At first, it used to be easy to pick an energy drink alternative because there was only one: Red Bull. But in the last few years, the market has exploded, and befittingly so, since people of all ages are gulping them down in shots to stay energized. It's hard to keep those predominantly tall, narrow cans plastered with exclamation points straight, so Maxine Kaplan, a college student with a caffeine addiction, taste tests five popular drinks on the market now: Arizona Green Tea Energy, Monster, Red Bull, Rock Star, and Tab Energy. She judged how they tasted, and let others test the energy. Tab seems to have come out the overall winner.

Arizona Low-Carb Diet Energy Drink

• Claims to be a "caffeinated 'herbal cocktail' [that] energizes and heals with its combination ginseng, milk thistle, taurine, and vitamins A, B and C."
• Taste - "Not fab, but not bad"
• Energy - "doesn't provide you the quick jolt you need to get through a long day." Rated a 3.

Lo-Carb Monster Energy Drink

• "energy blend that also includes glucose, caffeine, guarana and inositol" as well l-carnitine
• Taste - "very drinkable"
• Energy - "worked almost too well and she was unable to settle down or, later that night, sleep." Rated 2.5

Red Bull Sugar-Free

• Claims "high concentration of taurine and also contains glucuronoclatone (a naturally occurring carbohydrate) and caffeine."
• Taste - "resulted in instant nausea"
• Energy - "3 for it's initial boost and a 1 for the swift comedown."

Rock-Star Double-Strength Diet Energy Drink

• "a treasure trove of chemicals"
• Taste - "I was drinking: yellow Triaminic"
• Energy - "got a little stomach ache but I did feel quite a bit speedier." Rated 3.

Tab Energy

• "taurine is its main energizing component"
• Taste - "the one I'm most likely to drink again"
• Energy - "it gave me a huge boost." Rated a 4.

Monster, Red Bull, an Rock Star were also recently taste tested by the Mercury News.