Introduction
Energy drinks (ED) are popular beverages containing high levels of caffeine, sugar and additional ingredients with stimulating properties(Reference Bruzell and Carlsen1). ED are generally considered an energy-dense and nutrient-poor beverage(Reference Luger, Lafontan and Bes-Rastrollo2) and are usually advertised to give an extra boost in energy, mood, physical and cognitive performance. Examples of popular ED brands sold in Norway are Red Bull, Battery, Burn and Coca-Cola Energy to mention some(Reference Wictoresen and Musk3). ED have become a central part of partying and sport culture, especially among adolescent boys who report that they use ED to enhance their sports performance(Reference Breda, Whiting and Encarnacao4,Reference Visram, Cheetham and Riby5) . In Norway, the sales of ED have increased markedly in recent years with more than 62 million litres sold in 2021 only(6).
Adolescents are exposed to marketing of ED through different channels such as online gaming, TV, social media, advertisements of sporting events and sponsorship contract (e.g. athletes, football teams)(Reference Hammond and Reid7–Reference Marinoni, Parpinel and Gasparini9). According to the cross-sectional study by Buchanan et al., a small group of young adults (n 359) who consumed ED were significantly more exposed to digital marketing of ED, than the non-ED consumers(Reference Buchanan, Yeatman and Kelly10). In the same study, only engagement with digital marketing, when comparing to exposure and engagement of other types of marketing, significantly increased the likelihood of consuming ED when controlling for other covariates (age, sex, socio-economic status, student and work status, perceived significant others’ acceptance of their ED use). Digital marketing of ED has proven to be effective in persuading young adults to purchase and consume ED(Reference Buchanan, Kelly and Yeatman11). In addition, online marketing could have a greater impact on young adults who are less aware of the possible negative health outcomes of consuming ED(Reference Buchanan, Kelly and Yeatman11). Lately, digital marketing through social media has been linked to unhealthy food consumption among children(Reference Alvy and Calvert12,Reference Kelly, Bochynska and Kornman13) , as exposed children increased their intake of calories and unhealthy snacks(Reference Coates, Hardman and Halford14).
Boys have been shown to consume larger amounts of ED than girls, which could be due to the masculinity of advertisements and marketing of ED and how potential effects of ED consumption include better physical and sports performance(Reference Hammond and Reid7,Reference Nowak and Jasionowski15) . In previous studies, we found that the typical ED consumer was indeed a boy who had a lower socio-economic status and had spent much of his free time on screen-related activities(Reference Kaldenbach, Strand and Solvik16,Reference Degirmenci, Fossum and Strand17) . This is in line with other studies which have found positive associations between sedentary behaviour and screen time activities(Reference Nuss, Morley and Scully18,Reference Al-Hazzaa, Al-Sobayel and Abahussain19) . Yet positive associations between increased physical activity and ED consumption has also been found, which might suggest the use of ED as a refreshment or even a booster during sport activities(Reference Degirmenci, Fossum and Strand17,Reference Koivusilta, Kuoppamäki and Rimpelä20) .
Despite the positive marketing of ED, several recent studies have found potential negative effects of ED consumption. ED consumption has been found to be associated with heart palpitations(Reference Busuttil and Willoughby21), higher systolic blood pressure and increased QT interval (the time it takes for the ventricles of the heart to contract and fully relax)(Reference Cox22,Reference Fletcher, Lacey and Aaron23) . In addition, increased headache and sleeping problems have also been linked to ED consumption ranging from a single high dose (946 ml ED with 320 mg caffeine) to daily use(Reference Koivusilta, Kuoppamäki and Rimpelä20,Reference Huhtinen, Lindfors and Rimpelä24) . These negative effects are most likely related to the high caffeine content of ED, though the combination of ingredients found in ED might also play a role. According to a review by the Norwegian Scientific Committee for Food and Environment, an adolescent with an average weight of 50 kg would be at risk of sleep disturbance when consuming more than 70 mg/d of caffeine, which is approximately 500 ml of ED a day(Reference Bruzell and Carlsen1,Reference Zucconi, Volpato and Adinolfi25) .
At the moment, there are no regulations or legislations in Norway limiting adolescents from consuming ED(Reference Bruzell and Carlsen1). Social circumstances and parental attitudes towards ED consumption, either disapproving or encouraging consumption, have shown to affect ED consumption(Reference Visram, Cheetham and Riby5). Yet, broader knowledge on attitudes, habits and experience with ED consumption among adolescents is scarce. The aim of the present study was to describe the associations between experiences, attitudes and expectations of ED consumption related to the amount of ED consumed in the adolescent population.
Experimental methods
Study design and participants
Data from the Norwegian annual Ungdata survey were used for the study. Ungdata is a national youth survey aiming to survey adolescent health and is typically performed every third year in each of the Norwegian municipalities(Reference Degirmenci, Fossum and Strand17). The survey is administered by the Norwegian Social Research (NOVA) at Oslo Metropolitan University in a collaboration with the Regional Drug and Alcohol Competence Centres (KoRus). An electronic questionnaire is filled out during school hours by students in lower and upper secondary school (Grades 8–10 including ages 12–15 years and grades 11–13 including ages 15–19, respectively). Details regarding the data are available at https://ungdata.no/english/ (26).
The data used in the present study were collected in 2015 and 2016 and encompassed 15 913 adolescents between the ages of 13 and 19 years (57⋅9 % male, 38⋅8 % female). For the purposes of the current analysis, we chose to only include those who reported consuming ED.
Measures
The main outcome variable was average daily ED consumption. This was estimated from two questions: ‘How often do you drink energy drinks?’ with options on a seven-point scale from ‘never’ to ‘daily’, and ‘How much energy drink do you usually drink when you consume energy drinks?’ with options on a six-point scale from ‘one small can (ca 250 ml)’ to ‘several cans corresponding to more than 1⋅5 litres’. Respondents were defined as ED consumers if they answered the question ‘How often do you drink energy drinks?’ with the answer options ‘Once a month or less’ up to ‘daily’.
Adolescents were asked about their ED consumption regarding: (1) reasons for drinking ED; (2) experiences with ED consumption; (3) parental attitudes towards ED consumption and (4) circumstances when ED are usually consumed. Each statement could be answered with one of four incremental options from ‘not true’ to ‘very true’. The responses were dichotomised from four into two categories on all four topics: ‘disagree’ and ‘agree’.
Reasons for drinking ED were assessed by the following questions and statements: The question ‘To what extent do the following statements describe why you drink energy drinks?’ was followed by seven statements: ‘Because it tastes good’, ‘Because I need energy’, ‘Because I need to stay awake’, ‘Because my friends do it’, ‘To perform better in sports’, ‘To concentrate’, ‘To perform better in school’. Experiences with ED consumption were assessed using the question ‘How often do you experience any of the following after drinking energy drinks?’ followed by eight statements: ‘increased endurance/less tired’, ‘feel stronger/have extra energy’, ‘feel nervous’, ‘have difficulty sleeping’, ‘do not feel anything in particular when I drink energy drinks’.
Parental attitudes were assessed using the question ‘How well do the following statements fit regarding your parents’ attitudes towards energy drinks?’ followed by four statements: ‘my parents think it is OK that I drink energy drinks’, ‘my parents don't know that I drink energy drinks’, ‘my parents say that I shouldn't drink energy drinks’, ‘my parents have spoken to my about energy drinks’.
Circumstances when ED are usually consumed was assessed using the question ‘What do you usually do when you drink energy drinks?’ followed by eight statements: ‘I am with friends’, ‘I am at a party’, ‘I am on my way to/doing sports’, ‘I am at the youth club’, ‘I am on my way to or from school’, ‘I am gaming/using my computer’, ‘I am watching TV, movies or streaming’, ‘I am at home’.
All participants reported on sex (male, female), grade (8–13), in addition to the other background variables including leisure screen time, perceived family economy, centrality and physical activity. Leisure screen time was assessed using the question ‘Outside school, how much time do you normally spend on activities that involve looking at a screen (TV, computer, tablet, mobile phone) each day?’ with response options on a seven-point incremental scale ranging from ‘no time’ to ‘≥ 6 h’. The first three options of the variable leisure screen time were merged into one response of ‘≤2 h’ due to the relatively low number of respondents in each of these categories. Physical activity was assessed by the question ‘How often do you perform physical activity which gets you out of breath or makes you sweaty?’ with response options on a six-point incremental scale ranging from ‘never’ to ‘at least five times a week’. Perceived family economy was based on the question ‘has your family's economic situation been good or bad during the past two years?’, with five response options ranging from ‘always good’ to ‘always bad’. Finally, the Norwegian centrality index was used to define centrality which refers to an index of travel time to workplaces and service functions from all populated basic units. Group 1 contains the most central municipalities (highest index) and group 6 contains the least central (lowest index)(Reference Høydahl27).
Statistical analyses
We used linear regression models to estimate the crude and adjusted mean differences in ED intake in ml/d between the response categories from the different questions in the four categories: (1) reasons for drinking ED; (2) experiences with ED consumption; (3) parental attitudes towards ED consumption and (4) circumstances when ED is usually consumed. Responses to the different questions are presented with percentages while the regression coefficients are additionally presented with 95 % CIs. All estimates were adjusted for gender, grade (as a proxy for age), leisure screen time, perceived family economy, centrality and physical activity, but these estimates, which were chosen based on previous knowledge(Reference Kaldenbach, Strand and Solvik16,Reference Kaldenbach, Leonhardt and Lien28) , are not presented and were chosen a priori. The plot describing the association between the average daily intake of ED and the frequency of ED was generated using two-way fractional polynomials (‘twoway fpfit’ command in Stata) without adjustment for other variables. We used STATA version 17.0 for all statistical analysis(29).
Ethical standards disclosure
This study was conducted according to the guidelines laid down in the Declaration of Helsinki and all procedures involving research study participants were approved by the Norwegian Centre for Research Data (NSD). Participants do not have a unique identification number as data collection is done anonymously and does not contain any sensitive information. Therefore, no additional ethical approval was needed. Participants and their parents were informed that participation is voluntary, and parents had the ability to withdraw their children (<18 years of age) from participation. The present study was however additionally approved by the Data Protection Office at Innlandet Hospital Trust with the reference number 18778329.
Results
A total of 15 913 adolescents, 57⋅9 % male and 38⋅8 % female, responded to the questionnaire about habits, attitudes and experiences regarding ED consumption. There was an even distribution between the different grades, but with the lowest response rate in grade 13. Most of the participants lived ‘very central’ (69⋅1 %), and 25⋅5 % spent 3–4 h outside school on leisure screen time activities, but the majority were physically active 2–5 times a week (82⋅5 %). The baseline characteristics of the participants are displayed in Table 1.
Table 1. Background characteristics
There was a dose-response relationship between the average daily intake of ED and the frequency of ED consumption as shown in Fig. 1. Most responded that they consumed ED ‘because it tastes good’ (96⋅1 %), but also ‘because I need energy’ (47⋅1 %), ‘to stay awake’ (48⋅1 %), ‘to concentrate’ (20⋅4 %) and ‘to perform better in school’ (11⋅3 %) (Table 2). As an example, those who consumed ED to ‘perform better in school’ had an average intake of 193⋅8 ml daily which is 112⋅0 ml (adjusted) more than those who did not report to consume ED for this reason.
Fig. 1. Average daily intake of ED according to ED consumption frequency.
Table 2. Reasons for consuming ED
As seen in Table 3, most ED consumers reported that their parents think it is OK that they consume ED (78⋅1 %). Yet, more than 40 % of them responded that their parents had talked to them about ED and that their parents say that they should not drink ED. Approximately 17 % of the adolescents reported that their parents do not know that they drink ED.
Table 3. Parental attitudes towards ED consumption
The majority of ED consumers drink ED when they are with friends (59⋅9 %), are at home (54⋅4 %), are gaming (37⋅2 %), or are engaged in other screen-based leisure activities (36⋅2 %) (Table 4). The least reported circumstances were when they are at a youth club (11⋅7 %) or when they are doing sports (16⋅4 %).
Table 4. Circumstances when drinking ED
Among both ED consumers and high ED consumers, the majority responded that when drinking ED, they ‘do not feel anything in particular’ (65⋅9 %) (Table 5). However, 47⋅2 % ‘felt less tired’ after consuming ED and 33⋅9 % ‘felt stronger’. Adverse effects of ED consumption were in general infrequently reported, with the most common reported side effects being palpitations and sleeping difficulty among more than 10 % of the ED consumers.
Table 5. Experiences with ED consumption
Discussion
In this cross-sectional study on attitudes, habits and experiences with ED consumption among Norwegian adolescent, we found that the main reason for consuming ED was the taste, but also the need for energy to stay awake. Many of the adolescents felt more energised after consuming ED and most ED consumers were with friends when consuming ED.
Improved performance is a known marketing strategy for ED producers(Reference Buchanan, Yeatman and Kelly30). Indeed, in our study, many adolescents reported that they felt stronger and had more energy after consuming ED. Other studies have also found that adolescents, particularly boys, use ED to improve their performance(Reference Bunting, Baggett and Grigor31–Reference O'Dea33) and that adolescents who are physically active drink more ED. Yet, there are also studies that have demonstrated that adolescents who are very physically active are not typical ED consumers(Reference Erdmann, Wiciński and Wódkiewicz34).
Two-thirds of the adolescents in our study reported that they do not feel anything in particular when drinking ED. This is reflected by the infrequent reporting of side effects such as palpitations, anxiety, nervousness and sleeping difficulties. Moreover, our finding of the majority of participants reporting to drink ED mainly because it tastes good might suggest that there is still limited knowledge of the effects of ED consumption, or that they do not care about the content and possible consequences of frequent ED consumption. Indeed, previous studies have demonstrated that adolescents who consume ED have limited knowledge of the possible consequences of ED and are therefore more likely to consume ED(Reference Visram, Cheetham and Riby5,Reference Costa, Hayley and Miller32) .
Parental attitudes towards ED consumption can affect adolescents’ habits regarding ED consumption in both directions, influencing them to consume or not. Previous studies have showed that parents play an important role regarding ED consumption where they spark the idea of ED consumption by talking to the adolescents about ED(Reference Costa, Hayley and Miller32). In the present study, many adolescents reported that their parents had talked to them about ED consumption, and several of the adolescents not consuming ED reported that they did not drink ED because their parents did not allow it. Interestingly, neither talking about nor reporting trying to refuse ED consumption was associated with ED intake. Furthermore, most adolescent ED consumers reported that their parents think it is OK that they drink ED. The adolescent period has been demonstrated to be an important period of influence for later food consumption and habits(Reference Lipsky, Haynie and Liu35,36) . Therefore, potential interventions regarding ED consumption might ultimately be most influential in this period.
We found that most ED consumers where either with friends, gaming or doing other screen-based leisure activities when consuming ED. This is in line with previous findings where a social situation, such as being with friends at home or outside, was a common context of ED consumption(Reference Visram, Cheetham and Riby5). One could speculate that ED consumption increases among adolescents because of the known exposure to digital marketing of ED(Reference Buchanan, Yeatman and Kelly30), through gaming and social media. Moreover, because of these social situations and exposures, ED might have become a common drink to consume just like any other non-alcoholic beverage.
Strengths and limitations
The main strength of the present study is the large and wide-reaching sample of adolescents across Norway. However, a limitation to the study is the fact that we could not include open questions regarding the reasons for ED use. If the inclusion of such questions had been possible, we could have captured aspects of ED use that our structured questionnaire missed. Such information could also have been obtained using a qualitative or mixed design. Other limitations of the study are that the data are self-reported and are therefore subject to recall-bias.
Conclusion
The study adds new information on experiences with ED, attitudes towards ED and habits around consumption of ED in adolescents. The experiences and habits regarding adolescent ED consumption are complex and to a certain degree contradictive, yet many adolescents still choose to consume ED in relatively large amounts according to our findings. This information is valuable for strategy and policymakers, next to healthcare professionals and others working with adolescents, when addressing the potential negative affects which comes with ED consumption towards adolescents.
Acknowledgements
The authors would like to thank NOVA (The Norwegian Social Research) for granting access to the data from the ‘Ungdata, 2010–2019’ surveys used in the present study.
This study was funded by Innlandet Hospital Trust (project number: 150377). The funding source did not play any role in the design and implantation of the study; collection, management, analysis or interpretation of the data; and preparation, review or approval of the manuscript.
S. K., T. A. S. and M. H.-A., conceptualised the study, acquired the data, analysed the data, drafted and wrote the manuscript. They have all read and approved the final manuscript.
No conflict of interest to declare.
Data may be obtained from a third party and are not publicly available. The data supporting our study are available from the Norwegian Centre for Research Data (NSD) and were used under license for the present study. The Ungdata survey is funded by The Norwegian Directorate of Health. Anonymous data have been made available for the authors by NOVA through NSD—the Norwegian Centre for Research Data. Neither NOVA, The Norwegian Directorate of Health nor NSD are responsible for the analyses or interpretation of the presented data.
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