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.

Mary Altaffer / Associated Press (ENLARGE)

Ocean Spray recently launched Cranergy Energy Juice Drink, a low-calorie beverage that is sweetened with Splenda and caffeinated with green tea extract.

CAFFEINE COUNT • Arizona Green Tea Energy: 200 millgrams • Coffee: 77 mg • Crystal Light Energy: 120 milligrams • Enviga: 100 milligrams • Fix: 500 milligrams • Propel Invigorating Water: 50 milligrams • Red Bull: 80 milligrams • Rockstar Roasted: 225 milligrams • SoBe Essential Energy: 96 milligrams • Starbucks Grande Coffee: 330 milligrams • VitaminWater Energy Citrus: 42 milligrams Source: energyfiend.com Related health stories: • Back to health

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."

Ginseng and ginkgo balboa sound like healthy ingredients but there's no proof that they work. Like caffeine, they can stimulate the central nervous system. Jamba Juice's new 3G Charger boost gets its blast of energy from ginseng, the stimulant guarana and 120 mg of "natural" caffeine.

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. 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.

WHAT'S IN ENERGY DRINKS

• Caffeine: Side effects common for 200 millgrams or more.

• Taurine: Amino acid helps regulate heartbeat and muscle contractions.

• Guarana: Comes from South American plants. Increases alertness and energy.

• B vitamins: Convert sugar into energy.

• Ginseng: Herb known to increase energy.

• Ginkgo biloba: Helps memory, concentration and circulation.

• L-Carnitine: Amino acid increases metabolism.

• Sugars

• Antioxidants: Vitamins C and E help the body recover from damage caused by free radicals.

Source: energyfiend.com, drinkhealthydrinks.com