Consumers need to know risks of energy drinks, study says

Energy drinks can have 10 times or more caffeine as soft drinks, prompting Johns Hopkins University scientists to recommend the drinks carry labels with caffeine content and warnings about the health risks.

Energy drinks are sold as dietary supplements, and the FDA doesn't regulate their caffeine levels or require warnings. A typical 12-ounce soft drink includes about 35 milligrams of caffeine, and some energy drinks have as much as 500 milligrams, researchers said. Consumers may be unaware of caffeine levels and potential risks, the report said.

"If you are going to use a drug, you should know what it is, what it does and how to use it effectively," said Roland Griffiths, a professor of behavioral biology at Johns Hopkins University. "If you don't label that, you don't know that."

Caffeine intoxication can lead to nervousness, anxiety, restlessness, insomnia, gastrointestinal upset, tremors, rapid heartbeat and overdose, Griffiths said.

Americans spent about $5.4 billion on energy drinks in 2006, an amount growing about 47 percent a year, the report said. The drinks are promoted as performance enhancers and aimed at young people.

The Hopkins researchers, who have spent decades researching the effects of caffeine, listed the caffeine content of numerous energy drinks in the report. Such top-sellers as Red Bull had 80 milligrams of caffeine per drink, compared with 35 milligrams in a Coca-Cola Classic. Rockstar, another top seller, had 160 milligrams and No Fear had 174 milligrams. At the high end, Wired X505 had 505 milligrams per drink and Fixx had 500 milligrams.