Zajac, Ian TKakoschke, NaomiBlatchford, Paul (Zespri International Ltd)Billows, Michael2024-07-112024-07-112024https://hdl.handle.net/2440/141582Mental health disorders, including depression, contribute significantly to the individual, societal and global burden of disease. Increasingly, diet quality is seen as a modifiable risk factor for mental health. There is preliminary support for healthy dietary intake to confer benefits to mental health in clinical populations through the delivery of vitamins and nutrients associated with mood. This thesis presents the results of a rapid review of the literature and two intervention trials that examined the potential for gold kiwifruit, a nutrient-dense fruit rich in vitamin C, to support psychological health and wellbeing in adults with mild to moderate mood disturbance through increased vitamin C intake. In Study 1, a rapid review of the literature was undertaken to identify intervention trials that used a green or gold kiwifruit intervention and assessed mood outcomes. The rapid review sought to identify any supporting evidence within sub-clinical mental health populations, and to explore the potential clinical implications of kiwifruit as a dietary intervention in mood-disturbed populations. The review identified nascent research that reported gold kiwifruit was associated with improved mood and wellbeing in otherwise healthy adults with sub-optimal vitamin C status. Study 2 was a multiple N-of-1 feasibility trial that assessed the practicality of recruiting adults aged 18 to 60 years with mild to moderate mood disturbance and sub-optimal vitamin C status. The feasibility trial demonstrated difficulties with participant recruitment, which likely reflected the strict exclusion criteria. Results suggested that a larger trial was feasible but required careful consideration of criteria due to the impact on recruitment and compliance with data collection. Study 3 was a two-period, non-blinded crossover trial in which participants (n = 26) with mild to moderate mood disturbance were randomised to a counter-balanced sequence. During each 4-week period, participants consumed either two SunGold kiwifruit daily or their usual diet, with the periods separated by a two-week washout. Mean change in total mood disturbance (p < 0.001) and wellbeing (p < 0.01) were greater in the kiwifruit condition relative to diet as usual. Vitamin C (p = 0.002) and vitality (p = 0.001) also improved in the kiwifruit condition. These results highlight the potential for gold kiwifruit to improve mood in adults with mild to moderate mood disturbance. This dissertation presents three studies that contribute to the emerging work focussed on diet and nutrient intake as adjuvant treatments for mental health. The studies demonstrate that gold kiwifruit is well-positioned to serve as a nutritious whole food that confers positive benefits to psychological health. Further research to identify the mechanisms of action of the panoply of nutrients in gold kiwifruit across diverse populations is required.enKiwifruitpsychological wellbeingvitamin CmoodThesis