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The same stuff that gets your heart pumping in the morning might just stop it altogether.
A new report from the American Heart Association reveals that drinking just four 8-ounce servings of a typical energy drink can lead to a spike in blood pressure and cardiac arrhythmia. The findings, published in the Journal of the American Heart Association, represent the largest controlled study on the heart-related effects of energy drinks in young, healthy people.
Researchers gathered 34 volunteers between 18 and 40 years old and took initial readings of each of their heart rhythm and blood pressures. Participants were randomly assigned to drink either 32-ounces of an energy drink or a placebo drink containing carbonated water, lime juice and cherry flavoring, and told to consume the full amount in just one hour, but no faster than 16-ounces per half hour. Researchers recorded electrocardiogram and blood pressure data every 30 minutes for four hours following drink consumption.
Using a rating system called QT intervals, the scientists measured the length of time it took the heart’s ventricles to beat again. An interval too short or too long could result in a life-threatening irregular heartbeat.
The volunteers who consumed one of two commercially available energy drinks for the study had QT interval readings that were 6 milliseconds or 7.7 milliseconds higher — even after four hours — compared to placebo drinkers, confirming past studies showing sustained QT interval changes and vascular damage among energy drink consumers. Researchers also reported a “significant” 4 to 5 mm Hg increase in systolic and diastolic blood pressure.
Usually, consuming 400 milligrams or less of caffeine should not make an impact on the heart beat, and the energy drinks used in the study contained between 304 and 320 milligrams of caffeine per 32-ounces. However, energy drinks typically contain a number of supplements thought to boost energy, including B-vitamins, glucuronolactone and taurine, which can have adverse affects on cardiovascular health when combine with caffeine.
“We found an association between consuming energy drinks and changes in QT intervals and blood pressure that cannot be attributed to caffeine,” says lead author Sachin A. Shah, professor of pharmacy practice at University of the Pacific in Stockton, California. “We urgently need to investigate the particular ingredient or combination of ingredients in different types of energy drinks that might explain the findings seen in our clinical trial.”
Other studies have shown that energy drink consumption is on the rise in the US, especially among teens and young adults: Men aged 18 to 34 are the $70 billion industry’s biggest consumers, while an estimated 30 to 50 percent of teenagers aged 12 to 17 consume energy drinks regularly.
“Energy drinks are readily accessible and commonly consumed by a large number of teens and young adults, including college students,” adds co-author and pharmacy professor Kate O’Dell. “Understanding how these drinks affect the heart is extremely important.”
Researchers note limitations, including the short-term study period and the fact that only healthy individuals were studied. They also point out that their study isolated the energy drinks, which, in reality, are frequently combined with other potentially harmful substances such as alcohol.
Experts are calling on physicians to take note, especially for patients who already suffer from blood pressure and heart-related illnesses.
“The public should be aware of the impact of energy drinks on their body especially if they have other underlying health conditions,” says Shah. “Healthcare professionals should advise certain patient populations, for example, people with underlying congenital or acquired long QT syndrome or high blood pressure, to limit or monitor their consumption.”
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