Abstract/Summary

The gut-brain axis (GBA) is emerging as a complex communication that can impact on emotional and cognitive centres of the brain. The aim of this work was to investigate the effect of prebiotics such as inulin and blueberry flavonoids on the gut microbiota composition and associated neuroactive metabolite production. In order to assess the mechanism of how gut microbiota might impact on cognitive functions, a series of in-vitro studies and one human trial was performed. A combination of in vitro models was initially used to access if the microbiota could produce molecules related to neurological pathways in the absence of human cells and then to determine if supplementation with blueberries or prebiotics could result in enhanced levels of neuroactive metabolites along with growth of beneficial gut bacteria. Data supported the positive shift of gut bacteria and the production of metabolites, therefore a more complex gut model system was used and indicated increased potential for these interventions to support the gut brain axis. Finally, a pilot intervention study was carried out to explore links of the in vitro findings with the in vivo situation with children aged 7-10 years old, who would be undergoing rapid cognitive changes. Following intervention a significant increase in the % abundance of Faecalibacterium prausnitzii for the inulin group was observed. Moreover, both inulin and berry groups experienced significantly higher accuracy in an attention network task and significant increases the memory tasks. These results are promising as to show a potential for inulin to have direct effects on GBA through microbiota, whilst the cognitive changes observed of berries might be by a different pathway. Although larger trials are necessary this thesis indicates that the GBA can be altered through diet and both prebiotics and berries may be relevant foods to support these changes.