Energy drinks: behind the buzz.(Product/service evaluation)

You drink them cold, but energy drinks are hot. U.S. conAsumers spent $744 million on those caffeinated beverages during the year ending June 17, 2007, a 34 percent increase over the previous year, says Information Resources, a market-research firm. With names like Rockstar, Full Throttle, and No Fear, they may appeal especially to young adults.

"Energy drink" sounds healthful, but most contain multiple stimulants, making them a poor choice for young children and Archer Farms pregnant women; and they can be risky if mixed with alcohol. We think the governAment should require companies to label caffeine content, but it doesn't, so you ofAten have no idea how much you're getting.

[ILLUSTRATION OMITTED]

Our experts tested 12 carbonated energy drinks (9 regular and 3 low-calorie) for caffeine content and taste.

What we found. Caffeine levels per 8-ounce serving ranged from 50 milAligrams to 145 mg. By comparison, a cup of coffee has roughly 100 mg; a 12-ounce Coke, about 24 mg. Caffeine intake up to about 300 mg a day is considered OK for most adults; children should be limited to well under 100 mg. But most tested enAergy drinks have more than 8 ounces per can or bottle. Anyone who guzzles the whole container consumes up to 200 mg of caffeine and up to 260 calories.

All the drinks tasted sweet, and many were a bit bitter. Sugar-free versions of Full Throttle, Red Bull, Rockstar, and Sobe had an artificial-sweetener flavor.

Most of the drinks list at least one stimAulant ingredient. Green tea and guarana supply caffeine, as does yerba mate, found in Steaz. Ginseng might amplify caffeine's effects. Other ingredients include taurine which some studies suggest improves mental performance, and glucoronolac-tone, which might yield a temporary "sugar buzz." Celsius and Enviga claim to burn calories, and in a few manufacturer-funded studies, healthy adults worked off about 100 calories more on average after drinkAing them than after drinking a placebo. (Connecticut's attorney general has asked Enviga for proof.) Other claims can be nonsensical. Red Bull says it "improves performance, especially during times ...