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Energy-drink consumption in college students and associated factors
Nutrition 27 (2011) 316–322
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Applied nutritional investigation
Energy-drink consumption in college students and associated factors Sema Attila Ph.D. *, Banu Çakir M.D., M.P.H., Ph.D. Department of Public Health, Hacettepe University Faculty of Medicine, Ankara, Turkey
a r t i c l e i n f o
a b s t r a c t
Article history: Received 26 October 2009 Accepted 11 February 2010
Objective: To investigate the frequency of energy-drink consumption and associated factors in a group of college students. Methods: A cross-sectional study was conducted in Hacettepe University (Ankara, Turkey) and included 439 students pursuing a career in medicine, sports, and arts. Only fourth-year students were approached. Data were collected using a self-administered standard questionnaire. Results: In bivariate analyses, frequency of energy-drink consumption was higher in students of arts and sports and in those who did not have breakfast on a regular basis, ever smoked cigarettes, drank alcoholic beverages, and regularly engaged in sports compared with their counterparts. Many students who had ‘‘ever’’ tried an energy drink did so the first time because they wondered about its taste. Of regular users of energy drinks, reasons for using such drinks varied across the three selected groups of students and included obtaining getting energy, staying awake, boosting performance while doing sports, or mixing with alcoholic beverages. About 40% of all current users of energy drinks reported that they mixed those with alcoholic beverages. In multivariate analyses, statistically significant predictors of energy-drink consumption were faculty type, presence of any health insurance, use of alcoholic beverages, and monthly income, controlling for gender. Most students could not correctly define the ingredients of energy drinks or their potential hazardous health effects, and they could not distinguish energy and sports drinks when they were requested to select them from a list of commercial names of various drinks. Conclusion: Consumption of energy drinks, despite the variation in the reason for choosing such drinks, is quite common in college students. Awareness of university students of the ingredients and potential health hazards of energy drinks, in particular in mixing with alcoholic beverages, should be increased. Ó 2011 Published by Elsevier Inc.
Keywords: Energy drinks Young adults College students
Introduction Fluids are a vital requirement for humans, but fluid intake can be obtained from a variety of fluid sources other than water. The selection of appropriate fluids, timing of the intake, and supplement choices are important for optimal health, especially in young people. The Beverage Guidance Panel, initiated by Popkin et al. [1] aims to provide guidance on the relative health and nutritional benefits and risks of various beverage categories. Popkin et al. [1] reported that in the United States daily calorie intake has recently increased about 150–300 kcal, with approximately 50% of the increase coming from the consumption of sweetened beverages. Although still a relatively small proportion in total fluid intake, the absolute rate of energy-drink use has been * Corresponding author. Tel.: þ90-312-305-1590; fax: þ90-312-311-0072. E-mail address: [email protected] (S. Attila). 0899-9007/$ - see front matter Ó 2011 Published by Elsevier Inc. doi:10.1016/j.nut.2010.02.008
increasing significantly, especially in young individuals. Energy drinks are beverages (e.g., Red Bull, Venom, Burn, and Adrenaline Rush) that contain large doses of caffeine and other legal stimulants such as taurine, carbohydrates, glucuronolactone, inositol, niacin, panthenol, and b-complex vitamins. Hundreds of different brands on the market have high caffeine content, ranging from a modest 50 mg to an alarming 505 mg per can or bottle [2]. Energy drinks have been found to improve attention and/or reaction times and indices of alertness in some studies; the combination of caffeine and glucose can ameliorate deficits in cognitive performance and subjective fatigue during extended periods of cognitive demand. However, several ingredients of energy drinks, with sucrose and caffeine taking the lead, may have unwanted health consequences in youngsters and should be used carefully. Energy drinks have stimulating properties that can boost heart rate and blood pressure, dehydrate the body, may aggravate the effects of other stimulants, and prevent sleep.
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Unlike sports drinks (the use of which is supported for athletes), energy drinks should not be used while exercising because the combination of fluid loss, sweating, and the diuretic quality of the caffeine can leave the user severely dehydrated [2–5]. Such drinks are widely consumed by young people, by college students, in particular, for a variety of reasons. Even more important from a public health point of view, international studies have indicated that mixing energy drinks with alcohol is fairly frequent among college students [6–8]. Mixing energy drinks with alcohol may be dangerous given the stimulant nature of energy drinks and depressant characteristics of the alcohol. The stimulant effect can mask how intoxicated a person is and prevent individuals from realizing how much they drink. The stimulated person seems alert and even companions cannot recognize ‘‘whether the person had enough alcohol’’: the blood alcohol concentration would be the same as in others; and as the stimulant effect wears off, the depressant effects of alcohol will become prominent, a person may vomit and even have respiratory depression. Moreover, alcohol and energy drinks are very dehydrating and together will hinder the body’s ability to metabolize alcohol and further increase the toxicity of alcohol [2,3,9,10]. Although energy drinks are mainly targeted to young adult consumers, there has been little research regarding effects of energy-drink consumption by college students and the potential for related health hazards [6,7,9,11]. Observations have suggested that young adults can easily access energy drinks and use energy drinks frequently, but there is scarce evidence on the reasons why they consume energy drinks and whether they are aware of the potential health hazards. This study examined the frequency of consumption of energy drinks in a group of university students selected from different faculties, who were hypothesized to have different consumption habits, and investigated the factors for preferring such drinks. The study also examined students’ level of knowledge on ingredients and on potential health hazards of energy drinks. Last but not least, we reviewed related international work to compare and contrast local findings to encourage further discussion on the importance of energy-drink consumption in college students from a public health perspective and to brainstorm for potential interventions for the future. Materials and methods A cross-sectional study was conducted in students attending three colleges of Hacettepe University (Ankara, Turkey). It is important to note that the study aimed primarily to calculate consumption rates in various faculties, being mainly descriptive in nature, with no specific a priori hypotheses, but with an ultimate objective of screening/generating some hypotheses on potential risk factors of energy-drink consumption and related patterns (if any) [12]. School selection was based on the likelihood of energy-drink use by students. Students from the Faculty of Medicine (FoM), College of Sports (CoS), and College of Arts (CoA) were approached because these students were likely to use energy drinks to stay awake for studying or during night calls in the hospital; to boost their performance in exercising; and to be exposed more to energy drinks in social gatherings, activities, plays, etc., respectively. To eliminate the potential confounding effect of age, the study group was restricted in the planning stage to final year (fourth year) students of the CoS and CoA and fourth-year students of the FoM [12]. All students attending classes on the day of data collection were approached and included in the study if they agreed to participate. The study included 439 students, with 254 (57.9%), 94 (21.4%), and 91 (20.7%) students from the FoM, CoA, and CoS, respectively. More than 95% of all students approached took part in the study; however, completion rates of the total number of registered students of the selected schools stayed below 80%, given low attendance rates to classes, being out of school due to practical training in the field, etc. Data were collected via a self-administered, standard, pretested questionnaire. The questionnaire consisted of 35 questions on students’ sociodemographic characteristics, personal habits, total fluid intake, energy-drink–related knowledge, and habits.
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Written approval was obtained from each faculty’s administrators before research, and verbal (informed) consent was received from each participant. Participation was totally voluntary and no incentives were provided to participants. In the study, students were first asked whether they had ever used any energy drinks. Later, they were given a list of beverages available in the market, including energy drinks, sports drinks, and soft drinks. They were requested to mark which of those they tried at least once. Once they answered this question, a standard definition was provided to them to explain what was meant by an ‘‘energy drink.’’ In the study, energy drinks were defined as ‘‘drinks that provide energy due to carbohydrates in composition and include legal vitamin and minerals in specified amounts,’’ as defined by the Turkish Nutrition Codex [13]. Later, they were asked again whether they had ever used such a drink. Distributions of ‘‘energy-drink use’’ and discussed throughout this report are based on this second question, according to a standard definition and thus were considered to be more robust. Of note, our comparison of the number of reportedly ‘‘ever users of energy drinks’’ matched quite well with the number of students who checked at least one of the energy/sports drinks in the provided list of beverages.
Statistical analysis Statistical analyses included frequency and percentages of distributions. The status of knowledge on ingredients and potential health hazards of energy drinks was comparatively studied for ‘‘ever’’ users of energy drinks versus among all study participants. An exploratory analysis was performed to model significant predictors of energy-drink consumption (ever users versus never users). Gender, age (22 and >22 y, i.e., the median age), family type (nuclear versus other), place of residency (with family/siblings versus other), possession of health insurance (any versus none), monthly income, educational attainment of the mother (higher than secondary school versus below), educational attainment of the father (higher than secondary school versus below), sleeping habits (regular versus irregular), cigarette smoking (ever versus never), alcohol use (ever versus never), presence of at least one ‘‘risk-taking behavior’’ having breakfast (regular versus irregular/none), and doing sports (regular versus irregular/none; the latter two were used as surrogate measurements for ‘‘healthy behavior’’) were checked for their potential associations with energy consumption because these were the factors identified in previous studies as being associated with energy-drink consumption and/or as potential confounders. A backward elimination logistic regression modeling technique was used to reach the most parsimonious yet statistically significant model. Gender was added to the final model to make the final model comparable to those obtained from other studies that were/could be conducted elsewhere.
Results The study included 439 college students, with ages from 19 to 39 y, with a mean standard deviation of 22.8 2.09 y (median 22 y). Distribution of age was quite homogenous in the FoM group, but varied widely in the CoA group. Table 1 presents the distribution of sociodemographic characteristics of study participants. Of the group, more than half were students in the FoM (n ¼ 254), 94 students were from the CoA, and 91 students were from the CoS. The study aimed to include fourth-year students in all three schools; however, in the CoA and CoS, some students (<5%) from lower classes were included in the study because they took the selected class on the day data were collected. Of the study participants, 91.3% were from nuclear families of a middle-to-high cultural level (80.2% of fathers and 62.6% of mothers had at least a high school level education; 38.0% of fathers and 22.8% of mothers had science-related occupations). About half of students used to live with their parents, and only 9.1% were living alone. Of the students, 13.4% reported that they had no health insurance and the rest had some sort of health insurance. Students were asked to report the average monthly income that ‘‘they spend for their personal needs’’ (excluding rent, school fees, etc.): the average monthly income of the group corresponded to the minimum legal income of a worker in Turkey, which was quite adequate for a student.
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The study collected data on personal habits of the study participants that could be associated with energy-drink use. Table 2 presents the distribution of some personal habits of study participants. Based on students’ self-reports, 45.1% used to have regular sleep patterns, with an average period of 7.23 1.31 h/d. Of all students studied, 64.0% had never tried smoking, whereas 26.9% were current smokers: average pack-years of cigarette smoking were 2.25 1.74 in ever-smokers and 3.94 2.86 in current smokers. Thirty-six percent of students (n ¼ 159) had never tried alcohol, and of the drinkers, more than 75% reported that they drink alcohol less than once a month. Students were asked to report whether they engaged in any of the following six behaviors and the frequency of risk takers were calculated for these risk-taking behaviors: ‘‘not using a seat belt’’ (37.8%), ‘‘driving fast’’ (26.2%), ‘‘driving under the influence of alcohol’’ (6.4%), ‘‘unsafe sex’’ (13.9%), ‘‘carrying guns/weaponry’’ (6.4%), and ‘‘applying violence against friends’’ (7.1%). In the group, 63.6% reported that they did sports regularly; because one-fourth of the study participants were from the CoS, this question did not provide much information. Half the students reported that they regularly have breakfast on a daily basis and more than half of the students used to regularly have at least three meals a day. Only 10% of students reported having a chronic
Table 1 Distribution of sociodemographic characteristics of study participants (n ¼ 439) Characteristics Gender Male Female Age groups (y) 20 21–24 25 Family type Nuclear Extended Other Shares residency with Parents and/or siblings Friends Lives in dormitory Lives alone Social insurance Governments Employee Retirement Fund Social Security Association Bag-Kur Private insurance Green Card None Monthly income used for personal requirements (YTL) <250 250–499 500–999 1000 Educational attainment of mother Literate/illiterate (no schooling) Primary school graduate Middle school graduate High school graduate College/university graduate (including postgraduate degrees) Educational attainment of father Literate/illiterate (no schooling) Primary school graduate Middle school graduate High school graduate College/university graduate (including postgraduate degrees)
No.
Percentage
222 217
50.6 49.4
28 315 60
6.4 79.9 13.7
401 31 7
91.3 7.1 1.6
215 123 61 40
49.0 28.0 13.9 9.1
219 102 42 16 1 59
49.9 23.2 9.6 3.6 0.2 13.5
104 195 124 16
23.7 44.4 28.3 3.6
10 56 21 107 245
2.2 12.8 4.8 24.4 55.8
21 116 27 131 144
4.8 26.4 6.2 29.8 32.8
Table 2 Distribution of some personal habits of study participants Characteristics Sleeping habits Regular Irregular Daily sleeping hours (on average) 6 7 8 9 Cigarette smoking Never smoked Quitters Current smokers Alcohol use Never Ever Risk-taking behaviors* Not use safety belts Drive cars fast Drive under influence of alcohol Unsafe sex Carry guns/weaponry Violence to/from friends Doing sports Regular Irregular/none Having breakfast Regularly Irregularly Never
No.
Percentage
198 241
45.1 54.9
116 138 137 48
26.5 31.5 31.2 10.8
281 40 118
64.0 9.1 26.9
159 280
36.2 63.8
166 115 28 61 28 31
37.8 26.2 6.4 13.9 6.4 7.1
160 279
36.4 63.6
229 176 34
52.2 40.1 7.7
* Percentages were calculated from 439. Given that more than one risk-taking behavior can be present, totals do not sum to 100.0.
disease and the most commonly reported three conditions were depression, migraine, and asthma. The study also investigated whether energy-drink use in young adults is associated with general health status, habits, and/or risk-taking/healthy lifestyle behaviors; Table 3 presents related findings of energy-drink use and related behaviors in study participants. The most commonly preferred drink was water and almost half of study participants reported that they drink at least five glasses of water per day. Of the students, 48.3% (n ¼ 212) had ever tried an energy drink (Table 3). The most common reason to try an energy drink was ‘‘curiosity of its taste/effects’’ (48.3%), followed in order of frequency by ‘‘for energy’’ and ‘‘to boost performance.’’ About one-third of students who had never tried an energy drink reported no specific reason for that, 36.1% reported that they did not wonder about its taste, whereas 19.4% had not tried an energy drink before because they considered such drinks ‘‘unhealthy.’’ Sixty percent first used these drinks during their college years, with the most common places for a first try being ‘‘home’’, ‘‘recreational areas,’’ and ‘‘bars.’’ Most often, the students had tried their first energy drink in the company of a ‘‘friend.’’ Of current users of energy drinks (n ¼ 145), most did so to ‘‘get energy’’ or ‘‘to boost their performance in doing sports’’ and only 9.7% used energy drinks with meals. About half of ‘‘current’’ energy drinkers used such drinks in recreational areas while doing sports and about one-third did so in bars (Table 4). The distribution of answers to questions inquiring about students’ knowledge of the ingredients and potential health hazards of energy drinks is presented in Table 5. Only one-third of all participants and a little more than half of ‘‘ever’’ drinkers of energy drinks reported that they ‘‘knew’’ the ingredients of energy drinks. However, the most commonly reported
S. Attila, B. Çakir / Nutrition 27 (2011) 316–322 Table 3 Energy-drink use and related behaviors among study participants Characteristics Use of energy drinks Ever Never Main reason for NOT trying energy drinks (n ¼ 227) No particular reason No ‘‘curiosity’’ to try Think them as ‘‘unhealthy’’ Not aware of ingredients High calories Not need energy Expensive Think them as ‘‘addictive’’ Main reason for using energy drinks (n ¼ 201) Wondered its taste To feel ‘‘energetic’’ To boost performance during exercise To mix with alcohol To stay awake for long hours To boost performance while reading/studying Timing of first experience with energy drinks (n ¼ 197) In secondary school In high school In college/university Place where first tried an energy drink (n ¼ 201) At home Doing sports (in recreational areas) Bar In the street Coffee shop In dormitory Other places Not remember Any companion when first tried an energy drink (n ¼ 201) None Friend(s) Family members Boy/girlfriend
No.
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Table 4 Energy-drink use behaviors among ‘‘current’’ users of energy drinks (n ¼ 145) Percentage
212 227
48.3 51.7
84 82 44 6 4 4 2 1
37.0 36.1 19.4 2.6 1.8 1.8 0.9 0.4
98 32 30 24 10 8
48.3 15.9 14.9 11.9 5.0 4.0
9 76 122
4.3 36.8 58.9
49 48 29 24 21 8 8 14
24.4 23.9 14.4 11.9 10.4 4.0 4.0 7.0
59 119 12 11
29.4 59.2 6.0 5.4
ingredients are sugar and caffeine, and most students did not correctly mark the other ingredients given in multiple choices (Table 5). It is important to note that 37.2% of students reported that they mixed energy drinks with alcohol, whereas 62.8% of ‘‘ever’’ users had never done so. As presented in Table 5, almost half the students who reported that they knew the health effects of energy drinks and reported the source of their knowledge learned about the effects of energy drinks in classes and/or educational materials provided in schools. Media messages were reported as the major source of information on energy drinks by one-third of the students. One of every five students reported that they learned about energy drinks from their friends/peers. In binary analyses, ‘‘ever’’ use of energy drinks (versus never users) was found to be statistically significantly associated with the type of school, health insurance, smoking, alcohol use, and doing sports. Binary analyses also suggested that students with a higher monthly income were more likely to use energy drinks than their counterparts with a lower income (Table 6). Table 7 presents the final logistic regression model for energy-drink consumption by study participants (ever users versus never users). Logistic regression modeling of energydrink use (ever drinking versus never drinking) indicated that, controlling for age, men were 1.5 times more likely than women
Characteristics Frequency of energy-drink use >2 bottles/d 2 bottles/d 1 bottle/d <1 bottle/d Type of energy drink preferred* Red Bull Powerade Burn Other (Gatorade, Red Devil, Shark) Unspecified Reasons for using energy drinks* To feel ‘‘energetic’’ To boost performance during exercise For its taste Use in cocktails, mixed with alcohol To concentrate while studying To stay awake No specific reason Relation to regular meals Drink with meals Not drink with meals With or without meals Place where energy drink is consumed* Recreational areas Bars At home Coffee shop In dormitory In campus *
No.
Percentage
2 5 8 130
1.4 3.4 5.5 89.7
75 30 29 4 7
51.7 20.7 20.0 2.8 4.8
35 31 26 22 13 11 7
24.2 21.4 17.0 15.2 8.9 7.6 4.8
131 10 4
90.3 6.9 2.8
68 47 45 32 30 19
46.9 32.4 31.0 22.1 20.7 13.1
Percentages were calculated from 145.
to use energy drinks; alcohol drinkers were 2.5 times more likely to use energy drinks than alcohol non-users; and students of the CoA (2.5 times) and CoS (9.2 times) were more likely than medical students to ever taste energy drinks. Having no health insurance (a surrogate measurement for low socioeconomic status) was also positively and significantly associated with energy-drink use. Students with reportedly higher monthly incomes were more likely to try energy drinks than their counterparts with lower incomes.
Discussion The energy-drink market has grown exponentially over the past decade. The absence of regulatory oversight in many countries has resulted in aggressive marketing of energy drinks over the world, targeted primarily toward young adults (men in particular). Using energy drinks is a popular practice among college students for a variety of situations: to compensate for insufficient sleep, to increase energy, while studying, while driving for long periods, drinking with alcohol while partying, and to treat a hangover. Some previous work suggested that young people may use energy drinks as ‘‘natural alternatives’’ to other fluids, ‘‘to boost performance and concentration,’’ ‘‘to stay awake before exams,’’ ‘‘to mix with alcoholic beverages to improve the taste,’’ etc. [2,8,14,15]. Almost all these reasons were mentioned as the underlying factor for ‘‘trying/using energy drinks’’ in our study population. In addition to the frequency of an agent, the associated burdens of morbidity and mortality determine its significance as a public health concern. Although energy drinks are targeted to young adult consumers, there has been little research regarding
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Table 5 Energy-drink–related knowledge by study participants Characteristics Having knowledge on ingredients of energy drinks, based on self-reports Among all study participants (n ¼ 439) Among those who have ‘‘ever’’ used an energy drink (n ¼ 212) Source of knowledge on health hazards of energy drinks (n ¼ 128) Classes in school Visual media Friends Written media Other (not specified)
Table 7 Logistic regression model for ‘‘ever’’ use of energy drinks
No.
Percentage
128 116
29.2 54.7
44 21 18 11 34
34.4 16.4 14.1 8.6 26.5
the health effects of energy-drink consumption by college students. Clauson et al. [3] recently published a review article on the benefits and adverse effects associated with the consumption of energy drinks. Based on data from searches for published articles written on energy drinks, the investigators concluded that most energy drinks contain natural products and that amounts of guarana, taurine, and ginseng found in popular energy drinks are far below the amounts expected to deliver therapeutic benefits or adverse events. However, caffeine and sugar are present in amounts known to cause a variety of adverse health effects. Caffeine in the quantities present in most energy drinks may lead to insomnia, nervousness, headache, tachycardia, and seizures [3,16]. In children and adolescents who are Table 6 Knowledge of study participants about ingredients and health hazards of energy drinks Characteristics
Ingredients of energy drinks, as chosen by study participants from given choices Sugar Caffeine Salt and minerals Vitamins Carbon dioxide and other gases Doping agents Citric acid Taurine Protein Alcohol Nicotine Effects of energy drinks as reported by study participants Hazardous for heart Decreases sleeping hours Provides energy Supplies water and minerals No beneficial effect on health Addictive Causes obesity Causes depression Causes insulin resistance Causes peptic ulcer * y
All participants (n ¼ 439)
‘‘Ever’’ users of energy drinks (n ¼ 212)
No.
Percentage*
No.
Percentagey
214 171 139 130 105
48.7 39.0 31.7 29.6 23.9
149 121 103 98 77
70.3 57.1 48.6 46.2 36.3
100 94 79 78 22 16
22.8 21.4 18.0 17.8 5.0 3.6
63 66 60 56 17 10
29.7 31.1 28.3 26.4 8.0 4.7
134 26 19 15
30.5 5.9 4.3 3.4
19 14 12 13
9.0 8.5 5.7 6.1
13
2.9
7
3.3
7 6 3 2 1
1.6 1.4 0.7 0.5 0.2
5 3 1 2
2.4 1.4 0.5 0.9
Percentages were calculated from 439. Percentages were calculated from 212.
d
Variables in model
Beta
SE
P (Wald test)
Odds ratio
95% Confidence interval
Constant Gender (male versus female) Faculty Arts (versus medicine) Sports (versus medicine) Health insurance (none versus any) Alcohol use (drinker versus non-drinker) Monthly income (YTL)
1.493 0.370
0.423 0.221
<0.001 0.094
1.448
0.939–2.232
0.907
0.272
0.001
2.478
1.455–4.219
2.221
0.319
<0.001
9.214
4.934–17.206
0.777
0.329
0.018
2.174
1.143–4.149
0.913
0.241
<0.001
2.506
1.562–4.021
0.002
0.001
0.001
1.002
1.001–1.003
not habitual caffeine users, vulnerability to caffeine intoxication may be markedly increased due to an absence of pharmacologic tolerance. Genetic factors may also contribute to an individual’s vulnerability to caffeine-related disorders including caffeine intoxication, dependence, and withdrawal [2]. In our study group, most participants reported that they prefer energy drinks to feel ‘‘energetic,’’ to concentrate while studying, and/or to stay awake. Most of these effects of energy drinks are related to the caffeine content of such drinks. McCuker et al. [17] studied the caffeine content of energy drinks in comparison with young adults’ other popular drinks of carbonated sodas and found that the caffeine concentration of energy drinks ranged from 0 to 141.1 mg/serving, being quite higher than that of other carbonated sodas [17]. The greater the caffeine concentration, the more likely will the students experience such effects and that they will continue consuming such drinks. It is important to note that the stimulating properties of energy drinks can boost the heart beat and blood pressure, dehydrate the body, and prevent sleep. Given that individuals’ responses to caffeine vary, young individuals should be careful in consuming caffeine including drinks. Bender et al. [14] studied the hemodynamic effects of acute caffeine intake in young adults 21–26 y old and found a heart rate afterload up to 4.5 h after caffeine consumption. In a randomized, double-blind study, Waring et al. [5] found that acute caffeine intake significantly increases central blood pressure and large artery waveform transmission and decreased pressure amplification in healthy adults. This finding implied that the effects of caffeine on blood pressure may be significantly underestimated by the measurement of blood pressure at the brachial artery and caffeine-related circulatory health hazards could be underestimated in routine physical examination. It is noteworthy that in our study group more than 90% of ever users of energy drinks were not aware of the hazardous effects of energy drinks on the heart. Similarly, fewer than 2% of all participants (and ever users of energy drinks alike) mentioned obesity as an effect of energydrink consumption. In a study primarily aimed at investigating whether energy drinks are contributing to the obesity epidemic, Rush et al. [11] studied healthy women 18–22 y of age and found that energy-drink consumption apparently caused increased carbohydrate oxidation and reduced lipid oxidation, suggesting that the combined effects of caffeine and sucrose intake may cause obesity, especially in sedentary individuals. Of our participants, about one-tenth stated that they use energy drinks to mix with alcohol, to make alcoholic beverages taste better, or to decrease the depressive effects of alcohol. Such
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habits are common among college students in many other countries. A study of 500 students of the School of Medicine, University of Messina found that 56.9% of students were using energy drinks and, of those, 48.4% consumed energy drinks with alcohol, with more than one-third of alcohol and energy-drink consumers dong so more than three times in the previous month [6]. In a similar cross-sectional study aimed to characterize the pattern of energy-drink consumption in a sample of physical education students in Argentina; gender, marital status, attendance in gym classes, athletic swim practice, and study in the morning were found to be associated with consumption of energy drinks. Of those who consumed energy drinks, 87.6% mixed them with alcohol, and 25.9% of the students reported they consume more alcohol when it is mixed with energy drinks [8]. In 2006, a Web-based survey conducted in 4271 college students in North Carolina (United States) found that 24% of alcohol drinkers in the previous 30 d consumed alcohol with energy drinks. Students who were male, white, intramural athletes, fraternity or sorority members or pledges, and younger were significantly more likely to consume alcohol with energy drinks [9]. In multivariable analyses, consumption of alcohol mixed with energy drinks was significantly associated with increased heavy episodic drinking and twice as many episodes of weekly drunkenness. It is important to note that the most hazardous use of energy drinks in terms of the health of young adults seems to be use of energy drinks in mixtures with alcohol. The stimulant nature of energy drinks against the depressant characteristics of alcoholic beverages leads to dangerous health outcomes when they are mixed. The stimulant effects mask how intoxicated the young individuals get when they drink alcohol, they continue to drink until the point that the stimulant effect of energy drinks in the mixture consumed wears off, and the depressant effect of alcohol become apparent. It is common that the individual will start to vomit at this point (and could easily aspirate it); or even worse, the young individual may develop respiratory depression and may even die before being taken to a health care facility. An even more frequently observed scenario is that a young individual will still feel alert after drinking glasses of alcohol/energy-drink mixtures, cannot realize how much alcohol has been consumed, and drives under such an influence, with a high potential of danger for himself/herself, other passengers, and/or innocent drivers or even pedestrians. A recent double-blind, placebo-controlled study in female subjects found that mixing an energy drink with alcohol negatively influences performance on a global measurement of cognitive functioning [10]. The media anecdotally report that drinking energy drinks in combination with alcohol and exercise could cause sudden cardiac death. In a recently published case study, an otherwise healthy 28-y-old man who had a cardiac arrest after a day of motocross racing was reported to have consumed excessive amounts of a caffeinated energy drink throughout the day of the accident. The investigators postulated that a combination of excessive ingestion of caffeine- and taurine-containing energy drinks and strenuous physical activity can produce myocardial ischemia by inducing coronary vasospasm [18]. In a prospective study conducted to determine the cardiac effects of a commercially available, multicomponent energy drink in 15 healthy volunteers, heart rate increased 5–7 beats/min and systolic blood pressure increased 10 mmHg after energy-drink consumption [19]. Wiklund et al. [20] investigated changes in the electrocardiogram and heart rate after intake of an energy drink, taken in combination with alcohol and exercise, and found that individuals predisposed to arrhythmia by congenital or other rhythm
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disorders could have an increased risk for malignant cardiac arrhythmia in such conditions. Our study indicated that most college students, including current users of energy drinks, are not aware of the ingredients of the energy drinks and most often energy drinks are not distinguished from ‘‘sports drinks.’’ It is important to distinguish sports drinks from energy drinks. In the Joint Position Statement on Nutrition and Athletic performance published by the American College of Sports Medicine, American Dietetic Association, and Dietitians of Canada, it is stated that consumption of sports drinks containing carbohydrates and electrolytes during exercise will provide fuel for the muscles, help maintain blood glucose and the thirst mechanism, and decrease the risk of dehydration or hyponatremia [21]. They state that athletes will not need vitamin and mineral supplements if adequate energy to maintain body weight is consumed from a variety of foods. However, supplements will be required for athletes who restrict energy intake, use severe weight-loss practices, eliminate one or more food groups from their diet, or consume high-carbohydrate diets with low micronutrient density. It is noteworthy that the Joint Position Statement emphasizes that the nutritional ergogenic aids should be used with caution and only after careful evaluation of the product for safety, efficacy, potency, and whether or not it is a banned or illegal substance [21]. O’Dea suggested that some adolescents consume sports drinks and energy drinks for their perceived physiologic benefits and that they may not be aware of any potential risks [15]. This is exactly what our study indicated. It is interesting that only onefifth of never users in our study population stated that energy drinks are ‘‘unhealthy’’ and declared this as the main reason for not trying one. Young individuals may have physiologic proneness to health hazards, may have some undiagnosed pathologic conditions (such as heart problems), may underestimate their pathologic signs and symptoms with the false belief that ‘‘diseases are for the elderly,’’ and may not seek help in the early stages. Thus, it is important to make young individuals aware of the potential health hazards of energy drinks that they may face, emphasizing the reasons for why they should be careful about not mixing energy drinks with alcohol. Most college students who had ever drunk an energy drink mentioned that they first tried it with friends. It is also known from international studies that such drinks are frequently used in social gatherings. Thus, it would be effective to introduce healthy nutritional habits and drinks to young adults, besides replacing ‘‘unhealthy’’ socializing tools (cigarette smoking, alcohol or energy drink consumption, etc.) with healthier ones. Given that the consumption of energy drinks increases proportional to their availability to adolescents and youngsters, interventions should target decreasing the availability of soft drinks in the home and school environment and replacing them with more nutritive beverages [22]. Health-related classes in school curricula should include sections about healthy nutrition (including drinks and supplements); given that young adults try energy drinks at young ages, such educational activities should be provided before the high school years. It is noteworthy that none of the study participants mentioned that they had heard about the health hazards of energy drinks from parents/any family member, whereas a significant number first tried an energy drink at home, did so in presence of a family member, and/or currently consume energy drinks most often at home. These findings suggest that parents and family members should be taught and motivated to educate their young family members to consume energy drinks ‘‘wisely.’’
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Health educators should be aware that adolescents seek specific health benefits from such drinks and nutritional supplements, which may be better achieved through appropriate consumption of a nutritious diet. About half of all participants, more commonly among students of the CoS, consumed energy drinks to boost performance and/or to feel energetic. Health education programs should incorporate the perceptions, aspirations, and motivations of young people into the planning of interventions and activities to make them most relevant and effective [15]. Education on the health hazards of various nutritional elements and/or supplements can be inserted in school curricula. Such educational interventions will definitely benefit from educational, targeted, media messages, if prepared on a scientific basis. In the interim, further scientific research is needed to investigate the potential health hazards of energy drinks. Given the great variety of ingredients and/or amounts, it may be appropriate to differentiate individual brands with respect to their advantageous and hazardous ingredients for young individuals. Conclusions The use of energy drinks is quite common among college students but their knowledge of ingredients and potential health hazards of such drinks is very limited. Parents, teachers, health educators, and media professionals should take responsibility to educate the public (youngsters, in particular) about the health hazards of energy drinks and to increase motivation for a healthy diet. Acknowledgments The authors acknowledge Drs. Mahir Seyrek, Ozan Baris Nadaroglu, Mehmet Cal, and Ali Vefa Sayrac for their precious efforts in collection of field data and conduction of the preliminary statistical analyses during their internship. References [1] Popkin BM, Armstrong LE, Bray GM, Caballero B, Frei B, Willett WC. A new proposed guidance system for beverage consumption in the United States. Am J Clin Nutr 2006;83:529–42. [2] Reissig CJ, Strain EC, Griffiths RR. Caffeinated energy drinksda growing problem. Drug Alcohol Depend 2009;99:1–10. [3] Clauson KA, Shields KM, McQueen CE, Persad N. Safety issues associated with commercially available energy drinks. J Am Pharm Assoc 2008;48:e55–63.
[4] Astorino TA, Roberson DW. Efficacy of acute caffeine ingestion for short term high-intensity exercise performance: a systematic review. J Strenghth Cond Res 2010;24:257–65. [5] Waring WS, Goudsmit J, Marwick J, Webb DJ, Maxwell SR. Acute caffeine intake influences central more than peripheral blood pressure in young adults. Am J Hypertens 2003;16:919–24. [6] Oteri A, Salvo F, Caputi AP, Calapai G. Intake of energy drinks in association with alcoholic beverages in a cohort of students of the School of Medicine of the University of Messina. Alcohol Clin Exp Res 2007;31:1677–80. [7] Malinauskas BM, Aeby VG, Overton RF, Carpenter-Aeby T, Barber-Heidal K. A survey of energy drink consumption patterns among college students. Nutr J 2007;6:35. [8] Ballistreri MC, Corradi-Webster CM. Consumption of energy drinks among physical education students. Rev Lat Am Enfermagem 2008;16:558–64. [9] O’Brien MC, McCoy TP, Rhodes SD, Wagoner A, Wolfson M. Caffeinated cocktails: energy drink consumption, high-risk drinking, and alcoholrelated consequences among college students. Acad Emerg Med 2008;15:453–60. [10] Curry K, Stasio MJ. The effects of energy drinks alone and with alcohol on neuropsychological functioning. Hum Psycholparmacol 2009;24: 473–81. [11] Rush E, Schulz S, Obolonkin V, Simmons D, Plank L. Are energy drinks contributing to the obesity epidemic? Asia Pac J Clin Nutr 2006;15: 242–4. [12] Rothman KJ, Greenland S. Modern epidemiology. 2nd ed. Philadelphia: Lippincott-Raven; 1998. p. 78, 143–145. [13] Turkish Nutrition Codex. Declaration on energy drinks (Turkey), no. 2006/ 47 (in Turkish). Available at: http://www.kkgm.gov.tr/Mevzuat/khk560/ Kodeks/Tebligler/. Accessed January 12, 2010. [14] Bender AM, Donnerstein RL, Samson RA, Zhu D, Goldberg SJ. Hemodynamic effects of acute caffeine ingestion in young adults. Am J Cardiol 1997;79:696–9. [15] O’Dea JA. Consumption of nutritional supplements among adolescents: usage and perceived benefits. Health Educ Res 2003;18:98–107. [16] Iyadurai SJ, Chung SS. New-onset seizures in adults: possible association with consumption of popular energy drinks. Epilepsy Behav 2007;10: 504–8. [17] McCuker RR, Goldberger BA, Cone EJ. Caffeine content of energy drinks, carbonated sodas, and other beverages. J Anal Toxicol 2006;30:112–4. [18] Berger AJ, Alford K. Cardiac arrest in a young man following excess consumption of caffeinated ‘‘energy drinks. Med J Aust 2009;190:41–3. [19] Steinke L, Lanfear DE, Dhanapal V, Kalus JS. Effect of ‘‘energy drink’’ consumption on hemodynamic and electrocardiographic parameters in healthy young adults. Ann Pharmacother 2009;43:596–602. [20] Wiklund U, Karlsson M, Ostro¨m M, Messner T. Influence of energy drinks and alcohol on post-exercise heart rate recovery and heart rate variability. Clin Physiol Funct Imaging 2009;29:74–80. [21] American College of Sports Medicine, American Dietetic Association, Dietitians of Canada. Joint position statement: nutrition and athletic performance. American College of Sports Medicine, American Dietetic Association, Dietitians of Canada. Med Sci Sports Exerc 2000;32:2130–45. [22] Denney-Wilson E, Crawford D, Dobbins T, Hardy L, Okely AD. Influences on consumption of soft drinks and fast foods in adolescents. Asia Pac J Clin Nutr 2009;18:447–52.
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Applied nutritional investigation
Energy-drink consumption in college students and associated factors Sema Attila Ph.D. *, Banu Çakir M.D., M.P.H., Ph.D. Department of Public Health, Hacettepe University Faculty of Medicine, Ankara, Turkey
a r t i c l e i n f o
a b s t r a c t
Article history: Received 26 October 2009 Accepted 11 February 2010
Objective: To investigate the frequency of energy-drink consumption and associated factors in a group of college students. Methods: A cross-sectional study was conducted in Hacettepe University (Ankara, Turkey) and included 439 students pursuing a career in medicine, sports, and arts. Only fourth-year students were approached. Data were collected using a self-administered standard questionnaire. Results: In bivariate analyses, frequency of energy-drink consumption was higher in students of arts and sports and in those who did not have breakfast on a regular basis, ever smoked cigarettes, drank alcoholic beverages, and regularly engaged in sports compared with their counterparts. Many students who had ‘‘ever’’ tried an energy drink did so the first time because they wondered about its taste. Of regular users of energy drinks, reasons for using such drinks varied across the three selected groups of students and included obtaining getting energy, staying awake, boosting performance while doing sports, or mixing with alcoholic beverages. About 40% of all current users of energy drinks reported that they mixed those with alcoholic beverages. In multivariate analyses, statistically significant predictors of energy-drink consumption were faculty type, presence of any health insurance, use of alcoholic beverages, and monthly income, controlling for gender. Most students could not correctly define the ingredients of energy drinks or their potential hazardous health effects, and they could not distinguish energy and sports drinks when they were requested to select them from a list of commercial names of various drinks. Conclusion: Consumption of energy drinks, despite the variation in the reason for choosing such drinks, is quite common in college students. Awareness of university students of the ingredients and potential health hazards of energy drinks, in particular in mixing with alcoholic beverages, should be increased. Ó 2011 Published by Elsevier Inc.
Keywords: Energy drinks Young adults College students
Introduction Fluids are a vital requirement for humans, but fluid intake can be obtained from a variety of fluid sources other than water. The selection of appropriate fluids, timing of the intake, and supplement choices are important for optimal health, especially in young people. The Beverage Guidance Panel, initiated by Popkin et al. [1] aims to provide guidance on the relative health and nutritional benefits and risks of various beverage categories. Popkin et al. [1] reported that in the United States daily calorie intake has recently increased about 150–300 kcal, with approximately 50% of the increase coming from the consumption of sweetened beverages. Although still a relatively small proportion in total fluid intake, the absolute rate of energy-drink use has been * Corresponding author. Tel.: þ90-312-305-1590; fax: þ90-312-311-0072. E-mail address: [email protected] (S. Attila). 0899-9007/$ - see front matter Ó 2011 Published by Elsevier Inc. doi:10.1016/j.nut.2010.02.008
increasing significantly, especially in young individuals. Energy drinks are beverages (e.g., Red Bull, Venom, Burn, and Adrenaline Rush) that contain large doses of caffeine and other legal stimulants such as taurine, carbohydrates, glucuronolactone, inositol, niacin, panthenol, and b-complex vitamins. Hundreds of different brands on the market have high caffeine content, ranging from a modest 50 mg to an alarming 505 mg per can or bottle [2]. Energy drinks have been found to improve attention and/or reaction times and indices of alertness in some studies; the combination of caffeine and glucose can ameliorate deficits in cognitive performance and subjective fatigue during extended periods of cognitive demand. However, several ingredients of energy drinks, with sucrose and caffeine taking the lead, may have unwanted health consequences in youngsters and should be used carefully. Energy drinks have stimulating properties that can boost heart rate and blood pressure, dehydrate the body, may aggravate the effects of other stimulants, and prevent sleep.
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Unlike sports drinks (the use of which is supported for athletes), energy drinks should not be used while exercising because the combination of fluid loss, sweating, and the diuretic quality of the caffeine can leave the user severely dehydrated [2–5]. Such drinks are widely consumed by young people, by college students, in particular, for a variety of reasons. Even more important from a public health point of view, international studies have indicated that mixing energy drinks with alcohol is fairly frequent among college students [6–8]. Mixing energy drinks with alcohol may be dangerous given the stimulant nature of energy drinks and depressant characteristics of the alcohol. The stimulant effect can mask how intoxicated a person is and prevent individuals from realizing how much they drink. The stimulated person seems alert and even companions cannot recognize ‘‘whether the person had enough alcohol’’: the blood alcohol concentration would be the same as in others; and as the stimulant effect wears off, the depressant effects of alcohol will become prominent, a person may vomit and even have respiratory depression. Moreover, alcohol and energy drinks are very dehydrating and together will hinder the body’s ability to metabolize alcohol and further increase the toxicity of alcohol [2,3,9,10]. Although energy drinks are mainly targeted to young adult consumers, there has been little research regarding effects of energy-drink consumption by college students and the potential for related health hazards [6,7,9,11]. Observations have suggested that young adults can easily access energy drinks and use energy drinks frequently, but there is scarce evidence on the reasons why they consume energy drinks and whether they are aware of the potential health hazards. This study examined the frequency of consumption of energy drinks in a group of university students selected from different faculties, who were hypothesized to have different consumption habits, and investigated the factors for preferring such drinks. The study also examined students’ level of knowledge on ingredients and on potential health hazards of energy drinks. Last but not least, we reviewed related international work to compare and contrast local findings to encourage further discussion on the importance of energy-drink consumption in college students from a public health perspective and to brainstorm for potential interventions for the future. Materials and methods A cross-sectional study was conducted in students attending three colleges of Hacettepe University (Ankara, Turkey). It is important to note that the study aimed primarily to calculate consumption rates in various faculties, being mainly descriptive in nature, with no specific a priori hypotheses, but with an ultimate objective of screening/generating some hypotheses on potential risk factors of energy-drink consumption and related patterns (if any) [12]. School selection was based on the likelihood of energy-drink use by students. Students from the Faculty of Medicine (FoM), College of Sports (CoS), and College of Arts (CoA) were approached because these students were likely to use energy drinks to stay awake for studying or during night calls in the hospital; to boost their performance in exercising; and to be exposed more to energy drinks in social gatherings, activities, plays, etc., respectively. To eliminate the potential confounding effect of age, the study group was restricted in the planning stage to final year (fourth year) students of the CoS and CoA and fourth-year students of the FoM [12]. All students attending classes on the day of data collection were approached and included in the study if they agreed to participate. The study included 439 students, with 254 (57.9%), 94 (21.4%), and 91 (20.7%) students from the FoM, CoA, and CoS, respectively. More than 95% of all students approached took part in the study; however, completion rates of the total number of registered students of the selected schools stayed below 80%, given low attendance rates to classes, being out of school due to practical training in the field, etc. Data were collected via a self-administered, standard, pretested questionnaire. The questionnaire consisted of 35 questions on students’ sociodemographic characteristics, personal habits, total fluid intake, energy-drink–related knowledge, and habits.
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Written approval was obtained from each faculty’s administrators before research, and verbal (informed) consent was received from each participant. Participation was totally voluntary and no incentives were provided to participants. In the study, students were first asked whether they had ever used any energy drinks. Later, they were given a list of beverages available in the market, including energy drinks, sports drinks, and soft drinks. They were requested to mark which of those they tried at least once. Once they answered this question, a standard definition was provided to them to explain what was meant by an ‘‘energy drink.’’ In the study, energy drinks were defined as ‘‘drinks that provide energy due to carbohydrates in composition and include legal vitamin and minerals in specified amounts,’’ as defined by the Turkish Nutrition Codex [13]. Later, they were asked again whether they had ever used such a drink. Distributions of ‘‘energy-drink use’’ and discussed throughout this report are based on this second question, according to a standard definition and thus were considered to be more robust. Of note, our comparison of the number of reportedly ‘‘ever users of energy drinks’’ matched quite well with the number of students who checked at least one of the energy/sports drinks in the provided list of beverages.
Statistical analysis Statistical analyses included frequency and percentages of distributions. The status of knowledge on ingredients and potential health hazards of energy drinks was comparatively studied for ‘‘ever’’ users of energy drinks versus among all study participants. An exploratory analysis was performed to model significant predictors of energy-drink consumption (ever users versus never users). Gender, age (22 and >22 y, i.e., the median age), family type (nuclear versus other), place of residency (with family/siblings versus other), possession of health insurance (any versus none), monthly income, educational attainment of the mother (higher than secondary school versus below), educational attainment of the father (higher than secondary school versus below), sleeping habits (regular versus irregular), cigarette smoking (ever versus never), alcohol use (ever versus never), presence of at least one ‘‘risk-taking behavior’’ having breakfast (regular versus irregular/none), and doing sports (regular versus irregular/none; the latter two were used as surrogate measurements for ‘‘healthy behavior’’) were checked for their potential associations with energy consumption because these were the factors identified in previous studies as being associated with energy-drink consumption and/or as potential confounders. A backward elimination logistic regression modeling technique was used to reach the most parsimonious yet statistically significant model. Gender was added to the final model to make the final model comparable to those obtained from other studies that were/could be conducted elsewhere.
Results The study included 439 college students, with ages from 19 to 39 y, with a mean standard deviation of 22.8 2.09 y (median 22 y). Distribution of age was quite homogenous in the FoM group, but varied widely in the CoA group. Table 1 presents the distribution of sociodemographic characteristics of study participants. Of the group, more than half were students in the FoM (n ¼ 254), 94 students were from the CoA, and 91 students were from the CoS. The study aimed to include fourth-year students in all three schools; however, in the CoA and CoS, some students (<5%) from lower classes were included in the study because they took the selected class on the day data were collected. Of the study participants, 91.3% were from nuclear families of a middle-to-high cultural level (80.2% of fathers and 62.6% of mothers had at least a high school level education; 38.0% of fathers and 22.8% of mothers had science-related occupations). About half of students used to live with their parents, and only 9.1% were living alone. Of the students, 13.4% reported that they had no health insurance and the rest had some sort of health insurance. Students were asked to report the average monthly income that ‘‘they spend for their personal needs’’ (excluding rent, school fees, etc.): the average monthly income of the group corresponded to the minimum legal income of a worker in Turkey, which was quite adequate for a student.
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The study collected data on personal habits of the study participants that could be associated with energy-drink use. Table 2 presents the distribution of some personal habits of study participants. Based on students’ self-reports, 45.1% used to have regular sleep patterns, with an average period of 7.23 1.31 h/d. Of all students studied, 64.0% had never tried smoking, whereas 26.9% were current smokers: average pack-years of cigarette smoking were 2.25 1.74 in ever-smokers and 3.94 2.86 in current smokers. Thirty-six percent of students (n ¼ 159) had never tried alcohol, and of the drinkers, more than 75% reported that they drink alcohol less than once a month. Students were asked to report whether they engaged in any of the following six behaviors and the frequency of risk takers were calculated for these risk-taking behaviors: ‘‘not using a seat belt’’ (37.8%), ‘‘driving fast’’ (26.2%), ‘‘driving under the influence of alcohol’’ (6.4%), ‘‘unsafe sex’’ (13.9%), ‘‘carrying guns/weaponry’’ (6.4%), and ‘‘applying violence against friends’’ (7.1%). In the group, 63.6% reported that they did sports regularly; because one-fourth of the study participants were from the CoS, this question did not provide much information. Half the students reported that they regularly have breakfast on a daily basis and more than half of the students used to regularly have at least three meals a day. Only 10% of students reported having a chronic
Table 1 Distribution of sociodemographic characteristics of study participants (n ¼ 439) Characteristics Gender Male Female Age groups (y) 20 21–24 25 Family type Nuclear Extended Other Shares residency with Parents and/or siblings Friends Lives in dormitory Lives alone Social insurance Governments Employee Retirement Fund Social Security Association Bag-Kur Private insurance Green Card None Monthly income used for personal requirements (YTL) <250 250–499 500–999 1000 Educational attainment of mother Literate/illiterate (no schooling) Primary school graduate Middle school graduate High school graduate College/university graduate (including postgraduate degrees) Educational attainment of father Literate/illiterate (no schooling) Primary school graduate Middle school graduate High school graduate College/university graduate (including postgraduate degrees)
No.
Percentage
222 217
50.6 49.4
28 315 60
6.4 79.9 13.7
401 31 7
91.3 7.1 1.6
215 123 61 40
49.0 28.0 13.9 9.1
219 102 42 16 1 59
49.9 23.2 9.6 3.6 0.2 13.5
104 195 124 16
23.7 44.4 28.3 3.6
10 56 21 107 245
2.2 12.8 4.8 24.4 55.8
21 116 27 131 144
4.8 26.4 6.2 29.8 32.8
Table 2 Distribution of some personal habits of study participants Characteristics Sleeping habits Regular Irregular Daily sleeping hours (on average) 6 7 8 9 Cigarette smoking Never smoked Quitters Current smokers Alcohol use Never Ever Risk-taking behaviors* Not use safety belts Drive cars fast Drive under influence of alcohol Unsafe sex Carry guns/weaponry Violence to/from friends Doing sports Regular Irregular/none Having breakfast Regularly Irregularly Never
No.
Percentage
198 241
45.1 54.9
116 138 137 48
26.5 31.5 31.2 10.8
281 40 118
64.0 9.1 26.9
159 280
36.2 63.8
166 115 28 61 28 31
37.8 26.2 6.4 13.9 6.4 7.1
160 279
36.4 63.6
229 176 34
52.2 40.1 7.7
* Percentages were calculated from 439. Given that more than one risk-taking behavior can be present, totals do not sum to 100.0.
disease and the most commonly reported three conditions were depression, migraine, and asthma. The study also investigated whether energy-drink use in young adults is associated with general health status, habits, and/or risk-taking/healthy lifestyle behaviors; Table 3 presents related findings of energy-drink use and related behaviors in study participants. The most commonly preferred drink was water and almost half of study participants reported that they drink at least five glasses of water per day. Of the students, 48.3% (n ¼ 212) had ever tried an energy drink (Table 3). The most common reason to try an energy drink was ‘‘curiosity of its taste/effects’’ (48.3%), followed in order of frequency by ‘‘for energy’’ and ‘‘to boost performance.’’ About one-third of students who had never tried an energy drink reported no specific reason for that, 36.1% reported that they did not wonder about its taste, whereas 19.4% had not tried an energy drink before because they considered such drinks ‘‘unhealthy.’’ Sixty percent first used these drinks during their college years, with the most common places for a first try being ‘‘home’’, ‘‘recreational areas,’’ and ‘‘bars.’’ Most often, the students had tried their first energy drink in the company of a ‘‘friend.’’ Of current users of energy drinks (n ¼ 145), most did so to ‘‘get energy’’ or ‘‘to boost their performance in doing sports’’ and only 9.7% used energy drinks with meals. About half of ‘‘current’’ energy drinkers used such drinks in recreational areas while doing sports and about one-third did so in bars (Table 4). The distribution of answers to questions inquiring about students’ knowledge of the ingredients and potential health hazards of energy drinks is presented in Table 5. Only one-third of all participants and a little more than half of ‘‘ever’’ drinkers of energy drinks reported that they ‘‘knew’’ the ingredients of energy drinks. However, the most commonly reported
S. Attila, B. Çakir / Nutrition 27 (2011) 316–322 Table 3 Energy-drink use and related behaviors among study participants Characteristics Use of energy drinks Ever Never Main reason for NOT trying energy drinks (n ¼ 227) No particular reason No ‘‘curiosity’’ to try Think them as ‘‘unhealthy’’ Not aware of ingredients High calories Not need energy Expensive Think them as ‘‘addictive’’ Main reason for using energy drinks (n ¼ 201) Wondered its taste To feel ‘‘energetic’’ To boost performance during exercise To mix with alcohol To stay awake for long hours To boost performance while reading/studying Timing of first experience with energy drinks (n ¼ 197) In secondary school In high school In college/university Place where first tried an energy drink (n ¼ 201) At home Doing sports (in recreational areas) Bar In the street Coffee shop In dormitory Other places Not remember Any companion when first tried an energy drink (n ¼ 201) None Friend(s) Family members Boy/girlfriend
No.
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Table 4 Energy-drink use behaviors among ‘‘current’’ users of energy drinks (n ¼ 145) Percentage
212 227
48.3 51.7
84 82 44 6 4 4 2 1
37.0 36.1 19.4 2.6 1.8 1.8 0.9 0.4
98 32 30 24 10 8
48.3 15.9 14.9 11.9 5.0 4.0
9 76 122
4.3 36.8 58.9
49 48 29 24 21 8 8 14
24.4 23.9 14.4 11.9 10.4 4.0 4.0 7.0
59 119 12 11
29.4 59.2 6.0 5.4
ingredients are sugar and caffeine, and most students did not correctly mark the other ingredients given in multiple choices (Table 5). It is important to note that 37.2% of students reported that they mixed energy drinks with alcohol, whereas 62.8% of ‘‘ever’’ users had never done so. As presented in Table 5, almost half the students who reported that they knew the health effects of energy drinks and reported the source of their knowledge learned about the effects of energy drinks in classes and/or educational materials provided in schools. Media messages were reported as the major source of information on energy drinks by one-third of the students. One of every five students reported that they learned about energy drinks from their friends/peers. In binary analyses, ‘‘ever’’ use of energy drinks (versus never users) was found to be statistically significantly associated with the type of school, health insurance, smoking, alcohol use, and doing sports. Binary analyses also suggested that students with a higher monthly income were more likely to use energy drinks than their counterparts with a lower income (Table 6). Table 7 presents the final logistic regression model for energy-drink consumption by study participants (ever users versus never users). Logistic regression modeling of energydrink use (ever drinking versus never drinking) indicated that, controlling for age, men were 1.5 times more likely than women
Characteristics Frequency of energy-drink use >2 bottles/d 2 bottles/d 1 bottle/d <1 bottle/d Type of energy drink preferred* Red Bull Powerade Burn Other (Gatorade, Red Devil, Shark) Unspecified Reasons for using energy drinks* To feel ‘‘energetic’’ To boost performance during exercise For its taste Use in cocktails, mixed with alcohol To concentrate while studying To stay awake No specific reason Relation to regular meals Drink with meals Not drink with meals With or without meals Place where energy drink is consumed* Recreational areas Bars At home Coffee shop In dormitory In campus *
No.
Percentage
2 5 8 130
1.4 3.4 5.5 89.7
75 30 29 4 7
51.7 20.7 20.0 2.8 4.8
35 31 26 22 13 11 7
24.2 21.4 17.0 15.2 8.9 7.6 4.8
131 10 4
90.3 6.9 2.8
68 47 45 32 30 19
46.9 32.4 31.0 22.1 20.7 13.1
Percentages were calculated from 145.
to use energy drinks; alcohol drinkers were 2.5 times more likely to use energy drinks than alcohol non-users; and students of the CoA (2.5 times) and CoS (9.2 times) were more likely than medical students to ever taste energy drinks. Having no health insurance (a surrogate measurement for low socioeconomic status) was also positively and significantly associated with energy-drink use. Students with reportedly higher monthly incomes were more likely to try energy drinks than their counterparts with lower incomes.
Discussion The energy-drink market has grown exponentially over the past decade. The absence of regulatory oversight in many countries has resulted in aggressive marketing of energy drinks over the world, targeted primarily toward young adults (men in particular). Using energy drinks is a popular practice among college students for a variety of situations: to compensate for insufficient sleep, to increase energy, while studying, while driving for long periods, drinking with alcohol while partying, and to treat a hangover. Some previous work suggested that young people may use energy drinks as ‘‘natural alternatives’’ to other fluids, ‘‘to boost performance and concentration,’’ ‘‘to stay awake before exams,’’ ‘‘to mix with alcoholic beverages to improve the taste,’’ etc. [2,8,14,15]. Almost all these reasons were mentioned as the underlying factor for ‘‘trying/using energy drinks’’ in our study population. In addition to the frequency of an agent, the associated burdens of morbidity and mortality determine its significance as a public health concern. Although energy drinks are targeted to young adult consumers, there has been little research regarding
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Table 5 Energy-drink–related knowledge by study participants Characteristics Having knowledge on ingredients of energy drinks, based on self-reports Among all study participants (n ¼ 439) Among those who have ‘‘ever’’ used an energy drink (n ¼ 212) Source of knowledge on health hazards of energy drinks (n ¼ 128) Classes in school Visual media Friends Written media Other (not specified)
Table 7 Logistic regression model for ‘‘ever’’ use of energy drinks
No.
Percentage
128 116
29.2 54.7
44 21 18 11 34
34.4 16.4 14.1 8.6 26.5
the health effects of energy-drink consumption by college students. Clauson et al. [3] recently published a review article on the benefits and adverse effects associated with the consumption of energy drinks. Based on data from searches for published articles written on energy drinks, the investigators concluded that most energy drinks contain natural products and that amounts of guarana, taurine, and ginseng found in popular energy drinks are far below the amounts expected to deliver therapeutic benefits or adverse events. However, caffeine and sugar are present in amounts known to cause a variety of adverse health effects. Caffeine in the quantities present in most energy drinks may lead to insomnia, nervousness, headache, tachycardia, and seizures [3,16]. In children and adolescents who are Table 6 Knowledge of study participants about ingredients and health hazards of energy drinks Characteristics
Ingredients of energy drinks, as chosen by study participants from given choices Sugar Caffeine Salt and minerals Vitamins Carbon dioxide and other gases Doping agents Citric acid Taurine Protein Alcohol Nicotine Effects of energy drinks as reported by study participants Hazardous for heart Decreases sleeping hours Provides energy Supplies water and minerals No beneficial effect on health Addictive Causes obesity Causes depression Causes insulin resistance Causes peptic ulcer * y
All participants (n ¼ 439)
‘‘Ever’’ users of energy drinks (n ¼ 212)
No.
Percentage*
No.
Percentagey
214 171 139 130 105
48.7 39.0 31.7 29.6 23.9
149 121 103 98 77
70.3 57.1 48.6 46.2 36.3
100 94 79 78 22 16
22.8 21.4 18.0 17.8 5.0 3.6
63 66 60 56 17 10
29.7 31.1 28.3 26.4 8.0 4.7
134 26 19 15
30.5 5.9 4.3 3.4
19 14 12 13
9.0 8.5 5.7 6.1
13
2.9
7
3.3
7 6 3 2 1
1.6 1.4 0.7 0.5 0.2
5 3 1 2
2.4 1.4 0.5 0.9
Percentages were calculated from 439. Percentages were calculated from 212.
d
Variables in model
Beta
SE
P (Wald test)
Odds ratio
95% Confidence interval
Constant Gender (male versus female) Faculty Arts (versus medicine) Sports (versus medicine) Health insurance (none versus any) Alcohol use (drinker versus non-drinker) Monthly income (YTL)
1.493 0.370
0.423 0.221
<0.001 0.094
1.448
0.939–2.232
0.907
0.272
0.001
2.478
1.455–4.219
2.221
0.319
<0.001
9.214
4.934–17.206
0.777
0.329
0.018
2.174
1.143–4.149
0.913
0.241
<0.001
2.506
1.562–4.021
0.002
0.001
0.001
1.002
1.001–1.003
not habitual caffeine users, vulnerability to caffeine intoxication may be markedly increased due to an absence of pharmacologic tolerance. Genetic factors may also contribute to an individual’s vulnerability to caffeine-related disorders including caffeine intoxication, dependence, and withdrawal [2]. In our study group, most participants reported that they prefer energy drinks to feel ‘‘energetic,’’ to concentrate while studying, and/or to stay awake. Most of these effects of energy drinks are related to the caffeine content of such drinks. McCuker et al. [17] studied the caffeine content of energy drinks in comparison with young adults’ other popular drinks of carbonated sodas and found that the caffeine concentration of energy drinks ranged from 0 to 141.1 mg/serving, being quite higher than that of other carbonated sodas [17]. The greater the caffeine concentration, the more likely will the students experience such effects and that they will continue consuming such drinks. It is important to note that the stimulating properties of energy drinks can boost the heart beat and blood pressure, dehydrate the body, and prevent sleep. Given that individuals’ responses to caffeine vary, young individuals should be careful in consuming caffeine including drinks. Bender et al. [14] studied the hemodynamic effects of acute caffeine intake in young adults 21–26 y old and found a heart rate afterload up to 4.5 h after caffeine consumption. In a randomized, double-blind study, Waring et al. [5] found that acute caffeine intake significantly increases central blood pressure and large artery waveform transmission and decreased pressure amplification in healthy adults. This finding implied that the effects of caffeine on blood pressure may be significantly underestimated by the measurement of blood pressure at the brachial artery and caffeine-related circulatory health hazards could be underestimated in routine physical examination. It is noteworthy that in our study group more than 90% of ever users of energy drinks were not aware of the hazardous effects of energy drinks on the heart. Similarly, fewer than 2% of all participants (and ever users of energy drinks alike) mentioned obesity as an effect of energydrink consumption. In a study primarily aimed at investigating whether energy drinks are contributing to the obesity epidemic, Rush et al. [11] studied healthy women 18–22 y of age and found that energy-drink consumption apparently caused increased carbohydrate oxidation and reduced lipid oxidation, suggesting that the combined effects of caffeine and sucrose intake may cause obesity, especially in sedentary individuals. Of our participants, about one-tenth stated that they use energy drinks to mix with alcohol, to make alcoholic beverages taste better, or to decrease the depressive effects of alcohol. Such
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habits are common among college students in many other countries. A study of 500 students of the School of Medicine, University of Messina found that 56.9% of students were using energy drinks and, of those, 48.4% consumed energy drinks with alcohol, with more than one-third of alcohol and energy-drink consumers dong so more than three times in the previous month [6]. In a similar cross-sectional study aimed to characterize the pattern of energy-drink consumption in a sample of physical education students in Argentina; gender, marital status, attendance in gym classes, athletic swim practice, and study in the morning were found to be associated with consumption of energy drinks. Of those who consumed energy drinks, 87.6% mixed them with alcohol, and 25.9% of the students reported they consume more alcohol when it is mixed with energy drinks [8]. In 2006, a Web-based survey conducted in 4271 college students in North Carolina (United States) found that 24% of alcohol drinkers in the previous 30 d consumed alcohol with energy drinks. Students who were male, white, intramural athletes, fraternity or sorority members or pledges, and younger were significantly more likely to consume alcohol with energy drinks [9]. In multivariable analyses, consumption of alcohol mixed with energy drinks was significantly associated with increased heavy episodic drinking and twice as many episodes of weekly drunkenness. It is important to note that the most hazardous use of energy drinks in terms of the health of young adults seems to be use of energy drinks in mixtures with alcohol. The stimulant nature of energy drinks against the depressant characteristics of alcoholic beverages leads to dangerous health outcomes when they are mixed. The stimulant effects mask how intoxicated the young individuals get when they drink alcohol, they continue to drink until the point that the stimulant effect of energy drinks in the mixture consumed wears off, and the depressant effect of alcohol become apparent. It is common that the individual will start to vomit at this point (and could easily aspirate it); or even worse, the young individual may develop respiratory depression and may even die before being taken to a health care facility. An even more frequently observed scenario is that a young individual will still feel alert after drinking glasses of alcohol/energy-drink mixtures, cannot realize how much alcohol has been consumed, and drives under such an influence, with a high potential of danger for himself/herself, other passengers, and/or innocent drivers or even pedestrians. A recent double-blind, placebo-controlled study in female subjects found that mixing an energy drink with alcohol negatively influences performance on a global measurement of cognitive functioning [10]. The media anecdotally report that drinking energy drinks in combination with alcohol and exercise could cause sudden cardiac death. In a recently published case study, an otherwise healthy 28-y-old man who had a cardiac arrest after a day of motocross racing was reported to have consumed excessive amounts of a caffeinated energy drink throughout the day of the accident. The investigators postulated that a combination of excessive ingestion of caffeine- and taurine-containing energy drinks and strenuous physical activity can produce myocardial ischemia by inducing coronary vasospasm [18]. In a prospective study conducted to determine the cardiac effects of a commercially available, multicomponent energy drink in 15 healthy volunteers, heart rate increased 5–7 beats/min and systolic blood pressure increased 10 mmHg after energy-drink consumption [19]. Wiklund et al. [20] investigated changes in the electrocardiogram and heart rate after intake of an energy drink, taken in combination with alcohol and exercise, and found that individuals predisposed to arrhythmia by congenital or other rhythm
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disorders could have an increased risk for malignant cardiac arrhythmia in such conditions. Our study indicated that most college students, including current users of energy drinks, are not aware of the ingredients of the energy drinks and most often energy drinks are not distinguished from ‘‘sports drinks.’’ It is important to distinguish sports drinks from energy drinks. In the Joint Position Statement on Nutrition and Athletic performance published by the American College of Sports Medicine, American Dietetic Association, and Dietitians of Canada, it is stated that consumption of sports drinks containing carbohydrates and electrolytes during exercise will provide fuel for the muscles, help maintain blood glucose and the thirst mechanism, and decrease the risk of dehydration or hyponatremia [21]. They state that athletes will not need vitamin and mineral supplements if adequate energy to maintain body weight is consumed from a variety of foods. However, supplements will be required for athletes who restrict energy intake, use severe weight-loss practices, eliminate one or more food groups from their diet, or consume high-carbohydrate diets with low micronutrient density. It is noteworthy that the Joint Position Statement emphasizes that the nutritional ergogenic aids should be used with caution and only after careful evaluation of the product for safety, efficacy, potency, and whether or not it is a banned or illegal substance [21]. O’Dea suggested that some adolescents consume sports drinks and energy drinks for their perceived physiologic benefits and that they may not be aware of any potential risks [15]. This is exactly what our study indicated. It is interesting that only onefifth of never users in our study population stated that energy drinks are ‘‘unhealthy’’ and declared this as the main reason for not trying one. Young individuals may have physiologic proneness to health hazards, may have some undiagnosed pathologic conditions (such as heart problems), may underestimate their pathologic signs and symptoms with the false belief that ‘‘diseases are for the elderly,’’ and may not seek help in the early stages. Thus, it is important to make young individuals aware of the potential health hazards of energy drinks that they may face, emphasizing the reasons for why they should be careful about not mixing energy drinks with alcohol. Most college students who had ever drunk an energy drink mentioned that they first tried it with friends. It is also known from international studies that such drinks are frequently used in social gatherings. Thus, it would be effective to introduce healthy nutritional habits and drinks to young adults, besides replacing ‘‘unhealthy’’ socializing tools (cigarette smoking, alcohol or energy drink consumption, etc.) with healthier ones. Given that the consumption of energy drinks increases proportional to their availability to adolescents and youngsters, interventions should target decreasing the availability of soft drinks in the home and school environment and replacing them with more nutritive beverages [22]. Health-related classes in school curricula should include sections about healthy nutrition (including drinks and supplements); given that young adults try energy drinks at young ages, such educational activities should be provided before the high school years. It is noteworthy that none of the study participants mentioned that they had heard about the health hazards of energy drinks from parents/any family member, whereas a significant number first tried an energy drink at home, did so in presence of a family member, and/or currently consume energy drinks most often at home. These findings suggest that parents and family members should be taught and motivated to educate their young family members to consume energy drinks ‘‘wisely.’’
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Health educators should be aware that adolescents seek specific health benefits from such drinks and nutritional supplements, which may be better achieved through appropriate consumption of a nutritious diet. About half of all participants, more commonly among students of the CoS, consumed energy drinks to boost performance and/or to feel energetic. Health education programs should incorporate the perceptions, aspirations, and motivations of young people into the planning of interventions and activities to make them most relevant and effective [15]. Education on the health hazards of various nutritional elements and/or supplements can be inserted in school curricula. Such educational interventions will definitely benefit from educational, targeted, media messages, if prepared on a scientific basis. In the interim, further scientific research is needed to investigate the potential health hazards of energy drinks. Given the great variety of ingredients and/or amounts, it may be appropriate to differentiate individual brands with respect to their advantageous and hazardous ingredients for young individuals. Conclusions The use of energy drinks is quite common among college students but their knowledge of ingredients and potential health hazards of such drinks is very limited. Parents, teachers, health educators, and media professionals should take responsibility to educate the public (youngsters, in particular) about the health hazards of energy drinks and to increase motivation for a healthy diet. Acknowledgments The authors acknowledge Drs. Mahir Seyrek, Ozan Baris Nadaroglu, Mehmet Cal, and Ali Vefa Sayrac for their precious efforts in collection of field data and conduction of the preliminary statistical analyses during their internship. References [1] Popkin BM, Armstrong LE, Bray GM, Caballero B, Frei B, Willett WC. A new proposed guidance system for beverage consumption in the United States. Am J Clin Nutr 2006;83:529–42. [2] Reissig CJ, Strain EC, Griffiths RR. Caffeinated energy drinksda growing problem. Drug Alcohol Depend 2009;99:1–10. [3] Clauson KA, Shields KM, McQueen CE, Persad N. Safety issues associated with commercially available energy drinks. J Am Pharm Assoc 2008;48:e55–63.
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