True or false: A cup of Häagen-Dazs coffee ice cream has more caffeine than a can of Coke. Reward yourself with a spoonful of ice cream if you said "true."

We discovered that fact during a recent analysis of the caffeine content of 25 products. The results indicate that people, especially children, can easily consume enough caffeine to leave them jittery and anxious. And because foods and drinks are not required to list how much caffeine they contain, it can be hard to gauge how much you or your kids are getting. Some of the products we tested, such as iced teas and colas, are obvious caffeine carriers. But you might be surprised by the amount hidden in others:

• Mountain Dew has more caffeine than Coke or Pepsi; Sunkist Orange has nearly as much as the colas, though Minute Maid Orange has none.

• Trendy vitamin waters can harbor caffeine, too. Ounce for ounce, Glacéau Vitaminwater Energy Tropical Citrus has about twice as much caffeine as Nestea Iced Tea.

• A 9.5-fluid-ounce bottle of Starbucks Coffee Frappuccino, a sweet, milky drink, delivers almost as much caffeine as three 12-ounce cans of Coke.

• An 8.4-ounce can of the energy drink AMP has about three times as much caffeine as the same amount of SoBe Energy Citrus Flavored Beverage. Many energy drinks (and some fortified waters) also include guarana, a caffeine-containing herb, and ginseng, which may intensify caffeine’s effects.

In addition to our analysis of caffeine content, we held taste tests to see whether students preferred regular Coca-Cola Classic or Pepsi to their caffeine-free counterparts (see below).

Although thousands of studies of caffeine have been conducted, relatively few have involved youngsters. From what is known, caffeine seems to have the same effects on kids and teenagers as on adults. "At low doses, it produces an increase in wakefulness, alertness, feelings of energy, and sociability," says Roland Griffiths, a professor in the departments of psychiatry and neuroscience at the Johns Hopkins University. "As you increase the dose, you get into anxiety, insomnia, and tension. Raise it further and you get into things like nausea and upset stomach."

	TASTE TEST Manufacturers say that caffeine adds flavor. To test that claim, we had 56 students at a middle school near our headquarters, in Yonkers, N.Y., do blind taste tests of Coke and Pepsi versus their caffeine-free versions. There was no clear-cut preference; some kids actually liked the caffeine-free colas better. In similar tests a few years ago, most kids couldn’t differentiate between other brands of regular and caffeine-free soda.

Joan Carter Clark, a registered dietician and an instructor in the pediatrics department at Baylor College of Medicine, says, "Moderate amounts should not be a concern for most children, but your child may not be most children."

Indeed, the amount needed to produce adverse effects varies with body weight, tolerance built up through use, and innate sensitivity to caffeine. Some experts suggest upper limits for kids: no more than 100 milligrams per day, for example, which is about the amount in three cans of Coke.

That amount might not be hard to consume, even in a short time. A can of Mountain Dew, a cup of Starbucks Coffee Java Chip ice cream, and a half-cup of M&M’s have a total of 128 mg of caffeine. A dose of more than 4.5 mg per pound of body weight, or at least 180 mg for a 40-pound child, can cause nausea, vomiting, diarrhea, cramps, and muscle twitching.

The Canadian government makes caffeine recommendations by age: no more than 45 mg per day for 4- to 6-year-olds; 62.5 mg per day for 7- to 9-year-olds, and 85 mg per day for 10- to 12-year-olds. (For adults, 300 mg--the amount in 2 to 3 cups of brewed coffee--is considered a moderate intake.)

But the experts we consulted don’t find such limits useful. "There are just not enough data to go on," says John Hughes, M.D., a professor of psychiatry at the University of Vermont who has studied behavioral effects produced by caffeine.

In the absence of agreed-upon limits, it makes sense to minimize a child’s caffeine intake. That task would be far easier if amounts were shown on labels. Manufacturers must list caffeine among the ingredients only if they’ve added it; even then, they need not list the amount. Of the products we analyzed, only AMP Energy Drink says "not recommended for children."

In 1997 Griffiths, Hughes, and other researchers, along with the Center for Science in the Public Interest, a nonprofit nutrition-advocacy group, petitioned the U.S. Food and Drug Administration to require that labels specify caffeine amounts. Their petitions are still under review.

Since the amount of caffeine is not labeled, it’s easy to consume a lot without knowing it. Just check out the numbers below, taken from our analysis. The "surprise" photos show products whose caffeine content might be unexpected. We’ve standardized drink sizes for easy comparison, but be aware that these sizes are modest and are often less than the full container. (The smallest soda can, for instance, generally holds 12 fluid ounces.) And hardly anyone stops at a half-cup of ice cream, even though that’s the federal government’s official serving size.

Sodas
	SURPRISE Sunkist Orange Soda, 23 mg per 8 fl. oz.

With caffeine	Caffeine, 8 fl. oz.
Red Fusion	38 mg
Mountain Dew	37
dnL	27
Pepsi	27
Pepsi Blue Berry Cola Fusion	26
Coca-Cola Classic	24
Vanilla Coke	21
Barq's Famous Olde Tyme Root Beer	15
Caffeine-free
Minute Maid Orange, Slice, Sprite, 7-Up, Mug Root Beer. No-caffeine versions of Mountain Dew, Barq's, and other sodas.

Other drinks
	SURPRISE Glacéau Vitaminwater Energy Tropical Citrus (C+ginseng), 21 mg per 8 fl. oz.

With caffeine	Caffeine, 8 fl. oz.
Starbucks Coffee Frappuccino	83 mg
AMP Energy Drink	77
Red Bull Energy Drink	70
Elements Atomic Jacked Apple Juice Drink	33
SoBe Energy Citrus Flavored Beverage	25
Snapple Lemon Iced Tea	19
Nestea Iced Tea Sweetened Lemon	10
Nestle Carnation Rich Chocolate Flavor Hot Cocoa Mix	2
Caffeine-free
Herbal iced tea, lemonade, fruit juice, milk, tap or plain bottled water.

Snacks
	SURPRISE Dannon Natural Flavors Low Fat Coffee Flavored Yogurt, 6-oz. container, 36 mg.

With caffeine	Caffeine
Starbucks Coffee Java Chip Ice Cream, 1/2 cup	28 mg
Häagen-Dazs Coffee Ice Cream, 1/2 cup	24
M&M's Milk Chocolate Candies, 1/4 cup	8
Hershey's Kisses Milk Chocolate, 9 pieces	5
Hershey's Syrup Genuine Chocolate Flavor, 2 tbsp.	5
Breyers All Natural Chocolate Ice Cream, 1/2 cup	3
Reformulated recently. New version unavailable in time for testing.
Caffeine-free
Candies without chocolate. Any ice cream, sorbet, sherbet, or yogurt without coffee or chocolate.