Caffeine can cause a dangerous spike in blood pressure, even if you only reach for an energy drink occasionally

Corbis Images

Whether it's after a late night of partying or before clocking extra-long hours at the office, we all need a little energy boost from time to time. And if you reach for an energy drink, you might justify it by saying it's fine, because you never do that. Sure, you're aware of the concern over their potential negative effects, but that's only for people who down one every day...right? (Always Tired? Sleep Apnea Could Be to Blame.)

Well, if you're not a regular energy drink user (or coffee addict, or regular consumer of any other source of caffeine), you're what researchers call "caffeine naïve." Your body isn't used to the stimulant, and a new study found that that may make energy drinks more dangerous for you-even if you're young and healthy.

Researchers at the Mayo Clinic, who presented their findings last weekend at the American College of Cardiology's annual conference, gave an energy drink or a placebo drink to healthy young adults between 19 and 40 with normal blood pressure. The next day, they gave them the other liquid. The researchers then looked at the differences in blood pressure and heart rate for both days, and also compared how regular caffeine users (those consuming 160 mg or more of caffeine-the amount in a cup of coffee-each day) and those who were "caffeine naïve" responded.

After drinking the energy drink, the study participants' blood pressure readings went up. And if they were in the group that didn't regularly use caffeine, that spike was even sharper. That's a concern, since spikes in BP can put stress on your heart and can even make you feel anxious.

But what's a gal to do with that 2 o'clock craving? Ditch the drink and try one of these 8 Energy Boosters to Avoid a Mid-Afternoon Slump instead.