A study of the effects of energy drinks on the heart was presented at a meeting of the American Heart Association in Phoenix, AZ. Described here, this preliminary report suggests that caution is advised for anyone with a heart condition or a family history of such if they're tempted to indulge.
Dr. Sachin A. Shah from Pacific's Thomas J. Long School of Pharmacy and Health Science, led the research. He and colleagues studied 27 healthy volunteers aged 18 to 40 years. They had the participants drink either two cans of an energy drink, or an equal volume of a drink containing only panax ginseng (which was an ingredient in the energy drink), or a placebo drink. They consumed these beverages once a day, every six days over a three-week period. Neither the participants nor the researchers knew who got which drink.
The subjects' heart rhythms and blood pressures were measured just before and four times in the next six hours after consumption. What they found could be concerning for some. Participants who had the real energy drink experienced a slight increase in blood pressure and a significant increase in a marker of abnormal heart rhythm — the QTc interval, and these effects lasted a couple of hours post-ingestion.
Neither of these effects occurred after the participants drank either the ginseng-laced or the placebo beverages. So the herbal addition wasn't responsible for the negative effects.
A link between energy drinks and cardiac problems is not a new concept. An Australian study also found an association between visits to an emergency room for cardiac symptoms and energy drink consumption. And combining these drinks with alcohol can mean greater consumption, and likely more negative effects.
So, while the results of the present study must be considered preliminary, there has certainly been sufficient previous research to suggest that it would be wise for those with cardiac issues to minimize or avoid energy drink consumption.