New York officials are at it again. On the heels of Mayor Michael Bloomberg's proposed ban on large sugary drinks, the state's attorney general has reportedly subpoenaed three leading major energy drink companies, seeking information about their labeling and advertising practices.

Last month, Eric Schneiderman issued subpoenas to Monster Beverage Corp. , PepsiCo Inc., which produces AMP, and Living Essentials LLC, maker of 5-Hour Energy drink, according to an unnamed source cited by the Wall Street Journal. The investigation is said to focus on claims that the companies are misleading consumers by understating the amount of caffeine in their products, while exaggerating the benefits of exotic ingredients such as guarana.

The energy drink industry is growing fast: U.S. sales of the products were up 16 percent last year, according to Beverage Digest statistics. But industry critics say the Food and Drug Administration cannot regulate the beverages as it would traditional sodas, because “energy drinks” are not well-defined under agency regulations.

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