Energy drinks (ED) sales have increased at an alarming rate worldwide and adolescents are highly represented in purchase figures raising concerns in both the scientific and general public communities of what effects these products are having on their health (Breda, et al., 2014; Pennington, Johnson, Delaney, & Blankenship, 2010). This literature review will examine published articles that investigate the health risks and consequences related to ED consumption by the adolescent population. It will also draw factual information from New Zealand (NZ) legislation and government websites. The motivation for investigating this clinical issue will be revealed and will be followed by an explanation of how the research tool PECOT was used in the formulation of the search question, “How is the consumption of EDs impacting the health of adolescents?”.
The review will begin by defining the term ‘ED’ and examining the ingredients that go into this dietary supplement. Investigating the impact of ED consumption on adolescent health will begin with reviewing the sociological aspects from a structural perspective on the legal aspects of sales, labelling and marketing of EDs. It will then explore the acute and long term physiological and neurological impacts of ED consumption and reference evidence from self-reporting cross-sectional studies. Evidenced based and personal recommendations will provide educational guidance and inform health care providers, adolescents, parents and caregivers, schools and communities, of the negative health impacts that can result from ED consumption and interventions to deter adolescent consumption.
While on my mental health placement at Infant, Child and Adolescent Mental Health Services I noticed that amongst general questions around functional and nutritional assessment there was a specific question about the consumption of EDs. This provoked my curiosity as to the relevance of this question, what the implications of consuming EDs might be, and how ED consumption may be impacting on the health of this population.
Data collected from Youth’12, a national representative survey of 8500 NZ secondary school students about health and wellbeing, indicates the popularity of ED consumption among adolescents (Utter, Denny, Teevale, & Sheridan, 2018). 35 percent of students reported drinking an ED in the previous week with 12 percent having consumed four or more. This 12 percent of frequent consumers was highly represented by males, Maori and Pacific students, and those living with socio-economic deprivation (Utter et al., 2018). Based on the increase in global sales and consumption, and incidences of daily consumption, it can be assumed that NZ’s adolescent consumption rates will also have increased (Pennington et al., 2010; Utter et al., 2018). Adolescents are attracted to EDs for their perceived benefits, however are often unaware of the harmful effects that EDs potentiate (Rath, 2012).
The Institute of Environmental Science and Research Ltd (ESR) and the Ministry of Health (MOH) state an adverse effect level of caffeine exposure as 3mg/kg body weight per day (mg/kg bw/day) (as cited in Thomson & Schiess, 2010). ESR examined scenarios of NZ teenagers consuming one, two, three or four retail units of either EDs or energy shots obtainable in NZ. Estimates indicated that following the consumption of one retail unit (in addition to baseline dietary intake) approximately 40% of teenagers would exceed this adverse effect level (Thomson & Schiess, 2010).
Moyer (2008) describes PECOT as an acronym which defines the elements that are present in a well-formed clinical question (as cited in Whitehead (2013)). PECOT can be used to develop a clinical question for research study or to unscramble a research question into specific keywords for purposes of sourcing relevant studies and literature (Whitehead, 2013).
The following table outlines the key elements of PECOT. From this I conducted searches using the CINAHL, Cochrane Library, Nursing and Allied Health, ProQuest Central, PubMed Central for literature published between 2000-2018 using keywords that addressed associations between ED consumption and adverse health outcomes in adolescents. Initially I applied a geographic subset of NZ, however results were few due to the lack of local research, investigation and literature. I selected primary and secondary source articles which I judged to be most relevant. Articles that were funded by ED manufacturers were excluded from the results.
Information relating to the question
13 – 18 years.
· Erikson (1968) describes this psychosocial stage between childhood and adulthood as a period when adolescents seek a sense of identity through exploration and experimentation. This can sometimes involve risk-taking behaviours with the aim of ‘fitting in’.
· Caffeine has negative impacts on the growing adolescent body which is still developing physically, intellectually and emotionally (Rodgers, 2017).
Self-reports of the presence of adverse effects by adolescents that consume EDs.
· Due to minimal previous exposure typically, adolescents have a minimal pharmacological tolerance to caffeine and so are more vulnerable to caffeine intoxication (Finnegan, 2003).
· Predominantly cross-sectional studies using self-report measures. Notable absence of rigorous experiments due to ethical constraints (Visram, Cheetham, Riby, Crossley, & Lake, 2016).
Self-reports of the absence of adverse effects by adolescents who do not consume EDs.
· Nil caffeine exposure.
Health in adolescents impacted through consumption of EDs.
· Consumption of EDs has a negative impact on the health of adolescents.
· The MOH has a responsibility to provide clear information, evidence and rationale to NZers, that supports a firm recommendation against ED consumption in children and in adolescents.
· Review of the marketing, sales, and labelling regulations of EDs is required.
· Research is required to ascertain aspects such as patterns of ED consumption among adolescents to ensure appropriate education interventions (Visram et al, 2016).
Six-year period of adolescence.
· It is assumed that during this time that adolescents are under the control of a caregiver and school authorities.
An ED also known as an energy shot or energy supplement is a non-alcoholic beverage (usually carbonated) containing multiple ‘energy enhancing’ ingredients (Smith, Smith, Miners, McNeil, & Proudfoot, 2000). Ingredients include high levels of a stimulant (usually caffeine, a psychoactive drug), often large amounts of sugar, water soluble B vitamins (such as B12, thiamine and riboflavin), amino acids (such as taurine) and a combination of other ingredients including unknown quantities of guarana and ginseng (Breda, et al., 2014; Smith et al. 2000). The MOH and the World Health Organisation (WHO) do not recommend that children and young people consume EDs (Ministry of Health [MOH], 2012; World Health Organisation [WHO], 2014).
Currently over 40 different ED products and energy shots are available on the NZ market at various localities including supermarkets, service stations, independent outlets such as dairies, in four percent of NZ secondary schools as well as online retailers (Ministry of Health, 2016a; Thomson & Schiess, 2010). Retail units of EDs are often non-resalable containers ranging 250-600ml in size providing caffeine exposure of 75-240mg. Energy shot sizes range 30-120ml with caffeine exposures of 10-300mg per retail unit (Thomson & Schiess, 2010).
The Ministry for Primary Industries enforces the NZ (Australia NZ Food Standards Code) Food Standards 2002 which regulates the adding of caffeine to food and beverages and food labelling in NZ (Ministry for Primary Industries, 2018). This states that a formulated caffeinated beverage must contain a minimum of 145mg/L (36mg/250ml) and a maximum of 320mg/L (80mg/250ml) total caffeine. It prescribes that advisory statements including disclosure of caffeine content (mg/100ml and per serving size), ingredients and cautionary consumer advice such as not being recommended to children be included on the label (Food Standards Australia New Zealand, 2015).
In NZ, ED companies can classify their product as dietary supplements due to their containing multiple ‘energy enhancing’ ingredients. In doing so EDs become regulated by the Dietary Supplements Regulations 1985 formed under the Food Act 1981 (as cited in Smith et al. 2000). This means that the ED companies are not controlled by the above formulated caffeinated beverage regulations and have no obligation to disclose the caffeine content of guarana despite 1g of guarana containing 40-80mg of caffeine (Oddy & O'Sullivan, 2009; Seifert, Schaechter, Hershorin, & Lipshultz, 2011).
The focus of ED marketing is on the stimulant effect and apparent enhancement of physical performance, mental alertness, endurance and weight loss (Breda, et al., 2014). Manufacturers claim their products are not marketed to those aged under 18, however aggressive marketing is often through youth-oriented media, venues, digital media and sponsorship of extreme sports events (Pomeranz, Munsell, & Harris, 2013). International market research firm Mintel ascribes the success of these approaches to ED companies drawing upon adolescents’ yearning for rebellion, adventure seeking, risk-taking and popularity (Gallimberti, et al., 2013).
EDs are potentially hazardous to numerous aspects of adolescent health both acutely and chronically, i.e. with habitual consumption (Rath, 2012). Acute health risks associated with the consumption of EDs, are predominantly due to caffeine content (Breda, et al., 2014; Ibrahim & Iftikhar, 2014). Caffeine, an addictive substance is perhaps the world’s most frequently ingested, socially acceptable, pharmacologically active substance and is found in beverages such as coffee, tea and soft drinks, in cocoa containing products such as chocolate, and in some medications such as some pain remedies (Nawrot, et al., 2003). Caffeine is quickly absorbed following oral ingestion, achieves peak plasma concentration within 30-120 minutes and has an elimination half-life of three-six hours depending on multiple factors such as age, sex and concomitant consumption (Babu, Church, & Lewander, 2008). Exposure causes alterations to regular physiological processes by binding to cell membranes taking the place of the inhibitory neurotransmitter adenosine resulting in the release of norepinephrine, dopamine and serotonin in the brain, the surge of circulating catecholamines, and ultimately a stimulating effect (Fogger & McGuinness, 2011).
Caffeine provides many pharmacological and psychological effects. Beneficial effects include enhanced aerobic endurance and performance, elevated energy, alertness, motivation memory and attention span (Alsunni, 2015). Caffeine’s most significant effect is the powerful stimulus it has on the cardiovascular, gastrointestinal, peripheral and central nervous systems (CNS) by influencing the actions of neuronal control pathways (Hernandez-Huerta et al., 2017). Excessive CNS and cardiac stimulation can cause the following adverse effects: heart palpitations, dizziness, convulsions, tachycardia, hypertension, irritability, nervousness, anxiety, tremors, disturbed sleep, diuresis, metabolic acidosis, hypocalcaemia, an increase in body temperature and gastric secretions and irritation of the gastrointestinal tract causing stomach aches, diarrhoea, nausea, and vomiting (Gallimberti, et al., 2013; Pomeranz et al., 2013).
The neurological and cardiovascular system effects of caffeine impact negatively upon the rapidly growing adolescent body in particular upon the CNS which is in the final
stages of development (Breda, et al., 2014; Oddy & O'Sullivan, 2009). Adolescence is a period when good quality sleep and nutrition is important, and when this population group is
more sensitive to the adverse effects of EDs such as sleep disturbance, anxiety and increased blood glucose (Stasio, Curry, Wagener, & Glassman, 2011). Consumption of EDs potentiates a negative cycle of inadequate sleep, increased consumption of EDs and increased health concerns (Koivusilta, Kuoppamaki, & Rimpela, 2016). Adolescence is a critical period for bone mineralisation. Caffeine impacts negatively on calcium deposition in bone by hindering intestinal calcium absorption (Seifert, Schaechter, Hershorin, & Lipshultz, 2011). Adolescents are at risk of physical dependence and addiction (Breda, et al., 2014; Nawrot, et al., 2003). Caffeine withdrawal symptoms are variable and dependent on normal caffeine consumption however adolescents can experience headaches, fatigue, irritability, anxiety, and are poorly focused when abstaining from exposures as little as 50mg caffeine (Dews, O'Brien, & Bergman, 2002).
Additional potential negative health and behavioural outcomes associated with the consumption of EDs by adolescents include problems with cognitive capabilities and behaviour modification, sensation seeking, binge drinking, usage of tobacco and other harmful substances, an increased risk for depression, and injuries that necessitate medical treatment (Breda, et al., 2014). From analysis of the Youth ’12 survey, Utter et al., (2018) discovered an association with many indicators of mental health and emotional distress. Students who reported consuming four or more EDs in the previous week described more depressive symptoms, emotional difficulties and poorer levels of wellbeing than those who reported nil consumption of EDs. The practice of mixing EDs with alcohol has been associated with risky drinking behaviours and is of grave concern (Ibrahim & Iftikhar, 2014). When combined with alcohol the caffeine content of the ED reduces drowsiness allowing an individual to remain alert for extended drinking episodes, increasing the risk of caffeine overdose and alcohol intoxication (Breda, et al., 2014).
Throughout this literature review there was reoccurring international reference to the negative health effects experienced by adolescents following the consumption of EDs. Crane (2009) states that school nurses in the United States of America have seen an increase in students presenting in health clinics with physical complaints of jitteriness, nervousness, an inability to concentrate, gastrointestinal upset, dizziness and insomnia (as cited in Pennington et al., 2010). Healthcare providers report having seen accelerated heart rates, dehydration, acute mania and anxiety (Pennington et al., 2010). In one case a female was taken to hospital with complaints of palpitations and chest tightness. Observations included blood pressure of 120/55, heart rate of 219 bpm, and an electrocardiogram showing a narrow complex tachycardia. Following an intravenous bolus of adenosine, she converted to normal sinus rhythm (Pennington et al., 2010). Teachers have referred students to the school nurse after observing physical effects in students, complaining that students experiencing the effects of ED consumption are more disruptive and less focused (Pennington et al., 2010).
Although long term health risks of habitual ED consumption are not entirely known there is an assumption these would include increased risk of obesity, diabetes, dental erosion, dental cavities, heart disease and stroke. The increased risk of these would be due to the high sugar content, caffeine’s effect in reducing insulin sensitivity, low pH content, and high levels of sodium found in EDs (Breda, et al., 2014; Pomeranz et al., 2013). The unknown acute and long term health impacts from the combination of the other specialty ingredients that are found in EDs, some of which are also found in non-prescription diet drugs, raises further concerns for consumers, especially youth who have habitual consumption (Breda, et al., 2014; Pomeranz et al., 2013).
Findings from this literature review indicate the need for interventions to inform adolescents of the side effects and possible health risks from drinking EDs and ultimately prevent consumption. (Gallimberti, et al., 2013; Pennington et al., 2010).
Through the NZ Health Strategy 2016 (NZHS), the MOH recognises the important role that NZ’s health system plays in providing NZers with the information to be self-managing in their health care and health choices (MOH, 2016b). The ‘life course approach’ that recognises the wider context, this being the connection between health and factors external to the health system such as dietary behaviours, is also acknowledged (MOH, 2016b). Improving health literacy requires service providers to work in partnership with health consumers, to inform, empower, support, and encourage them to make informed smart health choices (MOH, 2016b). The MOH does not recommend that children consume EDs (MOH, 2012). However, there appears to be a lack of information and commitment in addressing the issue that is apparent. The MOH has a responsibility to provide clear information, evidence and rationale to NZers, that supports a firm recommendation against ED consumption in children and in adolescents.
At community level, measures to improve public awareness of the side effects and potential health risks associated with the consumption of EDs is required (Ibrahim & Iftikhar, 2014). The NZHS states that the MOH has a focus on preventing illness and making health choices easy by providing the NZ population with health information and initiatives (MOH, 2016b). Education around the dangers of ED consumption to communities could be in the form of a general public meeting delivered by primary health care providers such as public health nurses.
At clinical level, health care providers, in particular public health nurses need to be informed and equipped to educate families and adolescents about the dangerous consequences of excessive consumption of EDs, the signs of caffeine intoxication, withdrawal symptoms, and dependency (Breda, et al., 2014; Pennington et al., 2010). Primary health care providers should screen for ED consumption on every contact with adolescents (particularly males) especially when seeing someone for diet or substance use related presentations to identify those at risk of caffeine toxicity (Breda, et al., 2014; Ibrahim & Iftikhar, 2014; Oddy & O'Sullivan, 2009). Consumption inquiry should seek to identify the quantity, volume, frequency and type of retail units consumed, and drink mixing habits (Ibrahim & Iftikhar, 2014).
Educational initiatives such as newsletter advice and health promotion evenings that target parents and students could be co-ordinated by school authorities or public health nurses (Pennington et al., 2010). Through education and encouragement, parents will be empowered to limit accessibility of EDs, and be more attentive to what their adolescents are consuming (Magnezi, Bergman, Grinvald-Fogel, & Cohen, 2015).
The awareness of the harm caused by EDs serves as a protective factor against adolescents consuming EDs (Gallimberti, et al., 2013). Therefore, education and improved label information could be effective in discouraging consumption (Pomeranz et al., 2013). Information to inform choice would include a comprehensive list of ingredients, total caffeine content, a warning of potential harm to health, a recommendation for ‘occasional use only’ and reference to the MOH’s advice against consumption by those aged under 18 (Gallimberti, et al., 2013; Pomeranz et al., 2013).
The Advertising Standards Authority forbid the marketing of EDs to those aged under 18, however with no regulation in place for the sale to minors i.e. no age restriction for the purchase of these supplements, anyone of any age can purchase EDs (Advertising Standards Authority, 2018). Due to the detrimental developmental and adverse health effects that caffeine potentiates on the growing and developing adolescent body, there needs to be serious consideration of prohibiting the sale of EDs to those younger than 18 years (Breda, et al., 2014). This should begin with an immediate ban of ED sales in the secondary school setting, and definite ban on ED brand sponsorship at/of events attended by those under the age of 18 years (Pomeranz et al., 2013).
Retail regulations similar to those that control the sale of tobacco and alcohol for example in-store location of product should be considered. Currently EDs are often located in refrigerators aside non-alcoholic sugary beverages/mixers and in licenced premises alongside alcoholic beverages (Pomeranz et al., 2013). Firstly, this type of display implies that EDs are in the same category as soft drinks/mixers and secondly that they are a suitable option for mixing with alcohol (Pomeranz et al., 2013). Placing EDs behind the counter would limit accessibility and insinuate their usage status as being restricted. Other interventions may include banning two for one offers, reducing the size of a retail unit, restricting packaging to bottles only, and restricting the maximum amount of caffeine per unit (WHO, 2014).
Further comprehensive research on ED consumption among NZ adolescents is necessary to determine the actual risk to health, and would include various areas of investigation such as:
(Breda, et al., 2014; Ibrahim & Iftikhar, 2014; Oddy & O'Sullivan, 2009; Thomson & Schiess, 2010).
This review contributes to the expanding evidence base on the negative impacts on adolescent health associated with ED consumption. ED consumption among the adolescent
population is of concern due to the health risks particularly those associated with excessive consumption of caffeine (Breda, et al., 2014; Ibrahim & Iftikhar, 2014).
Adolescents who consume EDs are vulnerable to a wide range of negative health outcomes including caffeine toxicity, disturbed sleep, cardiac abnormalities and mood disturbances (Utter et al., 2018). Preventative interventions are necessary to address this multi-dimensional public health problem and require cross-agency collaboration (Holubcikova, Kolarcik, Madarasova , Reijneveld, & van Dijk, 2017). At a structural level improved legislation around sales regulations, marketing and labelling is necessary to protect adolescents against the health risks associated with ED consumption (Breda, et al., 2014).
Health care providers must be aware of ED consumption consequences including the signs of caffeine intoxication, withdrawal symptoms and dependency, and be ready to deliver appropriate education to families and adolescents (Rath, 2012). Screening for ED consumption when seeing an adolescent will identify those at risk of caffeine toxicity and adverse health effects (Oddy & O'Sullivan, 2009). Secondary schools can provide health education and initiatives to discourage ED consumption by not selling EDs or allowing ED consumption on school grounds (Pennington et al., 2010). Further research around understanding the patterns and motives for ED consumption will assist in implementing appropriate inventions and provide an improved understanding about the impact that EDs are having on the health of adolescents (Visram et al, 2016).
Raeleen Thompson, Senior Lecturer, School of Nursing, Otago Polytechnic, for her encouragement and support, and advice on refining my recommendations.
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