Consuming just one energy drink could increase the risk of heart attack and stroke within 90 minutes, a new study finds.
Researchers at the University of Texas at Houston say the drinks contain narrow blood vessels that restrict blood flow to vital organs.
Previous studies have linked energy drinks – such as Red Bull, Monster and 5-Hour Energy – to gastric, nerve and heart problems.
However, the team says its results are among the first to shed any light on the possible mechanism that links the high consumption of energy drinks with an increased metabolic syndrome.
A new study found that consuming energy drinks can narrow blood vessels, restrict blood flow and increase the risk of heart attacks and strokes (image file).
For the study, the team studied 44 students from McGovern Medical School at UTHealth.
The participants were all over 20 years old and smoked as "healthy".
The researchers wanted to test the function of the endothelium, a cell layer that lines the surface of blood vessels.
According to Los Angeles's Cedars-Sinai Medical Center, endothelial dysfunction has been shown to be an indicator of heart attack, as the arteries can not fully expand.
The team tested participants' endothelial function before each student drank a 24-ounce energy drink and then 90 minutes later.
During the second test, the researchers examined the artery-stretching students, an ultrasound that measures the overall health of the blood vessels.
In just 90 minutes, the internal diameter of the blood vessels had been reduced by almost half on average.
The team points out that the negative effects on blood vessels could be due to the effects of ingredients in energy drinks – including caffeine, taurine, sugar and other herbs – on the endothelium.
Most energy drinks contain a high sugar content. For example, a 12-ounce tin of Red Bull contains 37 grams of sugar – that's more than nine teaspoons.
Research has shown that high blood sugar levels can cause blood vessels to contract more than normal, reducing the amount of blood reaching vital organs.
These drinks also contain 80 milligrams of caffeine per 250 milliliters – about as much as 2.5 cans of Coca-Cola.
Caffeine can also cause blood vessels to contract and release adrenaline, a hormone that can temporarily increase blood pressure.
According to the National Center for Complementary and Integrative Health, nearly a third of American teenagers between the ages of 12 and 17 regularly consume energy drinks.
"As energy drinks become more popular, it is important to examine the effects of these drinks on those who drink them frequently, and to better determine what, if any, is a safe use pattern," said Dr. John Higgins, professor of medicine at McGovern School.
In recent years, scientists have identified some negative effects that can cause energy drinks.
A study conducted in April 2017 by the California Grant USAF Medical Center in California found that a 32-ounce energy drink can cause dangerous arrhythmias. This is a condition where the heart beats with an irregular or abnormal rhythm.
A study conducted by the University of Waterloo, Ontario, Canada, in February 2018 found that half of the Canadian teenagers who consumed energy drinks reported health issues, including palpitations, nausea and, in rare cases, seizures.
The new findings will be presented at the American Heart Association's 2018 Scientific Sessions in Chicago. which takes place from the 10th to the 12th of November.