Abstract
Energy drinks have become a popular beverage worldwide. This review was carried out to have an overview among adolescents and emerging adults in the Gulf Co-operation Council states about energy drinks consumption rates and other related issues such as starting age and patterns of energy drink consumption.
The Medline and Embase databases were searched separately using different terms such as energy drinks, energy beverages, and caffeinated drinks. Data related to the rates of energy drinks use were entered in STATA for statistical analysis. Then, these data were used to conduct meta-analysis to estimate the rate of energy drink consumption. Overall, meta-analysis results showed that the estimated rates of energy drinks consumption is 46.9% (95% CIs, 33.2 −66.1; nine studies) with I-square 3.7%. Findings indicated that individuals start to consume energy drinks at approximately 16 years old, and males were found to consume energy drinks more frequently than females. Results from this review carry several recommendations for policy and enforcement, public education and research that can help policy and decision makers to achieve the goal of safer use of energy drinks.
Introduction
Energy drinks have become a popular beverage worldwide, used commonly by adolescents and young adults of 18–34 years old. In 2008, energy drinks comprised roughly 42.4% of the functional drinks market, with total revenue of $11.8 billion USD. 1 At first, energy drink companies primarily targeted athletes; however, as the energy drink market grew and expanded vastly, it shifted its target to adolescents and young adults between the ages of 16 and 35 years.2,3
The main active ingredient in the energy drinks is caffeine, and many other components are often added to prepare the “energy blend” such as sugar, taurine, glucuronolactone, guarana and B vitamins. 4 Adolescents and young adults consume energy drinks because of their temporary benefits including increasing alertness, enhancing mental and physical energy, and improving mood.5,6 However, many studies identified side effects associated with excessive caffeine intake by adolescents such as irritability, sleep impairment, cardiovascular symptoms and nervousness. 6 Researchers associated energy drink intake among youths with specific problem behaviours such as smoking and substance use.6,7 Arria et al. worryingly found that even after adjusting for confounders such as heavy alcohol drinking patterns, consuming energy drinks confer a risk for alcohol dependence. 5 This might be attributed to two main reasons: (1) the popularity of mixing alcohol with energy drinks; and (2) the use of the high levels of caffeine available in some energy drinks to manage hangover effects from alcohol use. 5
Researches and proactive steps to protect the health of the public have been carried out in the Western region in terms of energy drink consumption and related side effects. Yet, in the Gulf Co-operation Council states, there is dearth of studies focusing on the health and safety of energy drinks' consumption. However, as a consequence of the few studies carried out in Saudi Arabia, the cabinet meeting approved number of actions to regulate energy drinks consumption and enhance its safety (see Appendix 1).
The aims of this study are:
To have an overview among adolescents and emerging adults aged between 18 and 34 years in the Gulf Co-operation Council states of:
The starting age of energy drink consumption The rough estimated prevalence rates of energy drink consumption The patterns of energy drink consumption Awareness of energy drink contents and associated side effects To identify differences between males and females in terms of energy drink prevalence and pattern of use To identify motivations for energy drink consumption To identify any association between energy drinks and substance use (e.g. smoking, alcohol and drugs) To provide recommendations that aim at reducing side effects associated with energy drink consumption, and promote their safe use among the public.
Method
Approval was not needed as this study was a review, with no primary data collection.
Review questions
A literature search was carried out to identify information relevant to the following review questions among adolescents and young adults in the Gulf Co-operation Council states:
What is the starting age of energy drink consumption? Is there any gender differences in the consumption of energy drinks? What is the estimated rate of the prevalence of energy drink consumption? What are the patterns of energy drink consumption? What is the level of awareness of energy drink contents and associated side effects? What are the motivations for energy drink consumption?
The Medline and Embase databases (via Dialog and Ovid, respectively; 1950 to July 2014 (Medline), and 1947 to July 2014 (Embase)) were searched separately on 15 July 2014. The search was carried out using terms identified from PICOS deconstruction (population, intervention and outcomes) of the above review questions such as energy drinks, energy beverages, caffeinated drinks, side effects, motivation, and inspiration for use. Further relevant studies were identified by searching the reference lists of the database-derived papers, contacting expert investigators.
Measures
Rate of energy drink consumption
Any reported rate of energy drink consumption including: (1) ever consumed energy drinks; (2) consumed energy drinks once the past 12 months; (3) consumed energy drinks the previous month; (4) consumed energy drinks the previous week; and (5) consume energy drinks on a daily basis.
Patterns of energy drink consumption
Any reported patterns of energy drink consumption among regular users who consume energy drinks on a daily basis and/or irregular users who might use 1–2 or 2–3 cans per week/month/year.
Selection
The titles and abstracts were evaluated by one reviewer to determine eligibility for full screening. Studies that utilised designs from a pre-determined list of acceptable methods – including randomised controlled trial and observational study (cross sectional, quasi-experimental and interventional) – were included. No limitations on publication type, publication status, study design or language of publication were imposed. However, we did not include secondary reports such as review articles without novel synthesis. The inclusion criteria demanded that the study population be adolescents and young adults from both genders and of a Gulf Co-operation Council states.
Ten studies were identified as suitable for full review, and were each considered by two reviewers. One study was excluded, 8 by consensus, because data were not (fully) available.
Data extraction/quality assessment
The data captured for each study included data relating to (1) objective of the study; (2) methods (study design, sampling, participants’ characteristics, and setting); and (3) outcomes.
Data synthesis
Data related to the prevalence of energy drink use were entered in STATA version 10 for statistical analysis. Then, these data were used to conduct meta-analysis to estimate the rate of energy drink consumption, and the degree of heterogeneity was assessed between the studies statistically using meta-analysis to obtain an I-square value. The majority of the studies included were observational; therefore, the value of I-square is expected to be high due to many factors including sampling, and methodological and statistical variation of the studies. Random effect method was used to account for the anticipated heterogeneity. Subgroup analysis was performed to assess the difference in consuming energy drinks between school and university students. Also, the measures of uncertainty (95% confidence intervals) were calculated.
Results
Summary of the studies included in the review.
Age and gender of energy drinks users
Three studies9–11 reported the average age at first consumption as being roughly 16 years. However, in the study carried out in the UAE among medical students, the majority of participants (92%) declared that they started consuming energy drinks from 15 years.
12
Ibrahim et al. stated that males started drinking energy drinks at a younger age compared to females (16.1 ± 2.8 years vs. 18.3 ± 2.9 years,
Musaiger et al. found that males consume energy drinks more frequently than females (
Prevalence rates and patterns of energy drink consumption
Overall, meta-analysis results showed that the estimated rate of energy drink consumption is 46.9% (95% CIs, 33.2–66.1; nine studies) with I-square = 3.7%. Subgroup analysis by setting shows that the highest estimate of energy drink consumption was found in schools, 65.3% (95% CIs, 41.6–102.3; four studies), followed by universities, 29.3% (95% CIs, 17.2–50.0; five studies). These differences in the summarised estimates of energy drink consumption between schools and universities are statistically significant (
Four studies documented the pattern of energy drink consumption.7,9,10,13 The first study
7
found that the majority of participants aged between 12 and 19 years who consume energy drinks (179 males (31.9%) and 123 females (24.7%)) use one to two cans per week. Worryingly, the study found also 125/562 (22.2%) of males and 20/499 (4%) of females consume >5 cans of energy drinks per week. The second study
9
indicated that 4.6% of regular users of energy drinks consumed them more than once daily and about 20.3% consumed them on a daily basis, while 15.2% used energy drinks two to three times per week. The third study
13
declared that 16.3% of males and 8.5% of females consume energy drinks more than three days per week. The final study carried out by Alsunni et al. showed that 107 of 153 (69.9%) males compared to 27 of 33 (38.4%) females consume energy drinks on an irregular routine (
Interestingly, a statistically significant difference was found between smoking and energy drink consumption by one study.
9
Energy drink consumption was much higher among smokers (59.6%) compared to non-smokers (27.1%) (
Awareness of the content of energy drinks and associated side effects
Consistently, in the four studies7,10,12,14 that assessed participants’ awareness of the content of energy drinks, approximately half the number of the study sample were not aware of the active ingredients in the energy drinks. Regarding awareness of the caffeine content, in one of the studies, 53.2% of males and 48.3% of females knew that energy drinks contain caffeine (
One study assessed the participants' awareness of the side effects associated with the consumption of energy drinks. 14 It indicated that 72% of the participants knew about the effect of energy drinks on blood pressure, 77% knew the effect on blood sugar level, and 69.2% knew the effect on heart rate. 14
Three studies reported9,14,16 that side effects resulted from energy drink use among school and university students. Ibrahim et al. reported that 31.6% of regular energy drink users experienced adverse effects after energy drink consumption. 9 Of these adverse effects, 30.4% of users reported having heart palpitation, 29.5% having insomnia, 19.1% having frequent micturition, 16.2% having headache and 4.8% having jolt and crash episodes. 9 A jolt and crash episode is known as the experience of sudden burst, or jolt of energy, which only lasts a few hours before the consumer experiences a debilitating crash. 9 Aluqmany et al. found that 22.4% of energy drink consumers developed mood changes, 60% stated that they became more energetic, and 29.1% stated developing body changes such as change in the voice tone, and menstrual changes. 14 Similar side effects were reported by Bawazeer et al., in which 20% of university students consuming energy drinks experienced heart palpitation, 6% experienced headache, 3% reported nervousness, and 4% reported nausea and vomiting. 16
Motivations for energy drink consumption
Summary of the motivations for consuming energy drinks.
Discussion
Demographics of energy drink users
Findings from the reviewed studies indicated that individuals start to consume energy drinks at approximately 16 years old, yet some researches, for instance Kilani et al., found that females started consuming energy drinks earlier than 16 years. 11 Jacob et al. reported that the majority of energy drink users started drinking them from 15 years of age. 12 In the same line, it was reported in a study carried out in Canada that the average age of consuming energy drinks among secondary school students is 15.2 years. 6 However, Ballard et al. reported the consumption of energy drinks at younger ages, starting from 11 years. 15
Results from the review demonstrated that males consume energy drinks more than females. Similarly, many studies reported that males are more likely to consume energy drinks than females.5,17–19 This might be attributed to the extensive marketing that promises to increase physical performance for males. Furthermore, Alsunni et al. explained the greater consumption of energy drinks among males in Saudi Arabia by the higher amount of physical activity males carry out compared to females. 10 Unlike the findings from these studies, Malinauskas et al. reported higher prevalence rate of consuming energy drink among female college students in the USA. 20 This might be due to the tactics followed by the energy drink companies such as using attractive feminine names like “Go GIRL”, and introducing the sugar-free and diet versions to reduce the gap between gender in the consumption of energy drinks.
Estimated rates of energy drink consumption
Meta-analysis results showed that the estimated rate of energy drink consumption is 46.9% with I-square = 3.7%, and the estimated rates of energy drink consumption among school students tend to be higher (65.3%) than university students (29.3%). However, this finding could be limited by the sampling issues such as sample size and method followed in the reviewed studies. Using different cut-off points for defining the prevalence of energy drink use such as: (1) ever consumed energy drinks; (2) consumed energy drinks once in the past 12 months; (3) consumed energy drinks the previous month; (4) consumed energy drinks the previous week; and (5) consume the energy drinks on a daily basis also might lead to the vast variation in the findings.
Similar findings on the consumption rate of energy drinks among school students were reported in a study in Atlantic, Canada where 62% of 7th, 9th, 10th and 12th school students were found to have consumed energy drinks at least once in the previous year in 2012. 6 While findings on the consumption rate of energy drinks among university students reported from some studies carried out elsewhere20,21 are higher than the prevalence in this review.
The common use of energy drinks among school students is alarming, and calls for policy, preventive and research response in order to tackle this issue and ensure the safety of this population.
Patterns of energy drink use
Findings on the patterns of consuming energy drinks vary between the studies due to the differences occurring between regular users who consume energy drinks on a daily basis and irregular users who might use 1–2 or 2–3 cans per week/month/year. For instance, some researchers found that 4.6% of regular users of energy drinks consume them more than once daily and about 20.3% consumed them on a daily basis, while 15.2% used energy drinks 2–3 times per week. Worryingly, Musiger et al. reported higher frequency of energy drink consumption (>5 cans weekly) among 22% of schoolchildren aged from 12 to 19 years compared to 52% of college students with the average age of 21 who consume >1 can monthly. 7 A noteworthy finding by Alsunni et al. stated that 53 (39.5%) males and 9 (34.61%) females consume maximally two cans in a single day. 10 This calls for raising awareness among school and university students on the safe daily allowance for consuming energy drinks per day, and consequences of excessive consumption of energy drinks on health.
Awareness on the content and potential associated side effects
It was worrying that a large number of the included study sample in the review were not aware of the active ingredients, particularly caffeine, in the energy drinks. Even more worrisome, the majority of the adolescents who participated in the study carried out by Musiger et al. considered energy drinks to be soft drinks. 7 Similar results were found in a study carried out elsewhere, and 69.6% did not know the exact definition of energy drinks and their composition. 22 In addressing the issue of energy drinks with students, parents should play a role in educating their children on the content of energy drinks and potential associated side effects. In the school, sport teachers and schools’ nurses should take the responsibility of educating the students on the main ingredients of energy drinks, the safe daily allowance of energy drinks (500 ml or one can/per day), and the potential associated side effects. Coaches and athletic departments also should take the lead in educating athletes on the differences between sport and energy drinks and the main active ingredients used in energy drinks.
As a consequence of the adverse effects linked to the consumption of energy drinks in the USA, the American Academy of Pediatrics in 2011 recommended against energy drink intake among the young. 25 See Appendix 2 for the recommendations of the American Academy of Pediatrics. 26
Many factors are believed to increase caffeine overdose among youth including: inadequate labelling, massive marketing and advertising, and the ingestion of multiple cans daily as a result of the claim of enhancing performance: “more is better”. 27 Therefore, improving the labelling of the energy drink contents and regulating the marketing are needed.
Energy drink consumption and associated behavioural problems
Many studies focused on the possible association of energy drink consumption and several risky behaviours such as substance use and smoking. A positive association was found between frequent consumption of energy drinks and behavioural problems.3,6 Findings from this review for instance showed that smokers consume energy drinks more commonly than non-smokers. 9
More research in the Gulf Co-operation Council states should examine the association of energy drink consumption with risky behaviours such as smoking, substance use and mixing energy drinks with non-medical prescription drugs.
Reasons for energy drinks’ use
Several drives for using energy drinks have been identified from the reviewed studies. Taste and flavour of the energy drinks were commonly cited by school and university students to motivate the use of energy drinks. These subjects might be attracted by the taste of the high level of sugar that many energy drinks contain, also some brands use “diet-sweeteners”, which are preferred by some people. University students frequently mentioned using energy drinks to boost their energy for studying especially during exams, and to promote athletic performance. Similar findings were reported by many studies (e.g. Aslam et al. 22 ). Energy drinks are designed to boost the energy of users through using stimulants (mainly caffeine), vitamins and herbal supplements. Many studies associated the consumption of energy drinks with moderate improvement in physical endurance, alertness and psychomotor performance. 3 Unlike the findings by these studies, other studies did not find significant associations between energy drink consumption and physical or cognitive outcome.2,3 Although energy drinks are able to enhance physical endurance temporarily, prolonged and excessive use has many side effects on the health of the individuals. 22
Peer pressure was another common reason for purchasing energy drinks by school and university students. This finding is in line with findings from other studies that confirm the influence of peers on purchasing and consuming energy drinks. 27
Implications of this review
The results of this review suggest a number of recommendations that will further enhance the safety of energy drink consumption among people in the Gulf Co-operation Council states. These recommendations include the following:
Policy and enforcement might include28–30
Prohibiting advertising energy drinks through all media sources Prohibiting the promotion of energy drinks in campaigns, and prohibiting energy drink companies from sponsoring sport or social cultural events Prohibiting free distribution of energy drinks to consumers of all age groups Emphasising writing a label in Arabic language that contains:
^ The main ingredients ^ Health warning on the harmful effects associated with consuming more than the recommended daily allowance by adolescents (one can/day). ^ Special warnings on the consumption for pregnant and breastfeeding women, people with diabetes, hypertension and cardiovascular diseases, people with caffeine allergy and for people aged <16 years old. Banning the sale of energy drinks from corner shops, cafeterias, restaurants, public and private gyms Training peadiatricians and general practitioners on counselling and screening for energy drinks among children and young adults.
Public education might include
Motivating health care providers such as general practitioners and school nurses to counsel adolescents on the active contents of energy drinks and possible risks associated with consuming energy drinks. Carrying out educational campaigns designed to raise awareness among adolescents and young adults of energy drink contents and side effects associated with excessive consumption. Motivating sport coaches to raise awareness among the young of the contents of energy drinks, and possible associated side effects.
Research might include
Carrying out further systematic research among adolescents and young adults in the Gulf Co-operation Council states to assess awareness of the contents of energy drinks and associated side effects, and awareness of the safe daily allowance. Carrying out research that examines the relationship between energy drink consumption and other problem behaviours including substance use and mixing specific medications/alcohol with energy drinks.
Limitations of the review
The heterogeneity of the reviewed studies, and variable availability of sub-group data, was a major limitation in our review process. As a result, our outcomes are necessarily of only a generalised nature, and could not be given with measures of confidence. All of our reviewed studies were published in English. Nevertheless, this review has several important implications for policymakers and public health planners as discussed above. It provides evidence on the need to carry out educational campaigns in schools and universities to raise awareness of energy drinks' use and the health risks associated with their use.
Conclusion
Enhancing the safety of energy drink consumption among all subjects in society, especially the young, is essential, and to achieve this goal integrated efforts between different stakeholders should be ensured. The results of this review lead to several recommendations for policy and enforcement, public education and research that can help policy and decision-makers to achieve the goal of safer use of energy drinks.
Footnotes
Declarations
Acknowledgments
The authors thank Dr Amna Almarzouqi for inventing the idea of carrying out a review of energy drinks in the Gulf.
Provenance
Not commissioned; peer-reviewed by Dalia Dawoud
