Consumption of fresh or dried kiwifruit in the evening improves aspects of sleep quality and mood, potentially mediated through changes in serotonin metabolism.
Randomised Controlled Trial Kiwifruit Serotonin Sleep
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.
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