Effect of Fruit Anthocyanin Consumption on Cognition, Blood Pressure and Other Health Parameters in Older Adults

Epidemiological evidence has shown that dietary factors, as part of lifestyle behaviours, have significant positive effects on the onset and progression of neurodegenerative disorders including dementia and other chronic diseases. Plant-rich diets especially, have been shown to have significant protective effects on overall health. This is due to the presence of phytochemicals, minerals, vitamins and dietary fibre in these foods. Phytochemicals are classified under carotenoids and polyphenols; which include flavonoids, phenolic acids, and stilbenes/lignans. Anthocyanins are a subclass of flavonoids responsible for the dark red-purple colours in fruits and vegetables. In the last decades, there has been an increased research interest in anthocyanins which is attributed to their antioxidant characteristics - the ability to reduce oxidative stress in living cells. The association between anthocyanin from dietary sources and cognitive function is yet to be fully established. Available evidence suggests that anthocyanins may exert protective effects on cognition, including memory and executive processing, either through a direct effect on brain function or indirectly by reducing blood pressure. In order to determine the clinical effects of anthocyanins, a better understanding is required of the uptake and metabolism of these bioactive compounds found in fruits and vegetables. Intact anthocyanins are believed to reach the large intestine and colon where they undergo intensive metabolism and transformation with observed modulatory effects on gut microbiome. Following further degradation, they are absorbed into the bloodstream, with some of the subsequent metabolites showing potential to be more biologically active than the intact anthocyanins. The primary aim of this doctoral thesis was to determine the health benefits associated with both acute and longer-term effects of consumption of dietary anthocyanins, delivered in a fruit variant, Queen Garnet plum (QGP), on cognition, blood pressure and other health parameters in younger (acute) and older adults (acute and longer-term). In order to contextualise the findings for dietary guidance to the target population, the anthocyanin intake of the Australian population was assessed using a novel anthocyanin food composition database developed during the course of this research.