The Vascular Response to Consumption of Different Sugar Types in Adolescents

Abstract

Cardiovascular disease (CVD) is the leading global cause of mortality and the underlying atherosclerotic disease process which precedes overt CVD originates in youth. Consumption of sugar-sweetened beverages (SSB) are associated with CVD risk factors in youth and SSB intake is a key contributor to added dietary sugar intake in teenagers in the United Kingdom. Endothelial dysfunction is a prerequisite for atherosclerosis and previous research demonstrates that SSB consumption acutely impairs endothelial function. However, these studies have predominantly focused on adult populations, or have used a glucose bolus which is not representative of the sugar found in commercially available SSBs. The purpose of this thesis was to investigate the influence of different dietary sugars found in SSBs on macrovascular and microvascular outcomes and then observe whether the sugar type influences the cardiometabolic responses to a subsequent test meal challenge. This thesis also determined the reliability of measures for the assessment of macrovascular (flow-mediated dilation; FMD) and microvascular (laser Doppler flowmetry) function. Chapter 4: Assessed the within-day and between day reliability of the simultaneous assessment of macrovascular and microvascular function. The within-day and between-day typical error expressed as a coefficient of variation were as follows: FMD, 7.2% and 8.0%; peak reactive hyperaemia (PRH), 24.5% and 26.1%. These results determined that the reliability of outcomes in this study were consistent with existing paediatric data. Chapter 5: There was a large (ηp2=0.27) but not significant (P=0.06) interaction effect for FMD. There was a non-significant difference between the sucrose and control trials for FMD at 1 hour post drink consumption (P=0.06) and 3 hours post test meal consumption (P=0.09) but there was a medium effect at both times with effect sizes of 0.77 and 0.65, respectively, where FMD increased following sucrose consumption. PRH increased 1 hour post drink consumption in the fructose (P=0.01), glucose (P=0.04) and sucrose trials (P=0.04) when compared to control. PRH was greater in the fructose trial when compared to the control (P=0.03), glucose (P=0.01) and sucrose (P=0.02) trials. These findings suggest that SSB intake acutely improves macro- and micro- vascular function in adolescents. Overall, these findings provide important information in regards to the effects of SSBs on macrovascular and microvascular function in adolescents.