Highly caffeinated energy drinks market themselves as sources of increased energy and concentration. Their websites feature high-flying motorcyclists and upside-down skateboarders as dynamic embodiments of all that concentrated energy.

"In the United States, these energy drinks have not had any warnings. In Europe, it's been more cautionary,” says Maher Karam-Hage, M.D., medical director of the Chelsea-Arbor Treatment Center, a joint program of the U-M Health System and Chelsea Community Hospital. He notes that France has banned some of the drinks and other countries have placed restrictions on them.

The energy drinks typically contain sugar, caffeine, and taurine, a sulfur-containing amino acid. Some countries have raised concerns about the amount of caffeine in the drinks and the uncertain health effects of taurine. Energy drinks are different from sports drinks, which tend not to have caffeine or taurine and are lower in carbohydrates.

While Karam-Hage stops short of saying people never should consume energy drinks, he says that mixing them with alcohol is dangerous and should be avoided. "The best analogy I can come up with is it's the same as driving a car, putting one foot on the gas and one foot on the brakes,” he says of combining the stimulants in caffeine and the intoxicating effects of alcohol.

When people consume these beverages before intensive exercise, he says, they should be aware of the effects the drinks have on people's bodies. They can put a strain on the body due to the caffeine and, in some of the beverages, other diuretics. These can cause dehydration or even collapse, particularly if people drink more than one can before exercising, he says.

Karam-Hage is particularly concerned about the popularity of the drinks among young people. The beverages can cause children to be hyperactive, fidgety or even rageful, he says.

MEDICA.de; Source: University of Michigan Health System