WARNING: This article is meant to be a quick overview and not a detailed guide on energy drinks and their effects. Professional medical advice should always be sought first before incorporating energy drinks into your routine.

Although energy drinks have been around for several decades, they seem to have exploded in popularity recently. The associated industry can now be measured in the billions of dollars with marketers taking aim at everyone from adventure athletes to average citizens, but is the hype backed by science and research or is it just a compelling gimmick? There are risks with each substance found in your favorite energy drinks, but there are also potential benefits from these substances. Let’s tone down the hype and look at some of the components of energy drinks and their effects.


This is the primary additive in energy drinks. Many drinks contain two to three times the amount of caffeine found in a cup of coffee or four times the amount in your average soda. Caffeine can take up to an hour to “kick in” and stays in the body for several hours (half-life three to seven hours). Absorption is fairly rapid in the gastrointestinal tract and may increase in obese males. The half-life and related effects can be prolonged in pregnant women and in children. Too much caffeine can cause a fast heart rate, anxiety, headache, shakiness, and inability to fall asleep. These effects may increase when the caffeine dose reaches 15 mg per kg (2.2 pounds) of body weight. Despite what you might think, there are lethal side effects that can occur at 150 to 200 mg per kg of body weight. Most recommendations favor no more than 200 to 400 mg of caffeine daily.

Many of the emergency room visits attributed to caffeine or energy drinks are related to elevated blood pressure and palpitations (fluttering of the heart). These adverse effects occur because caffeine acts as a stimulant by increasing epinephrine (adrenaline) and dopamine levels. Not only will this increase heart rate and blood pressure, but it can improve mental alertness. The epinephrine also stimulates glycogen breakdown to yield glucose (glycogenolysis) to use as fuel for the cells in our body. This can have short-term benefits by improving reaction time and increasing muscle contraction.

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For endurance athletes and survival situations, the biochemical processes of caffeine metabolism can encourage breakdown of glucose stored in muscle and fat (as glycogen) to provide extended periods of energy. The processes glycogenolysis and gluconeogenesis occur in the liver and are essential in making sugar when there’s a negative glucose balance. Additional caffeine intake can supplement the response in the short term by increasing alertness and in the long term by providing energy (glucose) when food sources may be scarce.


This is a Brazilian seed that contains caffeine. The seed is twice as potent as the coffee bean. This amount of caffeine contained in guarana isn’t typically figured into the total caffeine content of the drink. The recommended maximum dose is 300 mg. Exceeding this dose during pregnancy can cause miscarriages and birth defects.


This component gives you an energy boost up front and is probably meant to fill the gap until the caffeine starts to kick in. In many of the energy drinks, the amount of glucose/sugar/carbs per serving is similar to a can of soda or even fruit juice. In a survival situation, you may need to scavenge for sugar sources. Foods like honey or fruit might be the obvious choice, but don’t forget about starch. Starch is a complex carbohydrate made up of lots of glucose molecules bound together. Potatoes, corn, beans, and yams can all be options to help bolster your energy demands. If you’re diabetic, elevated blood sugar can cause fatigue and decreased alertness.

Vitamin B12 (Cyanocobalamin)

We generally get this vitamin from meat, fish, eggs, and dairy products. It’s a water-soluble vitamin that helps to build and maintain the nervous system and build red blood cells. When people are deficient in B12, they typically feel tired and depressed. Taking the supplement can boost your energy when you’re deficient in the vitamin, but it’s not thought to help otherwise.

Vitamin B12 is best given as an injection because it’s poorly absorbed in the gastrointestinal tract. If you plan to take a B12 pill, it’s best to use the gel cap and squirt its contents under your tongue for better absorption. A recommended daily dose is 2.4 mcg per day. Taking too much B12 is rare, but can cause side effects like diarrhea, low potassium, or swelling.

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Above: This chart compares the contents of some common energy drinks, as well as chocolate and more traditional beverages.

Other B Vitamins

Riboflavin (B2), niacin (B3), pantothenic acid (B5), and pyridoxine (B6) are all added to make the energy drink seem healthier. Although they may play small but important parts in proper body function, the addition of these substances hasn’t been shown to contribute to increased energy when they’re present to excess. Niacin has the largest potential for side effects among these B vitamins. It can cause flushing due to its release of histamine. Niacin can be found in poultry, legumes, and asparagus, to name a few. The maximum recommended daily dose of niacin is 3,000 mg, but most people will not tolerate the flushing associated with the drug.

Pyridoxine is important in building neurotransmitters and is involved in other metabolic processes; however, in excess, it can cause permanent neurologic damage. A maximum recommended dose of pyridoxine is 50 mg per day. This B vitamin can be found in poultry, fish, oranges, and cantaloupe. Riboflavin and pantothenic acid have no documented maximum dose. Riboflavin can be sourced from liver, heart, or kidneys as well as soybeans, almonds, and mushrooms. Pantothenic acid can be found in liver, heart, eggs, corn, and potatoes.


Taurine can be found in meat, fish, seaweed, and dairy products, and serves as a neurotransmitter depressant. It can help with mental clarity during overstimulation, but probably is added to energy drinks to help combat the jitters associated with elevated caffeine consumption. It can help with cardiovascular function and may help skeletal muscle function as well. No adverse effects from excess consumption have been reported that I’m aware of, but it’s generally recommended to stay under 3,000 mg per day.


This comes from the Ginseng root and is purported to reduce stress and fatigue, as well as aid in mental clarity and physical performance. Excess intake usually doesn’t cause a problem; however, it could cause gastrointestinal upset, headaches, bleeding, anxiety, and insomnia. Dosages range from 100 to 4,500 mg daily. Although ginseng has been used for centuries, science has yet to definitively prove its value. That being said, many consumers believe that it has a boost that helps them through their stressors.

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Above: Caffeine has significant effects on the liver, nervous system, and skeletal system by being structurally similar to an energy depleted molecule. Several biochemical pathways are involved in managing how caffeine affects hormones and manages glucose to maintain cellular function. 

Helpful or Overhyped?

So what compels people to consume energy drinks? Some people use them as part of their pre-workout routines. Most people’s workout routines last about an hour. The consumption of an energy drink 30 minutes before exercise may help because about 99-percent of the caffeine is absorbed in the first hour after consumption; however, it’s likely the glucose contained within the drink that gives you the initial lift at the beginning of the worvkout. The long half-life of caffeine may also help reduce fatigue in the recovery period. According to research, caffeine may improve performance in endurance sports as described earlier, but has no associated benefit with isometric exercise.

What about people who use energy drinks to stay awake while driving? Again, the sugar may provide the initial benefit, but may be responsible for the “crash” that occurs when the body uses up the sugar. The 5-Hour Energy shots advertise a boost without the crash mainly because they contain no glucose. Most people wait until they’re falling asleep at the wheel before they decide to imbibe in their favorite caffeinated beverage. Perhaps preplanning during long road trips and carefully considering any tendencies to fall asleep at the wheel would encourage you to consume the energy drink a few hours before you need it.

Lastly, what about the use of energy drinks in a survival situation? The adrenaline of the apocalypse may be a bit of a sensory overload for the first 24 hours, but you may need a boost as the fatigue sets in. It would be reasonable to ingest an energy drink in this situation as the first 72 hours of the emergency wears you out. Drinking more than two in a 24-hour period may be counterproductive due to potential side effects such as palpitations, jitteriness, and anxiety in an already-heightened hormone state.

Be reasonable when drinking energy drinks on an empty stomach and during periods of dehydration, as these situations can increase the risk of side effects, such as heartburn from the caffeine. As the survival situation lingers into weeks, it’s likely that the effect of the caffeine will wane as the body builds tolerance to the chemical. Some studies suggest that tolerance to caffeine ingestion occurs after just seven days of continued use.

Caffeine can be a useful drug when used sparingly and appropriately. There is science to back caffeine’s use for alertness and as a benefit for endurance athletes. My opinion is that the popular rise in energy drinks has been bolstered by excellent marketing and not backed by irrefutable science. Speak with your doctor before incorporating energy drinks into your regimen or consuming regularly to ensure their effects and ingredients won’t clash with any medications you’re on or preexisting conditions you have. After all, do you really have wings?

About The Author

David Miller, DO, FACOI, is an internist in private practice. Diagnosed with Type 1 diabetes in 1990, he has a unique perspective on patient care and disease management. Experiences away from the office include being a fight doctor for regional MMA bouts and a team physician for a Division I university in west central Illinois. Dr. Miller is an instructor for the Civilian Crisis Response Team (medical section) based out of Indianapolis.

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