It’s hard not to notice the flood of stories about energy drinks in the media these days. Energy drinks have become popular with both teens and adults alike because of their claim to increase stamina and mental and athletic performance. However, despite their popularity and the lower-calorie alternatives that are available, a number of questions have been raised pertaining to energy drinks’ appeal to the younger crowd and their caloric and caffeine content. In addition, there have been anecdotal reports of increases in emergency room visits due to excessive caffeine intake and, among other young adults, combining energy drinks with alcohol. Although the energy drink beverage category is seemingly gaining momentum, there is little research to understand consumption patterns and potential health effects. The conflicting stories have people wondering: What’s the real deal with energy drinks?
Energy drinks are the fastest growing beverage category in the United States. Between June 2006 and June 2007, U.S. consumers spent $744 million on them, a 34 percent increase over the previous year (Consumer Reports, 2007). First introduced in 1997, their popularity is visible in the wide array of energy drink offerings on store shelves and the attention they garner with the news media. Energy drinks typically contain higher levels of caffeine than soda, and also may contain glucose, guarana (a natural source of caffeine) and taurine, all of which have also been associated with a perception of increased energy.
Caffeine has been consumed for thousands of years in foods and beverages such as coffee, tea, and chocolate. The U.S. Food and Drug Administration (FDA) has classified caffeine as Generally Recognized As Safe (GRAS), and the American Medical Association (AMA) holds the position that "Moderate tea or coffee drinkers probably need have no concern for their health relative to their caffeine consumption provided other lifestyle habits (diet, alcohol consumption) are moderate as well." Most experts consider moderate caffeine consumption to be about 300 mg, or about three cups of coffee per day for all populations, including sensitive subpopulations such as pregnant women (IFIC Foundation’s IFIC Review—Caffeine and Health: Clarifying the Controversies, 2007).
A study in the Journal of Analytical Toxicology (2006) found that when ten different brands of energy drinks were tested, caffeine levels ranged from 0-141 mg/serving. In comparison, an average eight-ounce cup of brewed coffee contains 65 to 120 mg of caffeine, tea has 20 to 90 mg, and caffeinated soft drinks have 20 to 40 mg per serving. A person wishing to consume a moderate amount of caffeine would need to take into account the amount of caffeine consumed from all sources to stay within a range of 300 mg per day.
Caffeine has been shown to have benefits related to physical and mental performance. Some studies using energy drinks have shown that energy drinks can improve or maintain mood and performance during tedious and mentally demanding tasks. One study (Amino Acids, 2000) in particular measured how a drink containing taurine and caffeine affected human mental performance and mood. The study tested motor reaction times in response to hearing a specific tone. The group that did not consume the energy drink had significantly longer reaction times at the end of the study, whereas the group that had consumed the energy drink mixture maintained their reaction times. Similarly, the participants were asked to complete the Basler Psychological Balance questionnaire, a common measure of well-being, both before and after the study. The non-energy drink group reported reduced feelings of well-being, vitality and social exuberance at the end of the study, whereas the energy drink group maintained their feelings of well-being. The study was split between habitual caffeine drinkers and non-caffeine drinkers to ensure that symptoms sometimes felt from the absence of caffeine were not causing the decline.
Improved performance in situations that cause fatigue is generally the aspect of caffeine-containing drinks that consumers (such as college students looking to stay awake to study for a big test) seek. However, consuming energy drinks, coffee, or other caffeinated beverages as a substitution for sleep will eventually lead to sleep deprivation, which can have undesirable effects. Consuming very high levels of caffeine has also been associated with increased heart rate, nausea, restlessness, anxiety, and tremors. Caffeine consumption levels that lead to these symptoms vary for each individual; however, moderate caffeine intake has not been shown to cause these effects in the normal, healthy population.
Individual sensitivity to caffeine varies, so consumers who are concerned should calculate their intake. Caffeine must be listed as an ingredient on the product label, and although labeling the amount of caffeine is not mandatory, many manufacturers of caffeine-containing beverages, including energy drinks, voluntarily include this information. If the caffeine content is not included on the label, it may be obtained by visiting the company Web site or calling the company’s customer service line. Not all energy drinks contain the same amount of caffeine, so the amount in one cannot be estimated based on another. Certain subpopulations such as pregnant women and children should monitor their caffeine intake and consult their physician regarding their own personal consumption levels.
In addition to questions related to caffeine, the popularity of energy drinks with children and teens has parents concerned about possible contributions to childhood obesity, due to potential consumption of excess calories. Some energy drinks may contain 200 or more calories per serving, which, as with other high-calorie foods and drinks, may cause weight gain, especially when consumed in amounts that exceed the daily need. While there is considerable debate on the contribution of high-calorie drinks to the burgeoning problem of overweight with children and adults, it is clear that management of overall daily caloric intake is one way to avoid excess weight gain. Consumption of energy drinks should be moderated, as with any other food or beverage, to ensure appropriate overall calorie and micronutrient intake.
There have been several studies on caffeine’s effects on metabolism and weight change. In a study in the American Journal of Clinical Nutrition (1980), caffeine and caffeinated coffee significantly increased metabolic rate during the three hours after ingestion. Lipid oxidation was also shown to increase in subjects performing exercise after caffeine ingestion. The study therefore concluded that the consumption of caffeine or coffee, in reasonable amounts, would be a supplementary advantage to those following a weight reduction regime. However, using caffeine as a weight loss tool is generally not recommended.
At this relatively early stage of energy drinks in the marketplace, more research is needed to determine their long-term effects on health and obesity. Based on current research, energy drinks have been shown to improve performance and mood due to their caffeine content. As with all sources of caffeine and calories, moderate intake should be emphasized.
