Metabolic effects of consuming carbonated water or kiwifruit on a daily basis over seven-weeks

INTERVENTION: This will be a parallel randomized trial of two groups over seven‐weeks. One group will consume two gold kiwifruit and 500mL carbonated water as a preload to breakfast each day (consumed within the 30 minutes leading up to breakfast). Prior to the intervention, participants’ normal breakfasts will be characterized by asking them to fill in weighed breakfast records for 7 days. The intervention will involve reducing breakfast by an amount equivalent to the carbohydrate contained in the gold kiwifruit preload. For example, if a person ate two slices of jam on toast for breakfast, one of those slices would be replaced by gold kiwifruit. This strategy may produce measurable benefit to metabolic markers over seven weeks; sufficient time for changes in lipids and glycaemic markers to occur. We will obtain breakfast records and train people how to substitute part of their breakfast with the gold kiwifruit. If the habitual breakfast contains fat, this will be removed propotionately with amount of CHO that is substituted with gold kiwifruit, providing a mechanism by which blood lipids would be affected. To monitor adherence we will record kiwifruit/carbonated water collection visits and obtain diet records during the intervention period. This intervention will be conducted by a postgraduate student with a Master of Science in Human Nutrition as part of her PhD with supervision by senior university and Crown Research Institute staff. CONDITION: Blood lipids Hyperglycaemia Hyperinsulinaemia PRIMARY OUTCOME: Between group difference in fasting blood glucose concentration, adjusted for baseline, using blood obtained via capillary at visits 1, 2, 5, and 6. Blood glucose will be measured using a Hemocue instrument. Between group difference in fasting plasma insulin concentration, adjusted for baseline, using blood obtained via venipuncture at visits 1, 2, 5, and 6. Plasma insulin will be analysed using a Roche Elecsys electrochemiluminescence immunoanalyser SECONDARY OUTCOME: Change in plasma metabolomics Change in plasma total cholesterol Change in plasma triglycerides Change in plasma uric acid INCLUSION CRITERIA: Healthy adults