“Your Health Checkup” is our online column by Dr. Douglas Zipes, an internationally acclaimed cardiologist, professor, author, inventor, and authority on pacing and electrophysiology. Dr. Zipes is also a contributor to The Saturday Evening Post print magazine. Subscribe to receive thoughtful articles, new fiction, health and wellness advice, and gems from our archive.
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I exercise every morning before I begin work. Some mornings I just feel beat, too tired to pump iron or bike, so in addition to my usual yogurt, banana, and cup of morning coffee, I’m tempted to chug down an energy drink to prime my motor. However, knowing how dietary supplements can be adulterated with unwanted and even dangerous contaminants, I’m leery of doing that. In addition, I’ve written that “Energy drinks are in a different class [of dietary supplements]. They often contain caffeine at significantly higher concentrations than coffee and tea, along with other energy-boosting substances, such as guarana, sugar, ginseng, yohimbine, and ephedra … Multiple reports relating the temporal association between ingesting energy drinks and heart rhythm problems, including sudden death, are of major concern.”
More and more people are consuming energy drinks; their market value is projected to increase to more than $60 billion by 2021. About a third of U.S. teenagers aged 12-17 consume energy drinks regularly. The number is even higher – 45 percent — for military personnel. Energy drinks sent more than 10,000 people to emergency departments in 2007. That number had doubled by 2011. The Food and Drug Administration has attributed over 30 deaths to energy drinks.
What is it about energy drinks that makes them dangerous? A new study helps answer that question.
Researchers at the University of the Pacific in California had 34 young (22 years old) healthy volunteers consume two 16-ounce bottles of one of two brands of caffeinated energy drinks or lime juice with cherry flavoring placebo on three successive days with a six-day washout period in between. The researchers measured blood pressure and recorded an electrocardiogram (ECG) every half hour for four hours after drink consumption.
They found that the caffeinated energy drinks increased systolic blood pressure (top number) by five mmHg and diastolic blood pressure by four mmHg compared with placebo. While the blood pressure change may seem small, a sustained increase in systolic blood pressure of only two mmHg is associated with a seven percent increase in the risk of dying from a heart attack and a ten percent increased risk of dying from a stroke.
After each heartbeat, the heart requires a rest period to prepare for the next contraction. This time period measured on the ECG is called the QT interval and when prolonged, can increase the risk of sudden cardiac arrest. In the study, caffeinated energy drink A prolonged the QT interval by 6.1 msec compared with placebo and caffeinated energy drink B prolonged the QT interval by 7.7 msec compared with placebo. Once again, the changes may seem trivial, but in susceptible individuals, that increase in QT may be just enough to tip the person into having a life-threatening rapid heart rhythm leading to sudden cardiac arrest and death.
What’s the take-home message? My advice is to avoid consuming ALL caffeinated energy drinks. If you feel tired, your body is “talking to you” and you should listen to it. Rest, or if you must be active, pace yourself. Between consuming plastic and ultra-processed foods, skipping breakfast, and eating eggs, we have enough risks on our plates —literally! Why add more by consuming caffeinated energy drinks? Avoid them.
Featured image: Shutterstock
“Your Weekly Checkup” is our online column by Dr. Douglas Zipes, an internationally acclaimed cardiologist, professor, author, inventor, and authority on pacing and electrophysiology. Dr. Zipes is also a contributor to The Saturday Evening Post print magazine. Subscribe to receive thoughtful articles, new fiction, health and wellness advice, and gems from our archive.
Order Dr. Zipes’ new book, Damn the Naysayers: A Doctor’s Memoir.
During more than 50 years of practicing cardiology, I have counseled hundreds, if not thousands, of patients complaining of palpitations and heart rhythm problems to reduce or eliminate intake of caffeinated beverages, particularly coffee. Caffeine, the major ingredient in coffee, is a known stimulant that triggers the body’s fight or flight response, with an outpouring of adrenaline and other substances. Three fourths of my physician colleagues proffer the same recommendation. Despite caffeine’s stimulating action, recent evidence suggests we may have been wrong.
An extensive review of multiple studies concluded that, barring about 25% of individual cases that exhibit a clear temporal association between heart rhythm episodes and caffeine intake, coffee and tea appear to be safe. A regular intake of up to three cups of coffee a day may even protect against heart rhythm disorders [PDF]. One large study of 228,465 participants showed that the incidence of atrial fibrillation decreased by 6 percent for every three cups of coffee a day. Another study of 115,993 patients showed a 13 percent reduction in the risk of atrial fibrillation.
One report concluded that drinking three to four cups of coffee daily compared with no coffee intake reduced death and cardiovascular disease by almost 20 percent. Coffee was also associated with a reduced risk of some cancers and neurological and liver disorders. Interestingly, patients with Parkinson’s disease had significantly lower serum concentrations of caffeine and its metabolites than subjects without the disease, despite consuming the same amount of caffeine. It’s not known whether this response might be due to the drugs they were taking or a specific effect of early Parkinson’s disease on caffeine metabolism.
Energy drinks are in a different class. They often contain caffeine at significantly higher concentrations than coffee and tea, along with other energy-boosting substances, such as guarana, sugar, ginseng, yohimbine, and ephedra. Guarana, particularly, has a higher caffeine concentration than coffee and contains theophylline, which also has stimulant properties. Multiple reports relating the temporal association between ingesting energy drinks and heart rhythm problems, including sudden death, are of major concern. Energy drinks may also increase the risk of blood clots. My recommendation is to avoid all energy drinks.
Some caution about accepting these positive results is advised since extrapolating data from healthy volunteers in the studies to individual patients can be risky. Differences in individual susceptibility to the effects of caffeine, various health conditions, and drugs could trigger caffeine-induced heart rhythm problems, so those with a clear temporal association between coffee intake and heart rhythm episodes should abstain. A transient blood pressure rise can occur in susceptible individuals. Also, caffeine tolerance developed by regular long-term coffee drinkers may explain some of the lack of association with heart rhythm problems. For example, I enjoy a double espresso after dinner each night and still fall quickly asleep (the wine helps!), but I have been drinking coffee regularly for many years and would not recommend this for new coffee drinkers.
In conclusion, those of you who are coffee and tea lovers can rest assured that, along with dark chocolate and red wine, caffeine intake is likely to be safe, and maybe even beneficial.
But wait! This column is mostly about caffeine and the heart. What about caffeine and cancer? See next week’s column.