energy drinksWhat happened to 14-year-old Anais Fournier is both incredibly heartbreaking and incredibly scary: After drinking two 24-ounce Monster Energy Drinks at the mall one day with her friends, the teen went into cardiac arrest due to caffeine toxicity and died. Even scarier? Along with Fournier's tragic passing, the FDA is investigating four other deaths they believe could be related to Monster Energy Drinks. WHAT?! I mean, we all know that too much caffeine isn't good for anyone, kids in particular, but who knew it could be fatal? And how much caffeine is in this stuff, anyway?

Well, a lot. Especially for a 14-year-old: By drinking two 24-ounce cans, Fournier consumed roughly 480 milligrams of caffeine (the equivalent of drinking 14 cans of Coke). Adults are advised to keep their daily caffeine intake under 500 mg. Still, while caffeine toxicity, or poisoning, is surprisingly common, it's rarely fatal. So why are people dying?

There is no official answer as of yet, but in Fournier's case, it seems a common pre-existing heart condition called mitral valve prolapse could have put her at risk. Mitral valve prolapse causes one of the heart's valves to malfunction and affects between 1 and 20 Americans, but it doesn't usually cause any actual health problems.

Or at least mitral valve prolapse didn't usually cause actual health problems -- you know, back before energy drinks containing mass quantities of caffeine hit the shelves. More research needs to be done before a link is established, but if I had this particular physical issue (most people know whether or not they have mitral valve prolapse, as the condition is regularly detected at routine physicals), I would most definitely lay off the energy drinks for awhile.

Do you worry about the amount of caffeine in energy drinks?

Visit NBCNews.com for breaking news, world news, and news about the economy


Image via Mitchell Laurren-Ring/Flickr