Five Common Caffeine Myths Busted

Aug. 11, 2008 — -- It's one of the oldest drugs on the market that's readily available and very addictive: caffeine. But conflicting information about caffeine abounds. "Good Morning America" medical contributor Dr. Marie Savard busted five common caffeine myths.

True or False?

1. Caffeine dehydrates you.

False

Savard says for caffeine to cause you to lose excess salt and urine, you'd have to take a lot. It would have to be within a short period of time. If you have a cup of coffee, it's not going to send you to the bathroom faster than anything else. It can count toward your hydration for the day, just like water.

2. Caffeine causes heart disease.

False

Savard says it's not going to cause a heart problem, but it is a stimulant, so it will stimulate your heart. If you already have an overstimulated heart from disease, it will exacerbate symptoms. But it won't cause the problem.

3. Caffeine helps weight loss.

False

It would take 35 cups of coffee to lose one pound a day. Caffeine can speed up metabolism, with 100 mgs of it helping to burn an extra 75 to 100 calories a day, but there has been no long-term benefit to weight control demonstrated.

In fact, in a study of more than 58,000 health professionals who were followed for 12 years, both men and women who increased their caffeine consumption gained more weight than those who didn't.

4. Caffeine helps you exercise.

True

A New York Times article reported that caffeine enhances endurance in aerobic activities, as well as performance in anaerobic ones. Some experts believe that it does so because it blunts the perception of pain and aids the ability to burn fat for fuel instead of its carbohydrates.

5. Caffeine is safe during pregnancy.

False

Savard stresses that even a 100 mg dose can be dangerous. According to a Kaiser Family Foundation study done earlier this year, caffeine is linked to increased risk of miscarriage.

Here are some caffeine figures:

Coffees:

Decaffeinated coffee or tea: 8 oz. 2 mg

Plain coffee, brewed: 8 oz. 95 mg

Dunkin' Donuts coffee: 12 oz. 154 mg

Starbucks coffee (tall): 12 oz. 195 mg

Teas:

Black tea, brewed: 8 oz. 47 mg

Green tea, brewed: 8 oz. 30 to 50 mg

Soft Drinks:

Soft drinks have a third to a half the caffeine that a cup of coffee will have, but energy drinks can have way more. One surprise here? A can of Red Bull only has 76 mg, so you'd actually do better having a cup of coffee.

Coca-cola Classic: 12 oz. 34 mg

Diet Coke: 12 oz. 46 mg

Mountain Dew: 12 oz. 54 mg

Red Bull: 8.3 oz. 76 mg

Monster Energy: 16 oz. 160 mg

Sobe No Fear: 16 oz. 174 mg

Food:

You might be surprised at how little caffeine is actually in chocolate. People think chocolate has a lot, but in this Hershey's milk chocolate, there are only 10 mg of caffeine. Coffee yogurt has 30 mg, a lot more than you might think. And Starbucks coffee ice cream has about the same amount in half a cup, or one serving.

Hershey's chocolate milk: 8 oz. 5 mg

Hershey's milk chocolate: 1.5 oz. 10 mg

Dannon coffee yogurt: 6 oz. 30 mg

Nodoz maximum strength: 1 tablet 200 mg (same as 2 cups of coffee)

Starbucks classic coffee ice cream: ½ cup 33 mg

Edy's Slow Churned coffee ice cream: 4 oz (about a scoop) 15mg