They cause electrical disturbances—and it's not from the caffeine.
tops of cold canned beverages

You probably know that energy drinks aren't super good for you. They're often high in sugar and full of artifical ingredients, so you're better off getting that caffeine kick from a cup or two of coffee, or just sipping on infused water for a natural pick-me-up. However, if you still find yourself turning to a can or tiny bottle of energy drink in the afternoon, here's a reason to finally give it up: It turns out those energy drinks could be bad for your ticker, and not because of the caffeine content.

According to a recent study published in the Journal of the American Heart Association, researchers found that three to four hours after drinking 32 ounces of energy drinks, the heart's electrical activity appeared abnormal compared to those who were drinking a placebo drink. What's more, it wasn't just a matter of one particular kind of energy drink brand used. Two different energy drinks marked the same results. Active ingredients in the drinks (aside from caffeine) included "taurine (an amino acid), glucuronolactone (found in plants and connective tissues) and B-vitamins."

The study called for participation from 34 healthy volunteers between 18 and 40 years old. Each had to drink 32 ounces of one of two commercially available energy drinks, or a placebo drink on three separate days and within a 60-minute period (but no faster than one 16-ounce bottle within 30 minutes, so they weren't pounding them). Then they were monitored for four hours. The result? Abnormal heartbeats (also known as arrhythmia) were detected in the energy drink users, but not in the placebo participants. And rather than lasting a short time and then dissipating, the heartbeat changes lasted the entire four hour period.

This suggests that energy drinks were responsible for the electrocardiographic alterations. The study discounted the possibility that the caffeine could have been responsible for the effects, since previous studies have found that caffeine intake under 400 milligrams doesn't cause electrocardiographic changes, and the drinks only had between 304 and 320 milligrams of caffeine per 32 fluid ounces.

"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," said lead author Sachin A. Shah, Pharm.D., professor of pharmacy practice at University of the Pacific, Thomas J. Long School of Pharmacy and Health Sciences in Stockton, California.

Though more research needs to be conducted to confirm the association, it's clear that something about energy drinks does not do well for your heart. To stay cautious, choose java or green tea when you're in need of some energy and flavor, or go for one of these four natural energy boosters instead.