Dietary bioactives and cardiovascular health

Abstract

The primary objective of this thesis was to investigate the efficacy of dietary bioactive compounds on cardiovascular disease (CVD) risk markers in adults with mildly elevated blood pressure (BP) through the implementation of two human dietary intervention studies: the Cardio-Rubus (blackberry-polyphenols) and Cardio-Protein (ovalbumin-derived peptides) randomised controlled trials (RCTs). Our findings indicate that the consumption of ovalbumin-derived peptides for 6-weeks does not have an effect on BP, blood lipids or glycaemic profile in adults [Cardio-Protein RCT]; similarly, supplementation with a polyphenol-rich blackberry beverage for 6 weeks does not appear to lower BP or improve blood lipids or glucose homeostasis in adults [Cardio-Rubus RCT]. In this RCT, considerable heterogeneity in participant responses to the polyphenol-rich beverage were observed. Inter-individual variation in participant response to polyphenol-based interventions has become a major challenge for the establishment of causal relationships between polyphenols and health outcomes. This was further reinforced in the findings of a systematic review evaluating evidence from berry-based RCTs on markers of cardio-metabolic health, which was conducted as part of this thesis. Of a total of 23 RCTs; 17 were ranked to be of high quality, of these 12 RCTs reported a beneficial effect on CVD risk, supporting consumption of berries as part of a cardio-protective diet. This thesis includes the first study to estimate dietary intakes of polyphenols in Irish adults, teens and children using nationally representative data. Beverages were the predominant contributor; providing a feasible method by which to increase polyphenol intakes. A modelling assessment demonstrated that hypothetically a polyphenol-rich beverage could meaningfully increase polyphenol intakes in the Irish population. Findings from this thesis inform and aim to address current challenges which face dietary interventions with bioactive compounds for the advancement of polyphenol research and the establishment of a causal link between polyphenols or peptides and cardio-metabolic health outcomes.