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Energy Drinks: What Teenagers (and Their Doctors) Should Know

2013; American Academy of Pediatrics; Volume: 34; Issue: 2 Linguagem: Inglês

10.1542/pir.34-2-55

1529-7233

Kwabena L. Blankson, Alastair M. Thompson, Dale Ahrendt, Vijayalakshmy Patrick,

Obesity, Physical Activity, Diet

Hundreds of different energy drinks are available and are marketed to adolescents, carrying the potential for substance abuse that involves caffeine and alcohol. Clinicians must be educated to deal with their patients' use of these products.After reading this article, readers should be able to:Energy drinks are caffeinated beverages advertised as boosting the immune system, enhancing performance, and creating a "buzz" or a "high." Some of these drinks contain alcohol, and sometimes consumers mix them with alcoholic beverages. This article reviews current information about the content, benefits, and risks of the use of these energy drinks by adolescents.Adolescents are no strangers to energy drinks, and over the past 2 years, media reports have heightened the awareness of doctors, parents, and lawmakers. In 2010, nine university students in Washington State were hospitalized and one almost died; their illness was attributed to a fruit-flavored, caffeinated alcoholic drink. A month earlier, on a college campus in New Jersey, 23 students were hospitalized after becoming intoxicated, again reportedly after drinking the same product. Both campuses have since banned this caffeinated alcoholic beverage.Shortly thereafter, Washington State Attorney General Rob McKenna reflected, "It's time to bring an end to the sale of alcoholic energy drinks. They're marketed to kids by using fruit flavors that mask the taste of alcohol, and they have such high levels of stimulants that people have no idea how inebriated they really are." The Food and Drug Administration (FDA) has issued a strong warning to at least one manufacturer about safety concerns when alcohol and caffeine are combined in a product. Banning caffeinated alcoholic drinks would be an important first step, but it may do little to curb the practice of mixing energy drinks and alcohol, a fixture of the college (and most likely high school) party scene. The dangers of alcohol use in adolescence are well described in the medical literature, but the safety of energy drinks is a subject under much debate and the focus of this review.Energy drinks were first introduced in the late 1980s. Presently, the energy drink market brings in upward of $5 billion a year, with >200 new brands introduced into the United States market in 2006. The market's leading drink accounted for almost 49% of the revenue.The US energy drink market has grown to its current size by being focused predominantly on adolescents. One leading market research company found that teens increased their energy drink consumption by 16% from 2003 to 2008, with 35% of teenagers regularly consuming energy drinks. In one study of energy drink consumption among college students, 50% consumed at least one to four drinks per month. (1) Reasons for drinking included inadequate amount of sleep, need for energy, and wanting to mix with alcohol. Although one drink was sufficient to meet most needs, those who mixed with alcohol often consumed three or more energy drinks. Almost one in three reported weekly "jolt/crash" episodes, including headaches and palpitations. (1)Energy drinks are marketed to adolescents, specifically males. Energy drink manufacturers allocate a significant amount of marketing resources to sports sponsorships, which include soccer teams, automobile racing teams, and extreme sports athletes. In a survey of almost 800 college students, 39% drank energy drinks in the past month (males more than females), and "jock identity" was associated positively with frequency of energy drink (and energy drink mixed with alcohol) consumption. (2)(3)Over the 3-year period spanning 2007–2009, although Americans were huge consumers of energy drinks, the energy drink market penetration held flat at 15% of all adults aged 18 and older. Energy drink nonusers cited high prices (48%), too much caffeine (43%), and a general feeling that energy drinks just are not good for them (43%) as reasons why they had not consumed any in the past 3 months.This attitude is forcing the energy drink manufacturers to come up with new strategies, such as targeting women, herb and vitamin enthusiasts, the affluent, and youth. (4) Energy drinks showing a "low, no, or reduced" calorie claim have increased from 6% to 11% between 2004 and 2008. Major soft drink manufacturers have begun injecting their own "energy drinks" into the market or are becoming distributors, further blurring the lines between regular carbonated soda and caffeinated energy drinks.Most energy drinks contain the same basic ingredients: guarana, taurine, ginseng, sugars, and B vitamins (ie, riboflavin, pyridoxine). Caffeine rarely is listed as an official ingredient, although all of the top-selling energy drinks contain caffeine. Many of them do not state the quantities of caffeine or other ingredients, shielding this information under the tag "proprietary blend." When caffeine content is stated, often the amount given is not accurate. The FDA regulates the amount of caffeine in cola beverages. Energy drinks and cold coffee beverages do not fall under the same jurisdiction. One of the reasons is that caffeine is a substance generally recognized as safe by the FDA, even though the FDA does regulate the sale of over-the-counter caffeine-containing drugs, one of which contains 100 to 200 mg of caffeine.A 6.5-oz cup of coffee, depending on how it is brewed, contains 80 to 120 mg of caffeine. A cup of tea contains approximately 50 mg of caffeine. And a 12-oz cola beverage by law cannot contain more than 65 mg of caffeine. Even the carbonated fountain sodas sold at fast-food establishments and gas stations contain less than 49 mg of caffeine per 16-oz serving. (5)The Table names some top-selling energy drinks, pointing out the volume in each.The caffeine in 16 oz of leading energy drink brands ranges from 154 to 280 mg (the equivalent of two to three cups of coffee). Some energy drinks contain 500 mg or more in a single can. Some of the drinks contain other stimulants, such as guarana, or additives that can enhance the effects of caffeine. Several Internet sites provide specific information about caffeine content.There is not a recommended daily allowance for caffeine, but the American Dietetic Association posits that women of reproductive age and children should consume no more than 300 mg of caffeine per day (two to three cups of coffee). (5) Caffeine use and withdrawal have been linked to a variety of health effects, including irritability, anxiety, mental confusion, hand and limb tremor, osteoporosis, digestive problems, nausea, insomnia and sleepiness, urinary frequency, headache, palpitations, arrhythmias, and elevated blood pressure. (6)Associations have been shown between caffeine consumption and premature birth, miscarriage, fetal growth retardation, and decreased birthweight. Withdrawal symptoms have been reported in school-age children who drank as little as 120 to 145 mg per day (one to two cups of coffee or three to five sodas) over a 2-week period. (7)Cardiovascular effects as a result of heavy caffeine use can be a significant source of morbidity in athletes. Hypertension and palpitations in the adolescent athlete often lead to extensive medical evaluations. The diuretic effect of high levels of caffeine could lead to dehydration in athletes who do not drink enough fluids to compensate.Although the World Anti-Doping Agency (WADA) removed caffeine from its list of banned substances in 2004, it is reconsidering its ban on caffeine given a recent adverse outcome in an Australian football league athlete. Athletes in the league routinely take as many as six caffeine tablets as a game-day stimulant, and then take a sleeping pill to "come down." A star player in the league was rushed to the hospital with complications following ingestion of this pill cocktail. Although WADA has not officially banned it for Olympic athletes, caffeine is well-recognized as an ergogenic aid or a performance enhancer, (8) and it remains on WADA's closely monitored drug list.The National Collegiate Athletic Association considers caffeine illegal if found in quantities in the urine that approximate five to eight cups of coffee consumed in 1 hour. Depending on the brand, that is the equivalent of as few as one to three energy drinks.Caffeine usage patterns have been studied not only in adolescent athletes, but also in the general teenage population. One study of high school students revealed that 95% consumed caffeine, most of it coming from sodas. Their first consumption of the day was in the evening. Those who drank more coffee expected dependence symptoms and energy enhancement from caffeine and also reported more daytime sleepiness and use of caffeine to get through the day. (9)Studies of depressed youth show that they use more caffeine than nondepressed youth, and caffeine likely exacerbates daily anxiety. (10) In another study, daily caffeine use was associated with dependence in some adolescents. The teens actually met Diagnostic and Statistical Manual – IV criteria for dependence because they experienced tolerance, withdrawal, persistent desire, or unsuccessful efforts to control use, and reported drinking caffeine despite physical or psychological problems associated with caffeine use. The caffeine intake in these daily users was only two to three cups of coffee. (6)In this same study, adolescents who met criteria for marijuana dependence (or any other drug abuse or dependence) consumed significantly more caffeine than those not dependent on marijuana or other drugs. Young adolescents are at risk; a survey of over 5,000 seventh graders showed that those possessing high caffeine risk (ie, consuming more than six cups of coffee in the previous month) were more likely to use tobacco or alcohol by 1-year follow-up. (6)With alcohol use, the intensity of response diminishes with repeated administration, leading to tolerance. Higher doses of alcohol may be needed to attain the initial effect, planting the seeds of abuse and dependence. Caffeine may work in the same fashion, and there is evidence that combining alcohol and caffeine increases alcohol tolerance in comparison with exposures to either drug alone, which is sobering evidence, given observations of adolescents mixing energy drinks with alcohol. (11)Guarana, also known as Brazilian cocoa, is a South American plant that is commonly added to energy drinks. It contains a substance called guaranine, which is caffeine, with 1 g of guarana being equivalent to as much as 40 mg of caffeine. (12) Of note, when an energy drink lists its caffeine content, it is usually not taking into account the guarana, which has been reported to exert a more prolonged effect than an equivalent amount of caffeine. In reality, when a drink is said to contain caffeine plus guarana, it contains caffeine plus more caffeine. Guarana has not been evaluated by the FDA for safety, effectiveness, or purity. All potential risks and advantages of guarana may not be known.Most energy drinks contain sugars in the form of sucrose, glucose, or high fructose corn syrup, with the sugar content varying from 21 to 34 g per 8 oz. Some adult studies have shown that glucose combined with caffeine can synergistically enhance athletic and cognitive performance. (13)(14) One study showed that one specific drink improved performance in a range of mental and physical measures. (15)The amount of glucose in energy drinks is similar to that found in sodas and fruit drinks. Users who consume two to three energy drinks could be taking in 120 to 180 mg of sugar, which is 4 to 6 times the maximum recommended daily intake, according to US Department of Agriculture dietary guidelines. Adolescents who consume energy drinks in abundance may be at risk for obesity and dental health problems as a result of high sugar intake.Taurine is one of the most abundant amino acids in the human body, and it is one of the most common ingredients in energy drinks. The human body can manufacture taurine on its own from other amino acids, although infants and sick adults must get it from their diet or supplements. Taurine is present in meat, seafood, and milk, and is purported to have beneficial physiologic effects. Most of these effects cannot be attributed to taurine alone, because it was mixed with caffeine and other substances.The amount of taurine consumed by regular intake of energy drinks far exceeds the amount in a normal diet (40–400 mg/day), although there is limited evidence of adverse events from taurine use. (12) Some data from animal models suggest that taurine might minimize some of the adverse effects of alcohol consumption and could, by extension, encourage greater alcohol consumption. (16)Ginseng is a root most commonly found in East Asia. It has been claimed that ginseng improves athletic performance, stimulates the immune system, and improves mood. Ginseng has been linked to adverse events such as insomnia, palpitations, tachycardia, hypertension, edema, headache, vertigo, mania, and estrogen-like effects, such as breast tenderness and amenorrhea. Many energy drinks do not contain therapeutic doses of ginseng (100–200 mg/day), with a user needing to drink two to four cans of an energy drink to get even the lowest therapeutic dose. (17) There is little scientific evidence that ginseng improves physical performance significantly.A host of other additives (eg, B vitamins, glucuronolactone, Yohimbe, carnitine, and bitter orange) purport to have a bevy of positive effects on consumers. Most of the claims about these ingredients, such as that they reduce cancer risk, improve sexual performance, and prevent diabetes, lack sufficient scientific evidence. The quantities of these ingredients found in energy drinks often are sub- or supratherapeutic, with doses so low or so high that no one knows what effect they have on the human body. Even taking into account some of the known physiologic benefits, little is known about the effects of daily consumption of energy drinks on long-term health.In a recent survey of ten universities in North Carolina, one-fourth of college students had consumed energy drinks mixed with alcohol in the past month. (4) These students were more likely to be younger, white, male, engaged in athletics, or members of fraternities or sororities. Those who consumed alcohol mixed with energy drinks (in comparison with those who consumed alcohol alone) had a significantly higher prevalence of alcohol-related consequences including:Another study of college students showed that energy drink users (in comparison with nonusers) had heavier alcohol consumption patterns and were more likely to have used other drugs (such as marijuana and prescription drugs), both concurrently and in the year preceding assessment. (18)From the bold, colorful cans, to the edgy names, energy drinks are marketed in a language teenagers know well. Sales messaging for a popular energy drink includes references to "house parties" and "jungle juice," the latter being a term for various improvised alcoholic beverages; both allusions have strong associations with underage binge drinking.Some of the most popular energy drinks are manufactured already mixed with alcohol. These alcohol-containing energy drinks share close resemblance to their non–alcohol-containing counterparts. And, in most cases, the alcohol-containing spinoff is less expensive. Energy drink manufacturers may be blurring the lines between their drinks and alcoholic beverages, and the teenage consumer might experience brand confusion.How much alcohol is in an alcohol-containing energy drink? The alcohol by volume (ABV) determination is one measure of the amount of alcohol in a beverage. The ABV content of one 23.5-oz can of a popular alcohol-containing energy drink is 12%. The ABV content of a domestic 12-oz beer ranges from 4.2% to 5%. The ABV of a standard wine bottle is approximately 12%.The strength of an alcoholic beverage is best understood in terms of units of alcohol, when ABV and the volume of the drink are known. One unit of alcohol is the amount of alcohol that an average healthy adult can metabolize in 1 hour. A unit of alcohol can be calculated with a simple formula:The number of units of alcohol in different alcoholic beverages is as follows:In the case of one popular alcohol-containing energy drink, the determination of units of alcohol is as follows: (12% ABV/1,000) × 695 mL (∼23.5 oz) = 8.3 units. Thus, a can of this drink has essentially the same strength as an entire bottle of wine (9 units); with its estimated 500 mg of caffeine, consuming it is comparable to drinking almost a 6-pack of beer plus five cups of coffee. Other 23.5-oz caffeinated alcoholic beverages range between 6.5% ABV and 12% ABV. Thus, drinking two to three of these drinks at a party could amount to drinking two to three bottles of wine/6 packs of beer, and 10 to 15 cups of coffee.Mixing these caffeinated alcoholic beverages with additional alcohol, as was done by the nine college students in Washington State, could be especially dangerous, given their already high alcohol content. This practice demonstrates either a poor understanding of the amount of alcohol in the mixed beverage or a disregard of the danger altogether.Adolescents who combine energy drinks with alcohol perceive less of an effect from alcohol. (19)(20) For example, one study noted that young adults who consumed energy drinks with alcohol felt fewer symptoms such as headache, weakness, and impaired muscular coordination. (19) But these participants still were impaired in terms of motor coordination and visual reaction time. The study by O'Brien reported that 15% of adolescents mixed energy drinks with alcohol "to drink more and not feel as drunk," and 5% of teens "did not want to look as drunk." (4)Thus, there is the grave danger that adolescents may feel unimpaired, when they are just as impaired as a person with the same blood alcohol level, and subsequently may drink much more than they intended to and attempt to drive themselves and others home. One high-potency drink might provide the rush of five cups of coffee; but the sobering reality is that the adolescent is now, as one school official stated, "a wide-awake drunk."What can the medical provider do? First and foremost, as with any other sensitive issue in the adolescent patient, the clinician must ask in the first place whether energy drinks are being consumed. How the question is asked is equally important. "You don't drink energy drinks, do you?" may not facilitate open discussion with the teenage patient.The HEEADSSS interview (Home, Education, Eating, Activities, Drugs/Alcohol abuse, Sexual activity, Safety, Suicide/Depression) provides an easy method and effective tool for examining the important spheres of adolescence that affect health and well-being. (21) Under the E, many clinicians address education, eating, and exercise, with sleep going hand-in-hand with these issues.During this interview would also be a perfect time to ask about energy drink use, either to stay up late to study, to get going in the morning, or to enhance athletic performance. Under the D, providers should ask about drug use, caffeine intake, and energy drinks, because studies have shown a connection between heavy caffeine use and illicit substance use. The interviewer also can ask about alcohol use, segueing into specific questions on alcohol mixed with energy drinks, based on a positive response. An opportunity for education might present itself; we suspect many teens will have no idea how much alcohol and caffeine they are consuming when they ingest these energy drinks.The CRAFFT pneumonic has been validated as an appropriate screening tool for substance abuse in adolescents. (22) It is a series of six questions developed to screen adolescents for high-risk alcohol and other drug use disorders. Have you ever ridden in a CAR driven by yourself or someone who had been using alcohol or drugs? Do you ever use alcohol/drugs to RELAX, feel better about yourself, or fit in? Do you ever use alcohol/drugs while you are ALONE? Do you ever FORGET things you did while using alcohol/drugs? Do your family or FRIENDS ever tell you that you should cut down on your drinking/drug use? Have you gotten into TROUBLE while you were using alcohol/drugs? Adding energy drinks mixed with alcohol to the questioning could be useful.College student drinkers who report mixing alcohol with energy drinks are at increased risk for alcohol-related consequences. Of great concern, students who report consuming energy drinks mixed with alcohol were more than twice as likely to ride in a car with an intoxicated driver. (4) Because teenagers who consume alcohol mixed with energy drinks underestimate their degree of intoxication, it is critical to educate all teens properly, as both drivers and passengers. If the person driving a teenager home says he is sober but has been drinking alcohol mixed with energy drinks, the teen passenger can assume the driver may be gauging his level of sobriety inaccurately.Clinicians should not be shy about bringing up this issue with their teenage patients. As with discussing sexuality, there is little proof that talking about the issue will encourage dangerous activity or behavior. Rather, education should be protective. Teenagers already know about mixing energy drinks with alcohol; adults (and specifically primary care providers) need more education. Some college students, in the wake of the ban of a popular alcohol-mixed energy drink, proceeded to stock up, while others posted web videos about how to manufacture a homemade version of the same drink, using hard candy, malt liquor, and energy drink. In addition, there is a popular website describing over 200 alcoholic beverages that call for energy drinks as an ingredient.Clinicians can apply the concepts of motivational interviewing in their discussions of energy drink consumption. A discussion of motivational interviewing with video can be found in Pediatrics in Review (Barnes AJ, Gold MA. Promoting Healthy Behaviors in Pediatrics: Motivational Interviewing. Pediatr Rev. 2012;33(9):e57–e68). [www.pedsinreview.org/content/33/9/e57.full].Pediatricians should discuss energy drink consumption with their adolescent patients. (23) Evidence suggests that energy drinks may provide some therapeutic benefit (increased wakefulness, focus, performance-enhanced exercise). But given the unknown levels of caffeine and other poorly studied additives, there is significant risk associated with energy drink consumption that may outweigh the benefits in the adolescent consumer.Energy drinks contain high, unregulated amounts of caffeine that may lead to significant morbidity in adolescents (cardiovascular effects, withdrawal symptoms, mixing with alcohol, association with substance dependence). Additives such as guarana, ginseng, taurine, carnitine, and bitter orange are not regulated by the FDA, and their short- and long-term side effects are incompletely understood.Little is known about potential negative interactions between energy drinks and common medications taken by adolescents, such as stimulants, antidepressants, and atypical antipsychotics, and there are case reports of energy drink consumption associated with new-onset seizures and manic episodes. (17) When mixed with alcohol, energy drinks present serious potential for harm and abuse. In-office counseling on daily exercise, early bedtime, and healthy dieting appropriately addresses some of the goals that underlie the reasons why adolescents choose to consume energy drinks.Primary care clinicians should be aware that abnormal vital signs (tachycardia, hypertension), insomnia, anxiety, palpitations, and headache are all potential effects of energy drink consumption. By educating themselves, adolescents, and parents about the potentially dangerous consequences of energy drink consumption, pediatricians may prevent unnecessary evaluation of symptoms due to energy drink effects and halt the needless hospitalization of young adults who mix energy drinks with alcohol.