GAINESVILLE, Fla., Aug. 2 (UPI) -- Red Bull, Monster and other energy drinks have become a popular alternative to coffee in recent years for those who need an extra jolt to get moving, but increasing evidence suggests the beverages have a bad effect on heart health.
The high levels of caffeine in energy drinks, among other chemicals, can lead to abnormal heart rhythms and other cardiovascular events, report doctors at the University of Florida in a case study recently published in the Journal of Addiction Medicine.
Doctors at UF write in the study that a 28-year-old man came to the hospital with atrial fibrillation and rapid ventricular response -- he had a very high heart rate and an abnormal heart rhythm -- both of which are common and can lead to health complications if not treated.
The abnormal heart rhythm was resolved within 48 hours, and a check-up one year later showed no other heart or health issues, though his doctors report the two Monster energy drinks and two or three beers he consumes every day likely was connected to his trip to the hospital.
"We believe that energy drink consumption played a key role," the doctors write in the study, based on 160 milligrams of caffeine in Monster being four times higher than that of coffee.
The high level of caffeine in energy drinks has been cause for concern for several years, with a study in 2010 finding one brand contained 505 milligrams of caffeine in one container, which is the equivalent contained in 14 cans of Coca-Cola.
Previous studies have also shown energy drinks change the way the heart beats, but the complete effects of the beverages are not completely understood and trips to the hospital are not unheard of for their biggest consumers.
Another study in March, conducted at the University of the Pacific, found participants who drank energy drinks had a statistically significant increase in a marker of abnormal heart rhythm, as well as a slight increase in blood pressure, for about two hours after consumption. The changes to heart activity suggest the drinks pose a health risk, researchers said.
"I see these kids coming in not infrequently with palpitations which subsequently resolve with discontinuation of the energy drinks," Dr. Dermot Phelan, medical director at Cleveland Clinic's Sports Cardiology Center, told CBS News.