Can these popular beverages affect your ability to practice medicine?

In recent years, there’s been a dramatic increase in the consumption of energy drinks. As a hard-working physician looking for an energy boost, it may be tempting to plunk a few bucks down at the convenience store for 5-Hour Energy shots, Red Bull, Monster Energy, or something similar—but is this a good idea? Think for a moment: Do you really want to be wired on energy drinks before seeing patients? And what exactly are the long- and short-term effects of these beverages?

Although research on energy drinks is still emerging, current data on their health effects are limited. Nevertheless, experts are concerned about these beverages, which are essentially unregulated by the FDA. Other countries have tried to rein in energy-drink manufacturers using regulations on labeling, distribution, and sale. Stakeholders are particularly concerned over the caffeine content in these products.

This begs the question, how healthy are these energy-boosting drinks, exactly? And especially for a physician who is often responsible for the wellbeing of others.

Composition

Energy drinks typically contain vitamins, glucuronolactone (a glucose metabolite), and herbal extracts, as well as two main active ingredients—taurine and caffeine, which have been shown to boost athletic performance. Caffeine modifies physical performance and increases cardiovascular measures, such as blood pressure and heart rate. It also combats fatigue and enhances endurance, which is appealing to athletes and busy professionals alike. Of note, caffeine content in energy drinks ranges widely.  

For example, a full bottle of 5-Hour Energy has a caffeine content of 207 mg, Red Bull 111 mg, and Monster Energy 86 mg. Compare this with the 100-150 mg of caffeine in a standard 8-oz cup of coffee.

Energy drinks also contain taurine, an amino acid and neurotransmitter that has also been proven to improve athletic performance and possibly reduce blood pressure levels. In addition, energy drinks contain loads of sugar (25–30 g/240–250 mL), including glucose with fructose or maltodextrin and fructose, which can boost energy levels in exercisers.

Emergency room visits

In the United States, the Drug Abuse Warning Network (DAWN) has been surveilling the number of emergency department visits secondary to energy drinks, which has doubled during the past few years. In 2011 alone, 20,783 emergency room visits related to energy drinks were reported, with more than one-half (58%) of these visits attributable solely to energy drinks. Nevertheless, detailed data on these visits are unavailable, and potential presentations, such as allergy or cardiovascular adverse effects, are unclear.

In an American College of Sports Medicine (ACSM) Contemporary Issues white paper published in Current Sports Medicine Reports, health experts—led by John. P. Higgins, MD, McGovern Medical School at The University of Texas Health Science Center at Houston (UTHealth), Houston, TX—wrote the following about energy drinks:

“Despite high market demand, the current evidence for safety, efficacy, and performance benefits is unsystematic and often contradictory, given different protocols and types of products consumed: this makes it difficult to draw firm conclusions. Also, much of the available literature is industry sponsored. One major concern with energy drinks is that they often contain high concentrations of caffeine.”

Cardiovascular effects

In one low-power, NIH-funded study (12 men, mean age: 21.83 years; 3 women, mean age: 24.00 years), researchers assessed the effects of three different types of energy drink (Monster, Red Bull, and 5-hour Energy) on cardiovascular and physical performance variables in recreational exercisers at rest and during treadmill testing. Although researchers noted no differences in diastolic blood pressure, oxygen consumption, ratings of performance, and heart rate, they found that systolic blood pressure readings did increase.

Blood pressure levels for all three energy drinks were higher compared with placebo by a mean of 8.81 mmHg (about a 5% increase). Specifically, Monster yielded an average increase of 9.54 mmHg; Red Bull, an average of 8.18 mmHg; and 5-Hour Energy, an average of 8.07 mmHg. Moreover, energy drinks increased systolic blood pressure at rest by an average of 3.84 mmHg.

The authors suggested that the effects of energy drinks on blood pressure may be unhealthy. Other researchers have shown that energy drinks increase norepinephrine levels by 74%, resulting in higher heart rates, blood pressure, glucose mobilization, and blood flow to skeletal muscle.

Neurological effects

In a low-power, randomized, crossover study (n = 10), Italian researchers assessed the effects of energy drinks on measures of anxiety and depression in healthy, young adults via the Beck Anxiety Inventory and Beck Depression Inventory II, respectively. According to their findings, participants experienced a “minimal level of anxiety” post-libation. Furthermore, there was also a slight increase in maximum heart rate after energy drink intake. The authors cautioned that energy drinks could represent a health risk, but further research is needed.

Other effects

In what amounts to a position statement, the ACSM cautioned against the use of energy drinks—especially in children and adolescents in its white paper.

Here are some specific health concerns, grouped loosely by organ system, that are cited among overindulgent energy-drinkers:

• Prolonged QTc interval, ventricular arrhythmias, atrial fibrillation, and sudden cardiac death
• Coronary artery spasm, hypercoagulability, coronary artery thrombosis, endothelial dysfunction, and aortic dissection
• Reversible cerebral vasoconstriction, intracerebral hemorrhage, and epileptic seizures
• Gastrointestinal distress and elevated liver enzymes in those with liver disease
• Rhabdomyolysis, acute renal failure, and metabolic acidosis
• Obesity and hyperinsulinemia (remember energy drinks are packed with sugar)
• Acute psychosis, trouble sleeping, and association with risky behavior (ie, driving fast, sexual risk taking, and drug use)

Of note, many of these concerns are based on observations, and when energy drinks were formally studied investigators found that covariates could yield bias results. Moreover, researchers of many of these studies recruited participants who are younger than the typical physician population, results may be similar among doctors.

Bottom line

Energy drinks, however tempting, are likely unhealthy if consumed in excess. Moreover, the benefits of energy drinks are probably far outweighed by their chronic negative health effects. Some of these effects—like heart disease and obesity—are more insidious. Other effects—such as anxiety or upset stomach—could immediately deter you from seeing patients.

Perhaps Dr. Higgins and colleagues put it best:

“Energy drinks are frequently consumed and there are reports of morbidity and mortality associated with their consumption. In particular, individuals known to be more susceptible to adverse events include those of young age, small stature, caffeine-naïve or caffeine-sensitive, pregnant or breastfeeding women, those with certain medical conditions and/or taking certain medications, consuming multiple energy drinks in one session, and those with underlying cardiovascular or other diseases…Although most healthy adults can consume an energy drink without any significant, negative, acute health effects, the long-term effects of chronic consumption have not been well studied.”