Energy Drinks

More than 500 new energy drinks launched worldwide in 2006 in a $3.4 billion-a-year industry (which grew by 80 percent in 2005).
The caffeine comes from multiple sources, making it hard to tell how much the drinks contain. Some have B vitamins, which when taken in megadoses can cause rapid heartbeat, and numbness and tingling in the hands and feet.
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Carol Ann Rinzler, author of "Nutrition for Dummies," examined the labels of the top three energy drinks. "The labels simply don't deliver all the facts," she said. "For example, while all list caffeine as an ingredient, and most tell you exactly how much caffeine is in the drink, they also list guarana, a caffeine source, as a separate ingredient but don't tell how much caffeine one gets from the guarana." Rinzler said energy drinks also deliver a huge hit of sugar. "Drink more than one and you get lots of sugar 14 teaspoons in two cans, 21 teaspoons in three," she said. Add in megadoses of some vitamins; unnecessary nutrients (taurine) and more caffeine than plain sodas and you get "a fast up-and-down sugar high and a really rough caffeine buzz," she said. "And drinking two or three cans a day for a period of weeks or months might trigger some side effects from the vitamin megadoses." Also see Table in Wiki, and a little bit about some ingredients.
While the Food and Drug Administration (FDA) allows companies to sell and market their energy drink products, there has been very little research that has been done on them.
Monster is produced by Corona, Calif.-based Hansen Natural Corp., and Rockstar, distributed by Coca-Cola Co., is made by Las Vegas-based Rockstar Inc.

ABC News/Live Science, Mr. Nice Guy, Energy Fiend, Wiki