According to the American Council of Science and Health, 11 million Americans consume too much caffeine. Are you one of them?

Caffeine is consumed throughout the world in many forms, including coffee, lattes, tea, soft drinks and in cocoa products (chocolate candy, baked goods and hot cocoa). Everybody does it, so it sounds harmless, doesn't it?

Not really. It depends on how much caffeine you consume and how your individual body chemistry responds.

Caffeine is frequently the "drug of choice" on college campuses because it is a stimulant and has the ability to make you feel more alert.

Caffeine affects many parts of your body. It stimulates your brain, making you feel more awake, energetic and better able to concentrate. It stimulates your heartbeat, enables muscles to work better, increases acid production in your stomach and stimulates the kidneys to increase the production of urine.

It affects many blood vessels in the body, such as in the lungs and brain. This is why caffeine sometimes helps people with asthma and migraine headaches.

It speeds up the rate that your resting body burns energy, which is why caffeine is frequently found in diet pills. However, because the effect is short-lived, caffeine is not a good long-term diet aide.

Too much caffeine can cause over stimulation and result in restlessness, jumpiness, anxiety, difficulty sleeping, irregular heartbeat, twitching muscles, nausea and abdominal pain.

Individual reactions to caffeine vary widely. Some people may experience some of the above symptoms after a small amount of caffeine, while others can handle more caffeine without symptoms.

You can also develop caffeine tolerance. This means that you need increasing amounts of caffeine to get the desired effect.

If you are "caffeine-dependent," you can get withdrawal symptoms (tiredness, headache and irritability) if you reduce your consumption.

How much caffeine is OK? Moderate caffeine intake (less than 300 milligrams per day) is not associated with any health risk. Three 8-ounce cups of coffee (which is about 250 milligrams of caffeine) per day is considered an average or moderate amount of caffeine.

Remember that a sudden decrease in caffeine consumption can cause symptoms of caffeine dependence. To avoid these symptoms, you should reduce your consumption gradually.

Also, do not forget that many prescription and over-the-counter medications also contain caffeine.