Project

hypertension; cardiovascular risk; endothelial dysfunction; autonomic nervous system; Soft drinks; caffeine; fructose; blood pressure; energy drink; autonomic regulation

Lead
Lay summary
Consumption of refined sugars in the form of soft drinks is increasingly recognized as a public health concern with major implications for cardiovascular diseases. This follows many chronic studies in animals suggesting that the fructose component of these added sugars is particularly harmful, contributing to insulin resistance and hypertension. The possibility therefore arises that in humans, the cardiovascular load imposed by ingestion of a single soft drink might, if repeated often enough, have cumulative adverse effects. These adverse consequences might be exacerbated by caffeine, which is often added to soft drinks, particularly in popular 'energy' drinks.We hypothesize that there is a synergistic interaction between low dose caffeine and refined sugars in elevating blood pressure via endothelial dysfunction and autonomic dysregulation, and that this synergistic interaction is even greater with higher doses of caffeine such as those found in commercial 'energy' drinks. To test these hypotheses, we are comparing in healthy young subjects the cardiovascular responses to ingestion of drinks containing fructose, glucose, and sucrose with and without added caffeine, and to assess the role of each sugar compound. In addition, we will also test whether consuming a popular energy drink potentiates the cardiovascular responses to mental effort and physical activity.Our proposed projects should provide important new information in establishing potential mechanisms behind the cardiovascular risk imposed by caffeinated soft drinks and energy drinks. Considering the high levels of consumption of these drinks in the population, and that these studies are designed to simulate 'real-life' consumption of caffeinated soft drinks, the information obtained from this project will have direct impact on public health interest.

Direct link to Lay Summary

Last update: 21.02.2013

Active participation

Number	Title	Start	Funding scheme

Background: Consumption of refined sugars in the form of soft drinks is increasingly recognized as a public health concern with major implications for cardiovascular diseases. This follows many chronic studies in animals suggesting that the fructose component of these added sugars is particularly harmful, contributing to insulin resistance and hypertension. The possibility therefore arises that in humans, the cardiovascular load imposed by ingestion of a single soft drink might, if repeated often enough, have cumulative adverse effects. These adverse consequences might be exacerbated by caffeine, which is often added to soft drinks in doses ranging from 10-15 mg per 100 ml. Although the amounts of caffeine in regular caffeinated soft drinks are generally considered to be ‘low’, our preliminary data suggest that ingestion of 50 mg caffeine, while having little or no impact on cardiovascular responses to water drinking, interacts synergistically with a sugar drink to elevate blood pressure for at least 2 h.Hypothesis: (I)The synergistic interaction between low dose caffeine and refined sugars in elevating blood pressure resides in endothelial dysfunction, autonomic dysregulation and altered blood glucose homeostasis. (II)Consumption of an increasingly popular ‘energy’ drink (containing 80 mg caffeine per can) would also induce an elevation in blood pressure, contributed by endothelial dysfunction, autonomic dysregulation and altered blood glucose homeostasis.(III)Consumption of this popular ‘energy’ drink - which is marketed as a stimulant to be consumed at times of mental and physical activity - would potentiate the cardiovascular load imposed by mental effort and low-intensity physical activity. Objectives & Design: To test these hypotheses, we propose (a) to compare the cardiovascular responses to ingestion of drinks containing fructose, glucose, and sucrose with and without added caffeine, and to assess the role of altered endothelial function, autonomic regulation and glucose metabolism (Project 1), (b) to measure the cardiovascular responses to a popular energy drink, and underlying role of endothelial dysfunction, autonomic dysregulation and altered glucose metabolism (Project 2), and (c) to test whether consuming this popular energy drink potentiates the cardiovascular responses to the mental effort and physical activity (Project 3). We will perform non-invasive beat-to-beat recordings of heart rate, blood pressure, cardiac output and cerebral blood flow. Further evaluation (spectral analysis) of the recorded signals will provide additional information on the underlying autonomic modulation. Microvascular endothelial reactivity will be measured in the skin using Laser Doppler Flowmetry combined with iontophoresis. Blood samples will be withdrawn for measurement of plasma levels of glucose, insulin and caffeine. Potential significance: Our proposed projects should provide important new information in establishing potential mechanisms behind the cardiovascular risk imposed by caffeinated soft drinks and energy drinks. Considering the high levels of consumption of these drinks in the population, and that these studies are designed to simulate ‘real-life’ consumption of caffeinated soft drinks, the information obtained from this project will have direct impact on public health interest.