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Health and Nutrition / Sports Medicine

What’s in Your Energy Drink?

Deconstructing the hype

Ken Leclerc | May 30, 2013

Energy drinks are beverages that are marketed to provide mental or physical energy or stimulation. There are dozens of these products available, including such recognizable names as Red Bull, 5-hour Energy, and Rockstar. These are typically classified as beverages rather than food supplements and are situated on the consumer food and beverage shelf beyond the control of the Food and Drug Administration.

Energy drinks are considered to be different than sports drinks such as Gatorade, Powerade, and Accelerade. Sports drinks are carbohydrate and electrolyte beverages designed to enhance endurance exercise performance. Sports drinks can also include protein-rich preparations such as Cytomax, EAS Lean, and Boost. Some athletes use these drinks to promote protein synthesis and muscle development.

Although energy drinks may have multiple ingredients ranging from a familiar grouping of B-vitamins and minerals to lesser-known substances such as taurine, citicoline, and malic acid, the sole ingredient that causes the desired stimulation is caffeine. This may be listed specifically as caffeine or indirectly as guarana or yerba mate, two substances that contain caffeine. The other ingredients typically found in energy drinks are not believed to be harmful; however they have little, if any, stimulatory effect.

As there is no legal obligation to do so, not all energy drink labels have caffeine listed as an ingredient. Even if listed, the actual quantity of caffeine may not be. According to a 2012 Consumer Reports investigation of energy drinks, caffeine levels per serving of the most popular energy drinks ranged from about 6 milligrams to 242 milligrams per serving (with some containers providing more than one serving). By comparison, an ordinary cup of coffee or tea may have 100–175 milligrams of caffeine, premium coffees can have 200–400 milligrams of caffeine, and colas may have only 25–50 milligrams.

At rest, energy drinks may well provide more alertness or attentiveness and rev up metabolism slightly, but their effect on exercise is less well known as these products have not been subjected to rigorous study under exercise conditions.

So the question of whether energy drinks are ergogenic (performance enhancing) really falls to research done on the effects of caffeine, which has been studied extensively. Caffeine has been proven to stimulate the central nervous system, alleviate fatigue, increase wakefulness, and improve concentration and focus.

There is some evidence that it also can improve performance; the American College of Sports Medicine reports that “caffeine ingestion of between 3 and 9 milligrams per kilogram of body weight prior to exercise increases performance during prolonged endurance exercise and short-term intense exercise lasting approximately 5 minutes in the laboratory.” Some athletes have also noted an increase in power and endurance when using caffeine and have looked to caffeine as a means of enhancing performance.

The exact mechanism is not entirely clear, but could involve the sparing of glycogen (stored glucose in muscles), or a stimulating effect on central neurologic control centers. Because the effective dose ranges are noted at 3–9 milligrams per kilogram of body weight, for a 70-kilogram (154-pound) individual, the ergogenic dose would be 210 to 630 milligrams, between one and three servings of a typical energy drink. Beyond the direct physical effects, individual athletes need to make a decision about whether consuming more than the usual amount of caffeine associated with typical beverage consumption constitutes any unethical advantage over others.

Side effects of excessive caffeine ingestion should be a concern. According to the Mayo Clinic, healthy adults who ingest 200-300 milligrams of caffeine per day—roughly the amount of caffeine found in two to four cups of coffee—usually experience no negative side effects. However mega-doses, in excess of 600 milligrams per day, can cause problems including insomnia, nervousness, restlessness, irritability, stomach upset, increased heart rate, and muscle tremors. The downsides to excessive caffeine consumption are many, and everyone from fitness swimmers to elite competitors should monitor their ingestion of this legal drug. 

Although caffeine is not a banned or limited substance according to the World Anti-Doping Agency, it is currently on the list of monitored substances and could be banned in the future pending further investigation. In addition, the FDA announced in April of this year that it will start investigating the safety of adding caffeine to foods not normally associated with caffeine, such as gum, chips, snacks, and candy, all of which are attractive to children and young adults.

Summary points regarding energy drinks and exercise:

  • Energy drinks are not regulated by government agencies so contents vary widely
  • The stimulating agent in energy drinks is caffeine, the quantity of which varies greatly from one beverage to another
  • Various other ingredients found in these drinks are not considered to be dangerous, although not all are well studied and excessive amounts of any substance, including vitamins and minerals, could be problematic in susceptible individuals (and you may not know if you are susceptible)
  • Caffeine, in any form, is legal, and can enhance endurance performance within the range outlined
  • High levels of caffeine can promote undesired side effects, which in some cases could be harmful, such as dehydration or irregular heart rhythms.
  • Excessive use of caffeine may raise ethical questions regarding its use in competition and promote misdirected use to gain unfair advantage
  • Energy drinks are not sports drinks, which are known to be helpful in maintaining hydration and reversing carbohydrate and electrolyte losses during exercise.

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About the Author—Ken Leclerc

Ken Leclerc swims for Masters of South Texas. He is a practicing cardiologist at San Antonio Military Medical Center and a member of the sports medicine network maintained by the USMS Sports Medicine and Science Committee. 

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