Energy drinks are marketed towards hardworking people who would quite like a boost in, you guessed it, energy - which can often feel like all of us. However, most of that "energy" derives from two main ingredients: sugar and caffeine. On average, an energy drink will contain up to 80 milligrams of caffeine, which is about the same amount as a cup of coffee. (For a bit of perspective, a 2006 study found that the average 12-ounce soda contains between 18 - 48 milligrams of caffeine.)
Beverages like Red Bull and Lucozade are designed to restore fluids lost during activity, and manufacturers claim the ingredients increase stamina and overall performance. They're usually aimed at students, athletes, and just anyone looking for an extra energy kick.
Red Bull began distributing what would be the most renowned energy drink back in 1997. According to its manufacturer, revenue doubled each year and in 2000, even reached over $1 billion. Although Red Bull has consistently been the number one product in the energy drinks market, a number of other companies have launched their own energy drink lines. And many of these are endorsed by fitness bloggers and celebrities.
Learn more about how energy drinks affect your heart:
Now as we all know, drinking that much sugar and caffeine on a daily basis can be pretty horrific for your health. But there are a lot more downsides to energy drinks than you probably thought.
Previous studies have already linked them to stomach, nerve, and heart problems. But now a research team from the University of Texas is claiming their findings are among the first to fully first to fully understand the mechanism linking an increased risk in metabolic syndrome to the energy drinks you consume.
Worryingly, they discovered that having just one can of energy drink could narrow your blood vessels in just 90 minutes. This would restrict blood flow to vital organs, leading to some pretty debilitating health problems like heart attacks or strokes.
For the study, the team looked at 44 students from the McGovern Medical School (part of the University of Texas). They were all non-smokers and in their twenties; all classified as "healthy".
Researchers wanted to test the impact of energy drinks on the endothelium, a layer of cells lining the surface of veins, arteries, and other blood vessels. After testing the subjects' regular endothelial function, the participants were then asked to drink a single 24-ounce energy drink. Following a 90 minute wait, the team discovered that the internal diameter of blood vessels was - on average - nearly half as wide.
But why was this the case? Well, the team suspects that this could be due to the ingredients in most energy drinks (eg. caffeine, sugar, taurine, and other herbals). High blood sugar, for example, has been shown in previous studies to cause vasoconstriction (the narrowing of blood vessels), leading to less blood reaching vital organs.
"As energy drinks are becoming more and more popular, it is important to study the effects of these drinks on those who frequently drink them and better determine what, if any, is a safe consumption pattern," says Dr John Higgins, a professor of medicine at the McGovern School where this experiment was carried out.
The findings from this study (and from two other studies carried out in April 2017 and February 2018) will be presented and discussed further at the American Heart Association's Scientific Sessions 2018 in Chicago, which will take place later this month.