Energy -- the high-octane kind that pumps up the most stressed-out bodies -- is only a sip away.

Or so goes the promise from the more than 500 energy beverages that are fueling fatigued consumers.

Some of the latest additions to this $3 billion business rely on healthy-sounding ingredients such as vitamin B and ginseng for that extra boost. The names say it best: Cranergy. Crystal Light Energy Wild Strawberry. Dansani Refresh and Revive. SoBe Essential Energy.

These fruit juice-spiked drinks are refreshing, but can they really deliver a healthy jolt of energy?

Here, five things everyone should know about this human rocket fuel:

1. The "boost" these drinks provide is not true energy.

Aggressive marketing and urban legends have fueled the popularity of these drinks, said Dr. Damon Schranz, an assistant professor at the University of North Texas Health Science Center. "Some people may actually believe they are health drinks."

But true energy comes from calories, not caffeine, said Lona Sandon, assistant professor of clinical nutrition at the University of Texas Southwestern Medical Center. Most of the drinks deliver lots of sugar, caffeine and other stimulants.

All that caffeine perks people up, makes their heart race and gives them a sense of feeling energized.

"But it's a false sense of energy and any central nervous system stimulation they get is going to be short-lived," Sandon said. "You could get the same feeling if you took a 10-minute brisk walk."

2. Fruit juice-based energy drinks aren't necessarily any healthier than a glass of OJ.

Cranergy "cranberry lift" is a new drink from Ocean Spray fortified with vitamin B and green tea extract.

"People see it and think cranberry juice is very healthy and when you throw in a little herbs then that must be even better," Sandon said. "But vitamin B does not create energy. It works by helping the body metabolize food."

3. Some energy drinks are loaded with sugar.

Arizona Green Tea Energy, SoBe Energy Citrus and Naked Juice Energy Smoothie contain more sugar than a can of Dr Pepper. Sucking down energizing waters or juices can add tons of sugar and about 150 calories.

4. Some can lead to tooth decay.

One health concern with many of the fizzy energy drinks is high acidity levels. Boulder-based Izze juice beverages have recently come out with a fortified version that has 70 percent fruit juice, no added sugar and 10 percent of the daily recommended values of vitamins C and B-6 and niacin. But the fizz in drinks can lead to tooth erosion, Schranz said.

5. For a few, some energy drinks might be dangerous.

Guarana, a common ingredient in energy drinks is a stimulant, but its effect lasts longer than caffeine. Too much may lead to abnormal heart rhythms, especially when combined with alcohol. People who have existing cardiac or seizure disorders should stay clear of these drinks, Schranz said. The stimulant in these drinks can also disrupt the sleep cycle.