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Effects of energy drink major bioactive compounds on the performance

The consumption of beverages containing caffeine and taurine before exercising has been associated with increased physical and psychological performances and has been promoted to support the emotional state and provide vitality to consumers. However, there are contradictory results on these issues, it is not clear the effect of every major compound in relation to the whole effect of the beverages and there is a lack in knowledge about their degree of safety for consumption.

This study used a double-blind, placebo controlled, randomized, crossover design. Fourteen male volunteer soldiers from the Colombian army performed different tests to measure their cardiorespiratory fitness (VO2max and maximum heart rate), time to exhaustion, strength (isometric strength), power (vertical jump), concentration (Grid test) and memory (Digits test) after drinking 250 ml of one of the following beverages: one with 80 mg caffeine, one with 1000 mg taurine, one with 80 mg caffeine plus 1000 mg taurine, a commercial energy drink (Red Bull®) or a placebo drink. Subjects were caffeine-consumers that avoided caffeine during the day of evaluation. All beverages were matched in flavor and other organoleptic properties to the commercial one, were bottled in dark plastic bottles and were administered in identical conditions to the participants. Differences between treatments were assessed using repeated measures and analysis of variance.

Energy drinks are soft drinks, generally carbonated, composed of different ingredients such as caffeine, taurine, glucuronolactone, carbohydrates and vitamins with different rates of absorption to which the proposed effects of these beverages are attributed [1-3]. Furthermore, depending on the brand, these solid drinks have other ingredients such as amino acids, minerals and vegetable extracts, together with acidulants, preservatives, flavorings and colorings. These types of products have gained popularity worldwide since the 1990s, increasing exponentially the consumption among adolescents, athletes, and even senior citizens [4]. Manufacturers of these products promote their consumption with statements offering a variety of benefits among which increased physical performance, improved reaction rate, increased attention, higher concentration, improved emotional state and weight loss are included [4]. These are desirable characteristics for anyone, especially for active individuals. The interaction of the major bioactive compounds has been proposed as responsible for the alleged effects of these products; however, such statements have not been well studied and are not fully supported. Furthermore, there are contradictory results on the issue. Some studies attribute the alleged effects in improving the state of concentration and physical endurance to the combination of the compounds that make up these products [5,6]. Other studies point out that is very likely that most of the observed effects after consumption of these drinks are mainly produced by caffeine [7-9]. On the contrary, other studies have found no increase in the performance after consumption of these collagen peptide drinks [10].

Currently, many people seek benefits for their physical and mental health situation that has led them to use these types of meal replacement drink; nonetheless, despite an increased consumption by the general population, there is a lack of knowledge about the physiological effects of the compounds used in the formulations, the level of security in their consumption and their position within food standards. This is probably because there are few well-designed studies that provide accurate and conclusive findings on the subject.

Therefore, in this study we evaluated the efficacy and safety of energy drink consumption in a randomized, controlled, double-blinded, crossover trial and thus we were able to assess the direct involvement of caffeine and taurine, as major bioactive compounds of energy drinks, on physical and cognitive condition in young adults.

A sample of 9 or 13 subjects was calculated in order to find differences in cognitive or physical tests. This was done by using PRIMER software 3.02 (PRIMER-E Ltd, United Kingdom), after establishing a confidence level of 95% and a power of 80%. Nonetheless, 14 volunteered male soldiers, members of the National Army of Colombia Seventh Division, were included in the study. No cigarette smokers or users of psychoactive substances, or subjects under any medication (e.g. beta blockers) were included. People who consumed more than 600 ml of coffee or more than 5 units of colas per day were excluded [11].

All participants underwent a complete physical examination and an electrocardiogram to determine their physical and mental conditions and all were diagnosed as healthy. In addition, they all signed the informed consent before the physical and cognitive tests. The procedures performed were endorsed and approved by the Indeportes Antioquia Research Committee and the National Army Research Committee in order to provide protection to the study participants.

Experimental design

This research used a double-blind, placebo controlled, randomized, crossover design, in which each participant visited six times the Exercise Physiology Laboratory from Indeportes Antioquia, in Medellín, Colombia, at 1540 m above sea level. Three fitness tests and two cognitive condition tests were applied in each visit. All evaluation sessions were separated between 48 or 72 hours and three subjects were evaluated per day. In the first session the subjects performed the tests, without drink consumption, to become familiar with their development. Testing was always conducted at the same time (2 pm-5 pm) in an environment with controlled temperature and humidity of 25°C and 60%, respectively. A training specialist and a psychologist with extensive experience in sports fields were responsible for measuring all variables.

Participants maintained their regular food intake, workplaces and recreational activities during study participation, but did not train at high intensity eight hours before the tests, did not eat heavy meals two hours before the tests and avoided caffeine consumption during the day of evaluation. Since the participants were soldiers, they had a very controlled schedule regarding food and exercise every day. So we are sure that during the day of evaluation the variation in these variables was kept to the minimum. All subjects used appropriate clothing for physical exercise.

Before developing the tests all subjects were randomly assigned (with the help of Excel 2007, Microsoft Co, USA) to a treatment (a placebo drink, a caffeinated drink, a caffeine and taurine combined drink, a drink with only taurine, or a commercial energy drink) and after 45 minutes performed each of the tests. All subjects received all beverages during the study. The composition of the five beverages is illustrated in Table 1.

Functional beverages play an essential role in our modern life and contribute to nutritional well-being. Current efforts to understand and develop functional beverages to promote health and wellness have been increased. Determining bioactive compounds out of the food content and incorporating them into beverage requires a thorough knowledge. Functional foods have lower or no adverse effects like current drug treatments and are good candidates for this purpose. Functional food treatment is a complementary approach for the prevention and treatment of several systemic diseases and they are tailored for individual’s choice for boosting energy, shrinking waistlines, and mental focusing. Further, functional foods with lifestyle modifications may lead to wellness and improve individual’s health. Functional foods may include but not limited to fruits, fiber-enriched grains, and beverages. Experiments on animal research monitor improvements but translational research must be performed to reduce and/or prevent systemic diseases. Beverages can meet individual’s demand and nutrients as well as bioactive compounds can be delivered conveniently. This review summarizes current knowledge of bioactive compounds and scientific advances at functional beverages.

Soft drinks consumption is still a controversial issue for public health and public policy. Over the years, numerous studies have been conducted into the possible links between soft drink intake and medical problems, the results of which, however, remain highly contested. Nevertheless, as a result, increasing emphasis is being placed on the health properties of liquid drinks, by both the industry and the consumers, for example, in the expanding area of functional prebiotic compound drink. Extensive legislation has been put in place to ensure that soft drinks manufacturers conform to established national and international standards. Consumers trust that the soft drinks they buy are safe and their quality is guaranteed. They also expect to be provided with information that can help them to make informed decisions about the purchase of products and that the information on product labels is not false or misleading. This paper provides a broad overview of available scientific knowledge and cites numerous studies on various aspects of soft drinks and their implications for health safety. Particular attention is given to ingredients, including artificial flavorings, colorings, and preservatives and to the lesser known risks of microbiological and chemical contamination during processing and storage.
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