Adolescent energy drink consumption: An Australian perspective

Appetite 105 (2016) 638e642

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Adolescent energy drink consumption: An Australian perspective Beth M. Costa*, Alexa Hayley, Peter Miller School of Psychology, Deakin University, Australia

a r t i c l e i n f o

a b s t r a c t

Article history: Received 21 September 2015 Received in revised form 29 June 2016 Accepted 1 July 2016 Available online 4 July 2016

Caffeinated Energy Drinks (EDs) are not recommended for consumption by children, yet there is a lack of age-specific recommendations and restrictions on the marketing and sale of EDs. EDs are increasingly popular among adolescents despite growing evidence of their negative health effects. In the current study we examined ED consumption patterns among 399 Australian adolescents aged 12e18 years. Participants completed a self-report survey of consumption patterns, physiological symptoms, and awareness of current ED consumption guidelines. Results indicated that ED consumption was common among the sample; 56% reported lifetime ED consumption, with initial consumption at mean age 10 (SD ¼ 2.97). Twenty-eight percent of the sample consumed EDs at least monthly, 36% had exceeded the recommended two standard EDs/day, and 56% of consumers had experienced negative physiological health effects following ED consumption. The maximum number of EDs/day considered appropriate for children, adolescents, and adults varied, indicating a lack of awareness of current consumption recommendations. These findings add to the growing body of international evidence of adolescent ED consumption, and the detrimental impact of EDs to adolescent health. Enforced regulation and restriction of EDs for children’s and adolescents’ consumption is urgently needed in addition to greater visibility of ED consumption recommendations. © 2016 Elsevier Ltd. All rights reserved.

Keywords: Energy drinks Caffeine Adolescents Quantitative research

1. Introduction Energy drinks (EDs) such as Red Bull© contain caffeine and sugar and, in this respect, are similar to caffeinated soft drinks. EDs contain other implied active ingredients such as guarana, taurine, glucuronolactine, and B group vitamins, and hence are a unique beverage type (Pennay & Lubman, 2011). Within Australia, EDs are not recommended for consumption by children. Yet, as in other parts of the world, Australia lacks age-specific consumption recommendations and restrictions on the marketing and sale of EDs. Consequently aggressive marketing targeted to youth associates ED consumption with high risk behaviours such as extreme sports involving risk of physical injury (e.g., motor racing) (Breda, et al., 2014). EDs are widely available and popular among adolescents (Azagba, Langille, & Asbridge, 2014; Owens, Mindell, & Baylor, 2014). However, evidence consistently associates ED consumption with a range of negative physiological and behavioural health effects (e.g., Arria & O’Brien, 2011; Seifert, et al., 2013). The significant

* Corresponding author. School of Psychology, Faculty of Health, Deakin University, Geelong Waterfront Campus, Victoria 3220, Australia. E-mail address: [email protected] (B.M. Costa). http://dx.doi.org/10.1016/j.appet.2016.07.001 0195-6663/© 2016 Elsevier Ltd. All rights reserved.

harms associated with ED consumption has led Lithuania to institute a ban among those <18 years (Australian Associated Press, 2014, May 15). Given the current context of the lack of regulation of ED marketing and availability coupled with their popularity, ED consumption may pose a substantial risk of harm to adolescent health. Evidence of Australian adolescents’ ED consumption patterns is limited. The authors are aware of only two small qualitative studies published to date (Costa, Hayley, & Miller, 2014; O’Dea, 2003). O’Dea (2003) reported that 42% of a sample of 78 11e18 year olds from one New South Wales school had consumed an ED in the past fortnight for its taste, for energy, or when playing sport. More recently, Costa et al. (2014) found that most of their 40 12e15 year old focus group participants had consumed EDs at least once, with some consuming regularly them on a weekly basis. Internationally, the proportion of adolescent ED consumers ranges 20e62% of samples across individual studies (e.g., Azagba et al., 2014; Breda et al., 2014; Burrows, Pursey, Neve, & Stanwell, 2013; TerryMcElrath, O’Malley, & Johnston, 2014). For example, 62% of 9118 Canadian secondary students with a mean age of 15 years had consumed EDs at least once during the past 12 months, and 20% reported consuming them monthly or more frequently (Azagba et al., 2014). Thirty percent of a representative national American

B.M. Costa et al. / Appetite 105 (2016) 638e642

sample of 21,995 adolescents in grades 8e12 reported consuming EDs daily, compared to 40% who reported daily soft drink consumption (Terry-McElrath et al., 2014). ED consumption among Saudi Arabian adolescents appears similarly high, with approximately 55% of 1061 12e19 year olds consuming them weekly or more frequently (Musaiger & Zagzoog, 2014). Higher ED consumption rates have been found among adolescent males compared to females (Azagba et al., 2014; Gallimberti et al., 2013; Ludden & Wolfson, 2010; Temple, Dewey, & Briatico, 2010), and adolescents from disrupted homes (Azagba et al., 2014; Gallimberti et al., 2013). ED consumption has additionally been associated with adolescent risk taking behaviours including tobacco, alcohol and marijuana use, and sensation seeking (e.g., Azgaba et al., 2014; Gallimberti et al., 2013), including among those as young as 12 years of age (Gallimberti et al., 2013). In the only longitudinal study of its kind identified, young adolescents’ frequency of ED consumption was found to predict an increased frequency of alcohol use 16 months later, especially among those exposed to low parental monitoring (Miyake & Marmorstein, 2015). Such associations have yet to be tested among Australian adolescents, but are assumed to be comparable given the availability and popularity of EDs in Australia are similar as in other parts of the world. The main ED ingredients are caffeine and sugar. Regular caffeine consumption among children and adolescents has consistently been associated with headaches, anxiety, impaired sleep, daytime sleepiness, and juvenile depression (Benko et al., 2011; James, Kristjansson, & Sigfusdottir, 2011; Ludden & Wolfson, 2010). High caffeine use can lead to toxicity and, among habitual consumers, tolerance and addiction (Breda et al., 2014). High sugar sweetened beverage consumption contributes to weight gain, obesity, type 2 diabetes, dental caries and tooth erosion, and poor nutrition (Hafekost, Mitrou, Lawrence, & Zubrick, 2011; Pomeranz, Munsell, & Harris, 2013). Furthermore, EDs have been linked to a range of additional health harms among adult ED consumers, including heart palpitations, jitteriness (Malinauskas, Aeby, Overton, Carpenter-Aeby, & Barber-Heidal, 2007), sleep difficulties (Nordt et al., 2012), anxiety, gastric disturbance, nausea, and elevated blood pressure (Gunja & Brown, 2012). Preliminary evidence suggests adolescent ED consumers also experience these health effects (Costa et al., 2014; Temple et al., 2010). Significant growth and development occurs during the adolescent stage. ED consumption may compromise the proper nutrition and adequate sleep necessary for optimal growth during this period. The long-term impact of regular ED consumption and associated symptoms on adolescent health has yet to be established. 1.1. Current study This study examined ED consumption patterns among a group of Australian adolescents aged 12e18 years. We investigated characteristics of adolescent ED consumers, the extent to which adolescent ED consumers experienced short term negative physiological symptoms, and perceptions regarding the sale and consumption of EDs. 2. Method 2.1. Participants The sample comprised 399 adolescents (64% male) aged 12e18 years (M ¼ 14 years, SD ¼ 1.28) in school Years 7e10 from a regional Victorian town in Australia. Participants were recruited from four schools using a convenience sampling strategy. The majority of

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participants (71.7%) were from an elite, co-educational private school, an additional 18.5% were from a private all-boys Catholic school, 8.6% were from a co-educational public secondary school, and 1.2% were from an alternative secondary education setting for youth with complex needs or mental health issues at risk of school disengagement. 2.2. Procedure Approval for conduct of the study was obtained from the University ethics committee, the Victorian Department of Education and Early Childhood Development (DEECD), and the Catholic Education Office Melbourne. Six secondary schools were initially approached to participate, five consented to participate, and four provided completed student surveys. All students in Years 7e10 at participating schools were invited to participate by a liaison school staff member. Liaisons were provided with survey packs, containing a Plain Language Statement, consent form, and survey, to distribute to participating students. Surveys were provided in paper and electronic form dependent on school and student preferences. Electronic surveys were created and hosted by Survey Monkey, an online survey platform. Students who returned signed parental consent forms within a two-week period completed the survey independently in a group setting school hours, under teacher supervision. Data collection occurred over a four month period in 2014. A total of 583 students from Years 7e10 across participating schools were invited to participate. Of the 443 surveys received, 399 contained complete useable data, indicating an overall response rate of 76% and a final response rate of 68.4%. Most (95%) participants completed the survey electronically. 2.3. Measures We developed a survey for the purposes of this study based on the findings of previous research (e.g., Costa et al., 2014; Gallimberti et al., 2013). The 16-item survey collected information related to adolescents’ awareness of the recommended ED consumption guidelines, their own ED consumption patterns, experience of physiological symptoms, and demographic characteristics. An ED was defined as a standard 250 mL caffeinated drink advertised as providing energy and enhancing performance that was different from soft drinks, sports drinks and coffee. Belief about age-appropriate energy drink consumption. Participants indicated the number of standard EDs per day they considered appropriate for children <12 years, adolescents 12e18 years, and adults >18 years to consume. Energy Drink consumption patterns. Participants indicated the frequency with which they usually consumed one or more EDs on a nine point rating scale ranging from Never to More than once a day. We classified participants as ED consumers (any consumption) or non-consumers (never consumed). For analysis purposes we further differentiated ED consumers on the basis of whether or not they indicated consuming EDs at least once per month. ED consumers were asked to indicate the age at which they consumed their first ED, the number of EDs they usually consumed per session. Consumers also rated how often they drank more than two EDs on a single occasion (exceeding the recommended daily limit for adults) by selecting one of nine ordinal ratings ranging from Never to More than once a day. For analysis purposes we differentiated consumers on the basis of whether they reported exceeding consumption recommendations never or at least once. Experience of physiological symptoms. Previous research (e.g., Costa et al., 2014; Nordt et al., 2012; Temple et al., 2010) identified eight common short-term physiological symptoms associated with

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ED consumption: racing heart; rapid speech; upset stomach; insomnia; anxiety/agitation; tremors; heart palpitations; and visual disturbances. ED consumers rated how frequently they experienced each symptom during or immediately following ED consumption using a five-point rating scale that ranged Never e Always. Demographic characteristics. Demographic characteristics collected included participants’ gender, age, school year level, residential postcode, and number and age/s of any siblings.

ED consumption. The mean age EDs were first consumed was 10.5 years (SD ¼ 2.97); 53% of participants had consumed their first ED prior to age 12. EDs were consumed rarely by 50.5%, monthly by 32.1%, and at least weekly by 17.4% of those who had ever had an ED. Participants consumed zero to seven EDs per session (M ¼ 1.43, SD ¼ 0.92). A third of consumers (36.2%) had exceeded the recommended daily limit of two standard EDs for adults, and did so rarely (47.5%), monthly (11.3%), or weekly (6.4%). 3.2. Characteristics of energy drink consumers

2.4. Analysis Descriptive statistics were calculated for all variables. We conducted two-way chi square test for independence analyses to examine gender differences, and one-way ANOVA analyses to examine age differences, on key variables (frequency of consumption, ever exceeded recommended adult daily limit) among ED consumers. Additionally we explored differences in beliefs about age-appropriate ED consumption between consumers and nonconsumers by one-way ANOVA tests. Finally we conducted a series of bivariate correlations to test for associations between physiological symptoms and key ED consumer characteristics. Specifically, Pearson’s correlations were applied for continuous variables (age), Spearman’s rho correlations for ordinal variables (number of EDs consumed per session), Point Biserial correlations for discrete dichotomous variables (gender), and Biserial correlations for dichotomous variables derived from continuous data (monthly versus less frequent consumption). Two-tailed hypothesis tests were conducted for all analyses with p-values < 0.05 considered statistically significant. IBM SPSS version 22 was used for all analyses. 3. Results 3.1. Energy drink consumption patterns Table 1 provides a summary of ED consumption patterns within the sample. Of the 399 participants, 224 (56.1%) reported lifetime

A significantly greater proportion of ED consumers were male (73%) than female (23%; c2(1) ¼ 45.87, p < 0.001). However, male and female consumers did not differ in the frequency with which they consumed EDs (monthly/less than monthly; c2(1) ¼ 0.2.54, p ¼ 0.11), or whether or not they had exceeded the recommended daily limit of two EDs/day (c2(1) ¼ 1.34, p ¼ 0.25). Of consumers, 19.3% were aged 12e13 years, 42.5% were aged 14e15 years, and 38.2% were aged 16e18 years. A one-way ANOVA found that ED consumers were, on average, older than nonconsumers (F (1,381) ¼ 19.27, p < 0.001, partial h2 ¼ 0.05, b ¼ 0.99). 3.3. Physiological symptoms associated with energy drink consumption Just over half (53.2%) of consumers reported experiencing at least one physiological symptom following ED consumption. As shown in Table 2, the most frequently reported symptom was a racing heart, followed by rapid speech, an upset stomach, insomnia, anxiety/agitation, heart palpitations, and visual disturbance. Twenty-two percent of consumers reported experiencing ‘Other’ symptoms. These included ‘dizziness’, feeling ‘stimulated’, ‘bloated’, and ‘tiredness/energy loss’. A number of significant small associations were found between physiological symptoms and key consumer characteristics. With the exception of tremors, consuming more than two standard EDs/ day was weakly positively correlated with experiencing all physiological symptoms (r ¼ 0.18e0.29, all p < 0.05). The number of EDs

Table 1 Adolescent energy drink consumption characteristics (n ¼ 224).

% ED consumera Age first ED consumed (M ¼ 10.5, SD ¼ 2.97) <12 12e16 16e18 Frequency of any consumption (n ¼ 397)b Never Rarely, less than once a month Monthly or more Weekly or more % participants who exceeded consumption recommendations at least once c (n ¼ 221) Frequency of exceeding consumption recommendationsc (n ¼ 221) Never Rarely, less than once a month Monthly or more Weekly or more Number of EDs usually consumed per session (n ¼ 208)d 1 2 3 Notes. ED ¼ energy drink. a Consumed at least one ED. b Two participants did not respond to this question. c Daily limit of two standard 250 mL EDs for adults. d Range 0e7 (median and mode ¼ 1).

N

Sample %

224

56.1

ED consumer %

105 94 0

26.3 23.6 0.0

52.8 47.2 0.0

173 113 72 39 144

43.4 28.3 18 9.8 36.2

0.0 50.5 32.1 17.4 65.2

77 105 25 14

19.4 26.4 6.3 3.5

34.8 47.5 11.3 6.4

145 50 13

36.3 12.5 3.4

69.8 24.0 6.2

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Table 2 Bivariate correlations between adolescent energy drink consumer physiological symptoms, demographics, and consumption characteristics. Symptom

Racing heart (n ¼ 214) Rapid speech (n ¼ 214) Upset stomach (n ¼ 213) Insomnia (n ¼ 213) Anxiety/agitation (n ¼ 213) Tremors (n ¼ 212) Heart palpitations (n ¼ 211) Visual disturbances (n ¼ 213)

Consumers per symptom

Consumer characteristics (correlation coefficients)

N

%

Gender

Age

Monthly use

High use

EDs per session

86 74 60 47 45 38 33 31

40.8 34.7 28.2 22.1 21.1 17.9 16.1 14.6

0.04 0.06 0.01 0.15* 0.05 0.08 0.10 0.06

0.12 0.01 0.08 0.10 0.02 0.10 0.08 0.13

0.06 0.10 0.05 0.11 0.01 0.06 0.02 0.02

0.21* 0.29* 0.21* 0.20* 0.27** 0.14 0.19* 0.18*

0.16* 0.18* 0.05 0.03 0.07 0.18* 0.10 0.08

Notes. *p < 0.05, **p < 0.01, all two-tailed. ‘Symptoms’ were entered into correlation analyses as continuous variables. Pearson’s correlations were applied for ‘Age’ (continuous variable), Spearman’s rho correlations for ‘EDs per session’ (ordinal variable), Point Biseral correlations were applied for gender (discrete dichotomous variable), and Biserial correlations were applied for ‘Monthly use’ and ‘High use’ (dichotomous variables derived from continuous data). For dichotomous variables, 1 ¼ ‘Monthly use’, ‘High use’, and ‘Female’; 0 ¼ ‘Less than monthly use’, ‘No high use’, and ‘Male’. For ‘EDs per session’, 1 ¼ One ED per session; 2 ¼ Two EDs per session; 3 ¼ Three or more EDs per session).

consumed per session was positively correlated with four symptoms (racing heart, rapid speech, tremors) (r ¼ 0.16e0.18, all p < 0.05). Except for a positive association between being female and experiencing insomnia (r ¼ 0.15, p < 0.05), gender, age, and frequency of ED consumption were not correlated with any physiological symptom. 3.4. Belief about age-appropriate energy drink consumption The number of EDs participants considered appropriate for children, adolescents, and adults to consume per day are shown in Table 3. The proportion of participants who perceived as appropriate the consumption of one or more EDs per day increased with the target age group, from 54% for children <12 years, to 90.5% for adolescents, and 96.0% for adults. Further, 16.9% and 34.0% of participants considered it appropriate for adolescents and adults, respectively, to consume three or more EDs a day, in excess of the daily recommended limit for adults. In comparison to non-consumers, ED consumers uniformly perceived a higher number of EDs to be appropriate for daily consumption by children (F (1,381) ¼ 8.01, p < 0.01, partial h2 ¼ 0.02, b ¼ 0.81), adolescents (F (1,381) ¼ 15.25, p < 0.001, partial h2 ¼ 0.04, b ¼ 0.97), and adults (F (1,381) ¼ 6.58, p < 0.01, partial h2 ¼ 0.02, b ¼ 0.73). 4. Discussion In this study, we examined ED consumption patterns among an Australian adolescent sample. More than half the adolescents sampled reported consuming EDs, consistent with previous Australian (Costa et al., 2014; O’Dea, 2003) and international (e.g.,

Table 3 Perceived appropriate number of standard energy drinks/day for three age groups. EDs per session

0 1 2 3a 4 Total Mode Range

Children (<12 yrs)

Adolescents (12e18 yrs)

Adults (18 yrs)

N

%

N

%

N

%

184 161 27 12 e 384

46.1 40.4 6.8 2.9 e 96.2

38 164 113 44 23 382

9.5 41.2 28.3 11.0 5.9 95.7

16 91 124 74 68 373

4.0 22.8 31.1 18.5 15.5 93.5

0 0e7

1 0e11

2 0e11

Notes. ED ¼ energy drink, where one standard energy drink ¼ 250 mL can. a Defined as  3 for children.

Azagba et al., 2014) findings. Male adolescents (e.g., Gallimberti et al., 2013) and adults (e.g., Miller, 2008; Trapp et al., 2014) have been found more likely to consume EDs than females. Similarly, a greater proportion of the current ED consumers were male than female. While half of all consumers drank EDs rarely, one in three drank them monthly, and one in six drank them weekly, similar to frequencies reported among American (Kumar, Park, & Onufrak, 2014) and Canadian (Azagba et al., 2014) adolescents. More than a third of ED consumers had exceeded the recommended daily limit for adults of two standard serves/day at least once, and this was associated with a range of physiological symptoms. This finding is concerning given that the physiological and behavioural effects of caffeine on children and adolescents are suspected to be harmful (ANZFA, 2000). Furthermore, sugar sweetened beverage consumption has been shown to exacerbate health concerns and diseases such as obesity and type 2 diabetes (Hafekost et al., 2011; Pomeranz et al., 2013). The long-term impact of regular high ED consumption has yet to be examined. The current study found that ED consumption prior to age 12 was common, with 10.5 years the average age of first consumption. This finding is consistent with previous research (e.g., Costa et al., 2014; Gallimberti et al., 2013), but inconsistent with ED manufacturers’ assertion that EDs are not marketed to nor consumed by those aged <12 years. While many adolescents are aware of ED brands, advertisements, and promotional activities, some adolescents (particularly those <15 years) are unaware that EDs are functionally distinct from other drink types such as sports drinks like Gatorade (Costa et al., 2014). There was wide variability in beliefs about the appropriate number of EDs that could be consumed per day. While the maximum number of EDs considered appropriate was greater for adolescents and adults, than for children <12 years, many participants considered it appropriate for all age groups to consume more than the recommended limit of two EDs/day for adults. These findings indicate a lack of awareness of the current recommendation that EDs are not appropriate for children, and the need for clearer information and education about the potential harm of EDs for children and adolescents. A range of factors likely influence adolescents’ ED consumption, including the home environment. Through role modelling, providing access and supply, and communicating health messages, parents are a key influence on children’s and adolescents’ food and beverage consumption patterns (e.g., Van Lippevelde et al., 2013; Wyse, Campbell, Nathan, & Wolfenden, 2011). Parents have been reported to consume EDs as well as supply and encourage them for their adolescents’ consumption (Costa et al., 2014). Deliens, Clarys, de Bourdeaudhuij, and Deforche (2015) recently found that

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perceived personal control, strict family rules against ED consumption and lower perceived availability of EDs were each associated with a lower rate of ED consumption among Belgian university students. Further research is needed to investigate the role parents play in adolescents’ consumption of EDs. Parentfocused interventions have previously been found effective for addressing child and adolescent health behaviours, including dietary intake (e.g., Bean, Wilson, Thornton, Kelly, & Mazzeo, 2012) and alcohol use (e.g., Doumas, Turrisi, Ray, Esp, & Curtis-Schaeffer, 2013), and hence may be an appropriate approach to reducing child and adolescent ED consumption. The current study has a number of limitations. Firstly, the findings are based on a small homogenous sample from one region. School recruitment targeted a range of schools in high and low SES areas, however a high SES was overrepresented in the final sample. Azagba et al. (2014) and Temple et al. (2010) reported that SES was not significantly associated with adolescent ED consumption patterns, therefore the skewed SES in this sample may be of limited concern. Further research should examine ED consumption patterns among a larger and more diverse sample of Australian adolescents. Secondly, findings relied on retrospective recall and estimation of usual intake, and may not accurately reflect adolescent ED consumption patterns. Further, while survey completion was conducted independently under teacher supervision it nevertheless occurred in a group setting. Therefore it is possible that the presence of one’s peers influenced responses to an unknown degree. Food and drink diary methods, for example using mobile device application, may more accurately capture ED consumption patterns, while allowing researchers to study the contexts of consumption in greater detail. In summary, this study found preliminary evidence that consumption of EDs is common among Australian adolescents, and is associated with first consumption prior to age 12, experience of physiological symptoms, and variability in the belief regarding the number of EDs/day considered appropriate for different age groups. These results add to the growing body of evidence regarding adolescent ED consumption and the detrimental impact of EDs on adolescent health. This study highlights the urgent need for regulation and restriction of EDs around children’s and adolescents’ consumption. As a first step, education around the potential harm of EDs for young consumers is needed, beginning at home. Acknowledgement The authors wish to thank the students and school staff who participated in this study. References Arria, A. M., & O’Brien, M. C. (2011). The “high” risk of energy drinks. JAMA, 305, 600e601. Australia New Zealand Food Authority. (June 2000). Report from the expert working group on the safety aspects of dietary caffeine. Australia New Zealand Food Authority. Australian Associated Press. (2014, May 15). Lithuania bans energy drinks for minors. Australia: Special Broadcasting Service (SBS). Retrieved from http://www.sbs. com.au/news/article/2014/05/15/lithuania-bans-energy-drinks-minors. Azagba, S., Langille, D., & Asbridge, M. (2014). An emerging adolescent health risk: Caffeinated energy drink consumption patterns among high school students. Preventative Medicine, 62, 54e59. Bean, M. K., Wilson, D. B., Thornton, L. M., Kelly, N., & Mazzeo, S. E. (2012). Dietary intake in a randomized-controlled pilot of NOURISH: A parent intervention for overweight children. Preventative Medicine: An International Journal Devoted to Practice and Theory, 55, 224e227. Benko, C. R., Farias, A. C., Farias, L. G., Pereira, E., Louzada, F. M., & Cordeiro, M. L. (2011). Potential link between caffeine consumption and pediatric depression.

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