» RELATED: Energy drinks pose serious and scary health risks, scientific review shows
The researchers also recorded artery flow-mediated dilation using an ultrasound that reveals overall blood vessel health before and after the 90-minute mark.
What they found was an acute impairment in vascular function after just one drink. At baseline, vessel dilation was, on average, 5.1 percent in diameter. After 90 minutes and one drink later, vessel dilation fell to 2.8 percent in diameter.
According to lead researcher John Higgins, that reduction can restrict blood flow and oxygen delivery.
"It's more work for the heart and less oxygen supply for the heart. This could explain why there have been cases where kids have had a cardiac arrest after an energy drink," he told HealthDay.
The reduction’s effects can ultimately lead to an increased risk of high blood pressure, coronary heart disease, stroke or rheumatic heart disease, in addition to other vascular diseases.
While the study is small and only examines the acute effects of energy drinks, Higgins and his colleagues believe the combination of caffeine, taurine, sugar and other ingredients are responsible for any negative effects.
» RELATED: What is Death Wish Coffee? 'World's strongest coffee' soaring into space
As the American Heart Association has previously noted, "added sugars contribute zero nutrients but many added calories that can lead to extra pounds or even obesity, thereby reducing heart health."
And while caffeine has also been linked to health benefits, the recommended daily limit is 400 milligrams for adults. But some energy drinks contain more than 200 milligrams per ounce, including the concentrated so-called "energy shots."
Still, industry groups argue their drinks are safe.
"Mainstream energy drinks contain about half the caffeine of a similarly sized cup of coffeehouse coffee, and have been extensively studied and confirmed safe for consumption by government safety authorities worldwide," William Dermody, spokesman for the American Beverage Association, said in response to the study. "Nothing in this preliminary research counters this well-established fact."
The researchers are scheduled to present their findings, considered preliminary until published in a peer-reviewed journal, on Monday, Nov. 12.