Investigation of the Cardiovascular Changes - Research Paper Example

Investigation of the Cardiovascular Changes Introduction: In the current advent of innovation and globalization, with shrinking distances and integrated economies, the food industry is also undergoing a paradigm shift. Over the last few decades, concurrent with the increase in popularity of diet/health food and other food fads, there has been an observed rise in the popularity and demand for functional foods, an example of which are energy drinks such as Red Bull (Smit et al., 2004, p. 127; Finnegan, 2003, p. 147). “Energy Drinks” which are so called because they are thought to be stimulant in nature, providing the consumers with an instant boost of energy and alertness and decreasing lethargy and sleepiness, were first introduced in the global market in the late nineties and have been gaining widespread fame ever since[Kim03]. Energy Drinks are categorized as “stimulant drinks,” which have been defined by the Stimulant Drinks Committee as ‘a beverage which typically contains caffeine, taurine and vitamin(s) and may contain an energy source (e.g. carbohydrate) and/or other substance(s), marketed for the specific purpose of providing real or perceived enhanced physiological and/or performance effects [Der03].’ The manufacturers of Energy Drinks claim that such drinks enhance both mental and physical functions, resulting in improved physical endurance, increased alertness and concentration, augmented reaction speed and an elevated affect[Kim03]. Statistics reveal that the United States ranks as the largest consumer of energy drinks worldwide with an annual consumption amounting to approximately 290 million gallons (Weise, 2008 cited in Higgins et al., 2010, p. 1033). It is interesting to note that the age group in which the consumption of such drinks is the highest is between 11-35 years (Ballard et al., 2010 cited in Higgins et al., 2010, p. 1033). Such drinks are common amongst the adolescent age group, in particular, amongst students due to a variety of reasons including the perception that these drinks help to boost one’s performance especially during athletic performances and during exams, help in overcoming fatigue and sleepiness and also because such drinks have now become a fad nowdays and are widely available during parties and other social gatherings[Rus08]. There are several varieties of Energy Drinks available commercially and amongst them, Red Bull is one of the most famous and commonly consumed Energy Drink. The key active ingredients of this drink include caffeine (approximately 32 mg/dL), taurine (approximately 400 mg/dL or 1000 mg per drink), glucuronolactone (approximately 240 mg/dL or 600mg per drink), and sugar (as an energy source)[Kim03]. In addition, these drinks also contain water and small quantities of some vitamins and minerals[Fra10]. Amongst the active ingredients, caffeine and taurine are found to contribute most significantly towards the aforementioned positive effects. An important component of energy drinks is carbohydrates which are present in significant amounts in the form of in concentrated forms of sugars such high-fructose corn syrup or sucrose. It is a well known fact that carbohydrates are the major energy metabolites of the human body. Studies have revealed that administration of moderately concentrated solutions of carbohydrates, or amounts between 25-50 g of glucose, help in improving exercise capacity and delay the occurrence of post-exercise fatigue (Scholey & Kennedy, 2004; Higgins et al., 2010). In addition, consumption of glucose in levels similar to those present in Energy Drinks has been found to improve cognitive functions including attention and reaction times (Smit et al., 2004). On the other hand, caffiene which is the other key active component of Energy Drinks, is known to be a central nervous system stimulant. Caffiene has been found to exert several important effects throughout the human body, including and not limited to activation of the sympathetic adrenal–medullar system, elevation of blood pressure during states of stress such as exercise, increase in the metabolic rate and various cognitive effects such as increased subjective feelings of well being and alertness, enhanced arousal and improved reaction times (Smit et al., & Rogers, 2004, p. 127; Smit & Rogers, 2002). The multiple effects of caffeine on the central nervous system are thought to occur as a result of blockade of adenonsine receptors by caffeine, which via increases in the levels of cAMP disinhibits the cholinergic neurons in the central nervous system, resulting in pervasive excitatory responses (Adler, 2000 & Buam and Weiss, 2003, cited in Kim, 2003, p. 4). With regard to the cardiovascular system, laboratory studies have revealed that caffeine induces reflex bradycardia via vagal stimulation[Fra10]. Studies have revealed that ingestion of more than 200 mg of caffeine can lead to several adverse effects such as palpitations (due to arrhythmias and tachycardia), anxiety, insomnia headache and nausea (Higgins et al., 2010). Similarly, Taurine (2-aminoethanesulphonic acid), another important component of Energy Drinks is a naturally occurring amino acid found in the human body which is produced predominantly in the liver and the brain. It is known to be neuroprotective in nature, plays a role in muscle contraction and also has osmoregulatory functions (Seidl et al., 2000; Kang, et al., 2002 cited in Kim, 2003, p. 2). Taurine has also been found to have an impact on the cardiovascular system; it causes the supression of the sympathetic nervous system, and also plays a role in the mobilization of calcium stores in cardiac muscle cells during ischemic events[Fra10]. Effects of energy drinks on the cognitive performance: As discussed above, several components of Energy Drinks have been shown to have stimulatory effects on the central nervous system leading to improvement in cognitive performance, alertness and concentration. This section reviews the various studies that have been conducted in order to conclusively elucidate the effects of the various active components of the Energy Drinks on cognitive performance either in isolation on in conjugation with each other. Several studies have been conducted in the past in order to determine the effects of either glucose or caffeine on the cognitive performance and mood of the subjects and have revealed that both these substances help in improving cognitive performance and mood, including the level of alertness, reaction times and attention span (Kennedy & Scholey, 2000 and Rogers & Dernoncourt, 1998 cited in Kennedy & Scholey, 2004, p. 331). However, there is a paucity of data on the combined effects of these substances on an individual’s cognition. Kennedy and Scholey (2004) reported that consumption of drinks containing a combination of caffeine and glucose resulted in improved cognitive performance, as assessed by the performance on Rapid Visual Information Processing task (RVIP), and lower levels of mental fatigue[Dav042]. Moreover, it was also noted that with higher concentrations of caffeine the levels of mental fatigue were lower, which suggests a possible dose-response relationship[Dav042]. Thus, the authors concluded that the combination of caffeine and glucose was effective in improving attentiveness and concentration and also helped in mitigating the subjective feeling of fatigue[Dav042]. Similar findings found via other studies (Smit et al., 2004, p. 127; Smit & Rogers, 2002, p. 324). Similarly, Specterman (2005) noted increased corticospinal tract activity amongst subjects after the administration of a drink containing both caffeine and glucose, as determined by the measurement of motor-evoked potentials (MEPs) produced in response to transcranial magnetic stimulation (TMS) of the motor cortex (Specterman et al., 2005, p. 726). Moreover, it was found that the sum of the individual effects of caffeine and glucose was not simply additive in nature. Infact, the sum was found to be much larger than the effect which suggests that there is a potential for saturation of the excitability potential of the synapses involved (Specterman et al., 2005, p. 726). However, further studies need to be conducted in this regard in order to obtain conclusive evidence to support this postulation. In the same way, a combination of caffeine and taurine has been proven to enhance one’s concentration and reaction speed and also promote feelings of wellbeing in the individual (Seidl et al., 2000 cited in Kim, 2003, p. 3). It has been postulated that the stimulatory effects of taurine on the central nervous system may be due to the interactions of this substance with the GABAergic, glycinergic, cholinergic and adrenergic neurotransmitter systems (Alford et al., 2001, p. 147). However, the synergistic effect of caffeine and taurine is still debatable, and whether the stimulatory cognitive effects of Energy Drinks result from the combined actions of caffeine and taurine or due to caffeine alone, stills remains to be elucidated. Thus, it is clear from the above mentioned discussion that the various ingredients present in Energy Drink, including carbohydrates, caffeine and taurine have a variety of positive cognitive effects, including boosted alertness, improved reaction times and elevated mood. Effects of energy drinks on the cardiovascular performance: Ever since the introduction of Energy Drinks there have been a handful of incidences of adverse events and mortality resulting from the cardiovascular side effects, such as ventricular tachycardia and other arrhythmias, of Energy Drinks[Der03]. These occurrences resulted in concerns arising regarding the safety of these drinks and the effects of Energy Drinks on the cardiovascular system. This section examines the various cardiovascular effects of energy drinks. The consumption of Energy Drinks containing caffeine and taurine has been shown to enhance ventricular function, resulting in an increase in stroke volume and diastolic inflow velocity (Baum & Weiss, 2001 cited in Kim, 2003, p. 2). A study conducted by Baum and Weiss (2001) revealed that in addition to improvement in ventricular function, energy drinks play a role in enhancing the contractility of the left atrium, which was gauged by using echocardiography[Fra10]. This increase in left atrial contractility leads to an increased end-diastolic volume in the left ventricle which contributes towards the observed increase in stroke volume[Fra10]. However, in this study, no significant alterations in blood pressure were found (Baum & Weiss, 2001 cited in Ragsdale, et al., 2010, p. 1194). In addition to enhancing atrial contractility and increasing stroke volume, the components of Energy Drinks, including caffeine and taurine have been shown to cause an increase in diastolic blood pressure (Alford et al., 2001, p. 146). Moreover, it has also been found that during states of physiological stress, such as exercise, energy drinks help in mitigating the expected alterations in blood pressure and also help in pain modulation, resulting in increased pain tolerance[Fra10]. Although the improvement in left ventricular functioning and the increase in blood pressure observed after the administration of Energy Drinks is well documented in literature, there is inconclusive evidence regarding the effect of Energy Drinks on the heart rate. While most studies report that the components of Energy Drinks result in decreases in the heart rate [Fra10], there have been reports of increased heart rate being observed after consumption of Energy Drinks (Alford et al., 2001, p. 146). Thus, findings from literature suggest that the active ingredients in Energy Drinks such as caffeine and taurine have numerous effects on the cardiovascular system including an increase in diastolic blood pressure, increase in stroke volume and possible alterations in heart rate. Moreover, it has also been established, that the consumption of moderate amounts of Energy Drinks, such as a single can of Red Bull at a time, is safe and does not have any significant cardiovascular adverse effects[Fra10]. Rationale: Although extensive research has been carried out in the past to determine the effects of the various components of Energy Drinks on the cardiovascular and cognitive performances of individuals, till date, there is a paucity of studies comparing the differences in these outcomes with the administration Energy Drinks with and without the sugar component. The current study, thus, aims at elucidating the effects of Energy Drinks on the cognitive and cardiovascular performances of students during a lecture. Moreover, it also aims to compare the differences in these effects amongst individuals who consumed the Energy Drink with the sugar component as compared to those who consumed the drink without sugar, so that the role played by the different constituents of the energy drinks such as caffeine and carbohydrates can be determined. Figure 1: Comparison of various commercially available energy drinks (adapted from Heneman & Zidenberg-Cherr, 2007) References Adler, GK. (2000) Exercise and fatigue--is neuroendocrinology an important factor? Journal of Clinical Endocrinology and Metaolism,85, 2167-9. Alford, C., Cox, H., & Wescott, R. (2001). The effects of Red Bull Energy Drink on human performance and mood. Amino Acids , 139-150. Baum, M. & Weiss M. (2001). 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