Consuming only one energy drink could increase the risk of heart attack and stroke in 90 minutes, a new study concludes.
Researchers at the University of Texas at Houston say they drink narrow blood vessels, which limits blood flow to vital organs.
Previous studies have linked energy drinks – such as Red Bull, Monster and 5-Hour Energy – to problems with the stomach, nerves and heart.
But the team says its findings are among the first to rely on possible mechanisms that link high consumption of energy drinks to an increased metabolic risk syndrome.
For the study, the team looked at 44 students from the McGovern Medical School at UTHealth.
Participants were all in their twenties, not smokers, and classified as "healthy," reports MailOnline.
The researchers wanted to test the function of the endothelium, a layer of cells that direct the surface of the blood vessels.
According to the Cedars-Sinai Medical Center in Los Angeles, endothelial dysfunction has been shown to be an indicator of heart attack because the arteries are not able to dilate completely.
The team tested the endothelium function of the participants before each student drank a 24-ounce energy drink, and then 90 minutes later.
During the second test, the researchers looked at the dilation mediated through the arterial artery, an ultrasound that measures the overall health of the blood vessels.
In only 90 minutes, the internal diameter of the blood vessels, on average, was reduced by almost half.
The team suggests that a negative effect on blood vessels may be associated with the effects of ingredients in energy drinks – including caffeine, taurine, sugar and other herbs – on the endothelium.
Most energy drinks contain high levels of sugar. For example, one Red Bull 12 kuna contains 37 grams of sugar – equivalent to more than nine spoons.
Research has shown that a high blood sugar level can make blood vessels more than normal, reducing the amount of blood reaching vital organs.
These drinks also have 80 milligrams of caffeine at 250 milliliters – about the same as the 2.5 cans of Coca-Cola.
Caffeine can also cause blood vessels and the release of adrenaline, a hormone that temporarily can increase blood pressure.
According to the National Center for Complementary and Integrative Health, nearly one third of American teenagers between 12 and 17 regularly consume energy drinks.
"As energy drinks are becoming more and more popular, it's important to study the effects of these drinks on those who drink them often and better determine what, if there is, a safe model of consumption," said Dr. John Higgins, professor of medicine at McGovern School.
In the past few years, scientists are considering several ill effects that can be caused by energy drinks.
A study from the US Medical Center "David Grant USAF" in California in April 2017 found that an energy drink of 32 inches can cause a dangerous arrhythmia, a condition in which the heart is affected by an irregular or abnormal rhythm.
And a February 2018 study from Waterloo University in Ontario, Canada, found that half of Canadian teenagers who consumed energy drinks reported health problems, including rapid heart control, nausea and, in rare cases, attacks.
New findings will be presented at scientific meetings of the American Heart Association in 2018 in Chicago, which will be held from November 10 to 12.