High-energy drinks have become more and more popular over the past few years, due to a recipe that few could resist: sweet as juice, stronger than coffee.

Recently, scientists at the Johns Hopkins University have done some serious research concerning the widely spread beverages and reached the conclusion that they contain potentially harmful levels of caffeine. Some drinks are said to have up to 14 times the caffeine of a regular can of soda, which is the equivalent to seven cups of extra-strong coffee.

Dr. Roland Griffiths wrote in the journal „Drug and Alcohol Dependence” that the drinks should carry warning labels, displaying the caffeine content and also the possible health risks that include nervousness, anxiety, insomnia, rapid heartbeat and tremors.

The energy drinks that contain caffeine are marketed as supplementary (and not soft) drinks, therefore they are neither required to comply with the United States Food and Drug Administration’s maximum caffeine content for soda and other beverages (71 milligrams per 12-ounce can), nor compelled to label it.

Unfortunately, they are continuously targeted at teens and young adults, who are easily impressionable and completely unaware of the dangers.

Spokesmen from top-selling energy drinks organizations stated that their products are aimed only at young adults and not at children, adding that the study unfairly characterizes all caffeinated energy beverages into a single unfavourable presentation.

"It's unfortunate that the authors of this article would attempt to lump all energy drinks together in a rhetorical attack when the facts of their review clearly distinguish the mainstream responsible players from novelty companies seeking attention and increased sales based solely on sensationalistic names and extreme caffeine content," Craig Stevens, a spokesman with the American Beverage Association, said in a statement.

Red Bull, which is the most recognized energy drink on the market, was launched in Austria back in 1987, followed by its launch in U.S. 10 years later. Since then, the market for caffeinated energy beverages has suffered a massive expansion worldwide, accounting for a $5.4 billion industry. The products outline the image of a high-energy lifestyle, claiming to increase strength, endurance and toughness.

Presently, given that the combination of energy drink plus alcoholic beverage are becoming more and more popular, researchers are worried that they could serve as a gateway to more serious abuse of drugs.