Abstract/Summary

Following recent interest in the maintenance of health and wellbeing through dietary intervention, the acute cognitive benefits of wild blueberries were investigated in healthy young adults. Blueberries have shown promise in their ability to mediate postprandial cognition and mood; however the effects of dose, and potential mechanisms of action, are yet to be fully elucidated. My thesis, therefore, aimed to determine whether cognition and mood effects following wild blueberry supplementation were dose dependent, and whether modulation of postprandial glucose response was a likely mechanism of action, through increased availability of glucose to the brain. The cognitive and physiological effects of wild blueberry doses, containing 129mg-724mg anthocyanins, were investigated across three placebo controlled, crossover experiments. Data were analysed using linear mixed-effects modeling, and key findings were identified through pairwise comparisons. Observed dose-dependent cognitive benefits included the maintenance of immediate recall on a single-trial word list learning task, the improvement of working memory on a serial subtraction task, and the attenuation of negative affect using a self-report questionnaire. In addition, dose-dependent attenuation of postprandial heart rate decline was suggestive of increased glucose availability. Further investigation revealed dose-dependent effects on postprandial blood glucose regulation, including attenuation of postprandial glucose peak, and extended availability of blood glucose. In all cases, the strongest effects were observed following blueberry doses containing 517mg anthocyanins or higher. Few significant effects were observed following lower doses. With some statistical caveats, this programme of research is the first to demonstrate a dosedependent effect of anthocyanin-rich wild blueberries on episodic memory, working memory and mood. The research also indicates a dose-dependent glucoregulatory effect that may provide a plausible mechanism of action for observed cognitive benefits. Future research should consider the potential application of wild blueberries as a treatment or preventative intervention for metabolic disorders such as type 2 diabetes, where both cognition and glucoregulation are typically impaired.