Energy Drinks

[icon name=”user” class=”” unprefixed_class=””]  Joanne P. Shelby-Klein BSN RN

Energy drinks, most of us have seen them for sale in stores or advertised on television and sporting events. They are in common use, especially among teenagers and young adults and they make up a multi-billion dollar industry in the United States alone. The increasing usage of these beverages is a growing public health problem and healthcare providers are concerned that there are few regulations overseeing the contents of the energy drinks. What are energy drinks and what can they do to the body?


Energy drinks are marketed as a stimulant for both mental and physical activities. These drinks are usually fortified or enhanced with dietary supplements. Coffee, tea and soft drinks are not considered to be energy drinks even though they contain caffeine. The difference is that energy drinks container higher amounts of caffeine, sugars and other supplements. The manufacturers of energy drinks claim they contain natural ingredients and supplements that produce increased energy, concentration, attention spans and sports performances. Energy drinks have been available since they first appeared in Austria in 1987. They first appeared in the United States in 1997. Soft drinks such as coca cola first appeared in 1904. Both soft drinks and energy drinks contain caffeine, with energy drinks containing more caffeine than regular soft drinks or coffee.

  • A 12 ounce cola contains 34- 54 mgs or 2.9-4.5 mg caffeine per ounce.
  • A 6 ounce cup of coffee contains 77-150 mg of caffeine or 12.8-25mg per ounce.
  • Energy Shots are 1-2 ounce drinks that contain more concentrated amount of caffeine that ranges from 100-350 mg or 90-171 mg per ounce.
  • Caffeine levels in energy drinks range from 50-505 mg of caffeine per serving or about 2.5-37.5 mg of caffeine per ounce.

Energy drinks also contain other substances that may unknowingly raise the caffeine levels because drink producers are not required to list the amount of caffeine in herbal supplements. Here is a list of the other ingredients contained in energy drinks.

  • Amino acids such as Taurine and L-Carnitine.
  • Carbohydrates and sugars
  • Glucuronolactone, a natural occurring substance that converts certain compounds to a more water soluble state. There has been very little research done on this substance.
  • B Vitamins
  • Herbs such as ginseng, guarana, yerba mate, acai, cocoa, kola nut. These herbs may contain the unknown and unlisted caffeine levels.


Since first hitting the market in 1987, the use of energy drinks and shots increases annually in spite of the fact that there is no strong researched based evidence to support their use. People of any age use energy drinks, but the most prevalent usage is among adolescents, college students and young adults. Why younger people in particular? Energy drinks are used by younger people to increase their wakefulness and attention spans, getting an energy boost, studying, driving, and partying. There are some positive aspects of using energy drinks to improve mental performance due to the various ingredients working together.

A study of 36 volunteers consumed the Red Bull brand energy drink and showed a large improvement in concentration and memory of immediate events. Three different studies showed that combining glucose and caffeine improved concentration and memory as well as improved levels of tiredness and fatigue during times when high concentration and thinking is required.

Another study was conducted to look at the positive effects of energy drinks on mood. This study found that the three most common ingredients found in energy drinks, caffeine, taurine and glucoronate showed positive changes on both mood and concentration. The participant’s moods were assessed by a questionnaire that looked at vitality, social interaction and sense of well-being. The results showed that the study participants who consumed energy drinks had improved or maintained both mood and performance during times of stress and while performing fatiguing and demanding cognitive tasks as compared to study participants who received a placebo.

Another study also looked at what happens with energy drinks and sleepiness while driving over long periods of time, looking specifically at driving mistakes and lane swerving. This study found that those participants who consumed energy drinks were more alert and complained of less sleepiness than the group who was given the inactive placebo.


Just as there are positive effects to using energy drinks, there are also negative effects that need to be carefully examined and considered before using.

The heart and circulatory system is one area of concern. Caffeine acts as a stimulant to the body and causes the heart rate and blood pressure to increase.

  • A rapid heart rate (tachycardia) and abnormal heart rhythm (arrhythmia) occurs when more than 200 mgs of caffeine is taken in. One study tested 50 young men and women one hour before and after drinking a 250 ml sugar-free drink containing 80 mg of caffeine and a control group who had no caffeine. There was a 13% change in the average pressure in the blood vessels in those who drank the caffeine compared to less than 1% in the no caffeine group.
  • One study also showed that the walls of the aorta became stiffer and less flexible with caffeine.
  • Another side effect of caffeine is the risk of Myocardial Infarction or Heart attack. One study showed that there is an increased risk of heart disease in people who have more than 6 servings of caffeinated beverages per day.
  • One of the abnormal heart rhythms that can occur from taking in too much caffeine, especially from energy drinks, is atrial fibrillation, although ongoing studies are inconclusive. There have been reported cases of Atrial Fibrillation occurring after a sudden, rapid intake of energy drinks. The reason why it occurs, especially in young adults is, not yet known. The question remains, do those who get A-Fib after energy drinks have an already present medical risk of getting it or is it caused by the energy drink itself.

Another area to be concerned about is the negative effect energy drinks can have on sleep habits and sleepiness. As in all area’s regarding energy drinks, more study into sleep and energy drinks is needed.

  • One study of 197 students showed that people who combined caffeine (either from coffee of energy drinks) and soda’s reported waking up early in the morning and periods of sleepiness during the day time.
  • Another study showed that students who reported periods of sleepiness during the day had a 76% increase in the use of energy drinks. This study showed a connection between these students using their electronic gadgets late into the night, leading to the daytime sleepiness. This study needs to be evaluated further to take into account for the lack of sleep the night before and be corrected for number of hours slept.
  • Yet another study reported that energy drinks containing a low amount of caffeine, 30 mgs, caused a slower reaction time in the participants and also did not relieve the feeling of sleepiness.
  • The study also reported that using energy drinks to stay awake before an 8 hour sleep/recovery period had a negative impact on the efficiency/effectiveness of sleep and the total amount of sleep time.

The effects on thinking and decision making is also an area of concern because they can be used any time of the day or night and can be used alone or mixed with alcohol. There may be a relationship between the use of energy drinks and the drinking of alcohol. Let’s take a look at some studies.

  • A study of 137 physical education college students showed that 39.4 percent drank energy drinks 6 or more times in a 30 day period. 87.6 percent of these consumers mixed the energy drinks with alcohol. The participants stated that mixing the energy drinks with alcohol made the alcoholic beverages taste better.
  • Another study of 602 young adults and adolescents studied risk taking behavior and energy drink consumption. It was found that frequent use of energy drinks was related to problem behaviors such as risky sexual behaviors, use of marijuana, lack of wearing seat belts, frequent abuse of prescription drugs and alcohol as well as cigarettes.
  • A study of 1097 college students who drank energy drinks about 52 days a year were more at risk for becoming dependent on alcohol that those who did not consume energy drinks.
  • A study of 802 participants showed that drinking alcohol and energy drinks together increased the risk of drinking and driving. Participants who drank only alcohol as opposed to alcohol and energy drinks together, were reported to drink and drive less often than those who drank both.
  • Energy drinks have been found to reduce the alcohols depressive effect and act as a stimulant leading to the decreased realization that the person is impaired. This leads to more consumption of alcohol, which leads to a lack of understanding that one is impaired and then leads to poor impulse control.

More research and detailed studies are also needed in the area of energy drinks and alcohol and their effects on young adults.

Some research has been done regarding energy drinks and their contribution to obesity and fatty liver disease. Energy drinks contain carbohydrates. The body will normally take in the amount of carbohydrates it needs to remain healthy, if the person is healthy and lives an active lifestyle. Drinking energy drinks between meals as a supplement or substitute for water is not recommended. Studies have shown that liquid forms of carbohydrate do not make you feel full or satisfied. This can lead to eating more food and eliminate any benefits of exercise. This can lead to weight gain and eventually obesity and diabetes.

Caffeine consumption and the use of energy drinks can also lead to neurological problems.

  • A study released in 2002 showed that taking in 300 mg caffeine can make a person more tense and nervous. Increasing the caffeine intake to 400 mg increases nervousness and anxiety, especially when dealing with stressful situations.
  • A separate study reported that drinking more than 300 mgs of caffeine (the equivalent of 7 cups of coffee) was related to reports of hallucinations, compared to people who drank small amounts of caffeine (1-3 cups per day).
  • Other studies also suggest that energy drinks can lead to seizures and may contribute to strokes.

Energy drinks and caffeine can also lead to problems with the kidneys and muscles. It has been reported that energy drinks can cause a low blood potassium level because the energy drinks cause an increase in urination and the water loss can lead to a loss of potassium. The loss of potassium can lead to the muscles not working properly and can also cause abnormal heart rhythms. Energy drinks can also lead to dehydration and possible poorly functioning kidneys.


It is clear that educational programs are needed to present the facts about energy drink use, potential side effects and risks, especially when combining with alcoholic beverages. Research also needs to focus on how much energy drink is consumed by whom and how the different ingredients work together to create different effects. Most people are using energy drinks to stay awake and improve concentration without realizing that the short term benefits are quickly wiped away by the negative effects of increasing daytime sleepiness the day after use as well as a marked reduction in the ability to react in certain situations.

Additional research studies are needed into both the positive and negative effects of energy drinks. More research is needed into the ingredients in the energy drinks and they need to be listed on the containers so consumers can know exactly what they are drinking. It has also been suggested that more scientific evidence based research be conducted to develop an upper limit on the amount of caffeine that can be contained in any single serving of a beverage. Cola like drinks have a limit of 71mg per 12 ounce serving. However energy drinks do not currently have an upper caffeine limit because of the herbs and supplements contained therein. Accurate labeling of energy drinks, as well as placing any researched based negative effects on the labels as warnings would be a good start to educate consumers before using. Before using any energy drinks it is a good idea to talk to a healthcare provider to see what risks and benefits it has for you.


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