You may not realize this, but most energy drinks have just as much sugar as soda: A 12-ounce can of Red Bull and a 12-ounce can of cola both have about 9 teaspoons. So they're even on that score, but the smallest can of Red Bull also has 80 mg of caffeine, which is double what's in a can of Coke. And it may do a lot more than perk you up: A 2006 New Zealand study revealed that caffeine combined with the sugar in that Red Bull may temporarily inhibit the body's ability to burn fat. More alarmingly, since 2009, 5-Hour Energy (which is sugar-free, but has about 215 mg of caffeine) has been mentioned in 90 filings with the U.S. Food and Drug Administration, including more than 30 that involved serious or life-threatening injuries, reports The New York Times. While it's true that most people can handle one regular-size can without ill effects, the high levels of caffeine involved in multiple servings could result in dangerous, even life-threatening, effects on blood pressure, heart rate and brain function, according to a 2010 review in the The Mayo Clinic Proceedings. Most energy drinks also contain special ingredients that are said to boost physical or cognitive performance, like taurine (Red Bull), ginseng (Monster), and glucuronolactone (5-Hour Energy). But two researchers who conducted a review of these ingredients' effects concluded that there isn't much evidence that any of these will make you faster, smarter, or better in any way.
Best advice: Energy drinks will rev your engine more than soda, but there are safer ways to wake up.
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