AbstractsMedical & Health Science

The function of dietary phenolic acids in cardiovascular health

by Aidilla Mubarak

Institution: University of Western Australia
Degree: PhD
Year: 2013
Keywords: Phenolic acids; Cardiovascular; Fruit; Chlorogenic acid
Record ID: 1031869
Full text PDF: http://repository.uwa.edu.au:80/R/?func=dbin-jump-full&object_id=34692&local_base=GEN01-INS01


[Truncated abstract] Dietary phenolics have been associated with protection against the various forms of cardiovascular disease (CVD). This thesis outlines three independent studies, from analytical to intervention, which increase our knowledge on the role of phenolic compounds in preventative health. Particular attention was paid to phenolics found in fruit, as they are a rich source and widely available and consumed, and hence make a large contribution to dietary phenolics intake. While many fruits are rich in phenolic compounds, it is known that specific cultivars vary greatly in phenolic composition. In this thesis, the composition of major phenolics in 29 pre-varietal selections of Western Australian plums was investigated. This knowledge was essential as the first step in a pathway to develop breeding tools to aid identification of fruit that may have enhanced health-promoting capacities. Total phenolics, selected individual phenolic compounds and total antioxidant capacity (TAC) were quantified. Total phenolic concentration was significantly correlated with TAC. Neo-chlorogenic acid and quercetin glycosides were found to be the predominant phenolics. Composition of these predominant phenolic compounds in plums was not significantly correlated with the TAC. In this study, it is argued that the value of in vitro TAC assays to breeding programs may be limited. Further, increasing the focus on individual bioactive phenolic compound was also argued to be more productive to breeding than TAC assays, as patterns of inheritance of TAC are likely to be very complex. Further understanding on the mechanisms of phenolics in preventative health was sought. There is increasing evidence that specific dietary phenolics can enhance production of nitric oxide (NO) a mediator in vascular health. A randomized, double-blind, placebo-controlled, cross-over trial in healthy men and women (n = 23) was conducted to investigate the acute effects of chlorogenic acid on blood pressure, NO status and endothelial function. A dose of 400 mg chlorogenic acid (equivalent to 2 cups of coffee) was chosen as an amount achievable in a usual diet. Relative to control, systolic blood pressure and diastolic blood pressure were significantly lower after 400 mg chlorogenic acid treatment. This result was observed without concomitant enhancement in biomarkers of NO status and endothelial function assessed by flow mediated dilatation. In this study, it was concluded that chlorogenic acid can lower blood pressure acutely; an effect which if sustained would benefit cardiovascular health. To further understand the potential benefits of chlorogenic acid on CVD, it is also important to recognize its effect on metabolic abnormalities which are known to be a significant risk factor of developing CVD. Benefits of chlorogenic acid on several features of the metabolic syndrome through coffee consumption were proposed. In this thesis, an 11-week dietary intervention study was performed to assess whether chlorogenic acid (1 g.kg-1 diet) had a protective effect…