Cans of energy drinks are displayed in a store in San Diego, California.
Cans of energy drinks are displayed in a store in San Diego, California. - 
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The Wall Street Journal this morning reports high-caffeine energy drinks are the latest target for investigators in New York. The state's attorney general has issued subpoenas to Monster Beverage, Pepsi -- which makes AMP -- and Living Essentials, which makes those little 5-Hour Energy shots. All three companies declined to comment on the story.

Americans are slamming these things back -- sales of energy drinks rose 16 percent last year. But New York officials suspect there's some false advertising going on.

Dr. Tod Cooperman recently conducted his own independent chemical analysis of some popular energy drinks for the site He says these products often don't tell you how much caffeine is really in them.

"You're getting a lot of caffeine from these products," Cooperman says. "But you're also getting high amounts of vitamins -- more than you really need. For example, maybe getting 40 to 200 times the amount of certain B vitamins that you require."

He also says taking too many of these products could be dangerous.

Get more details from the audio above.

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Follow Jeff Horwich at @jeffhorwich