentration of serotonin metabolite was observed with both kiwifruit treatments. Amongst poor sleepers, ease of awakening was notably improved after the intake of dried kiwifruit and showed signs of improvement with fresh kiwifruit. For good sleepers, there seemed to be an improvement in getting to sleep with fresh kiwifruit. Poor sleepers were found to have lower quantities of certain B-vitamins compared to good sleepers. Thus, both dried and fresh kiwifruit consumption with a standard evening meal showed a positive impact on sleep quality and mood.
Discover Related Insights
Consuming New Zealand green kiwifruit improves sleep quality, mood, and increases the concentration of serotonin metabolites.
2022 NSNZ 2021 Acute Evening Consumption of Green Kiwifruit in Young Men Enhances Waking Alertness, Mood and Increases 5-Hydroxyindoleacetic Acid in Urine Kanon AP, Giezenaar C, Roy NC, McNabb WC, Henare SJ
Randomised Controlled Trial Kiwifruit Mood Serotonin
A total of 24 men, ranging in age and with varying sleep quality were selected for the study, in a single-blind crossover design, which was randomized. Participants were provided three treatments on separate occasions, each differing by 6-8 days: consumption of two fresh kiwifruits, ingesting green kiwifruit powder mixed with water equivalent to two fresh kiwifruits, or a simple water control.
Poor sleepers noted that they woke up more easily after consuming dried kiwifruit, with a similar but less pronounced trend observed when they consumed fresh kiwifruit. Conversely, good sleepers showed a trend towards better sleep initiation with fresh kiwifruit, but not with the dried kiwifruit. Independent of the participants' sleep quality, both fresh and dried kiwifruit largely improved mood and self-esteem. Consumption of dried kiwifruit significantly elevated morning alertness, post-wakening behaviour, and vigour. Both forms of kiwifruit ingestion led to higher urinary concentrations of the serotonin metabolite known as 5-HIAA.