Some Energy Drinks May Increase Blood Pressure and Change Heart Rhythms, Study Says

Consuming energy drinks may increase blood pressure and modify the heart rhythms of healthy humans, according to new research.

The finding, presented yesterday at a meeting of the American Heart Association in Phoenix, adds to growing concern over energy drinks that combine ingredients like caffeine, guarana and ginseng into a potent stimulant.

Researchers tested 27 healthy adults under age 40 in the small study. Participants who consumed two energy drinks saw a statistically significant increase in abnormal heart behavior and a rise in blood pressure when compared to a control group given a placebo. Both of these conditions lasted two hours.

The new research is far from the first study to caution that energy drinks may lead to adverse health effects. A 2015 study in the journal JAMA found that energy drinks raised blood pressure and caused a stress hormone in young people. Researchers behind the new study recommended that consumers, particularly young people, await further research before regularly drinking energy drinks.

Write to Justin Worland at justin.worland@time.com.