Caffeine....

Caffeine is a bitter substance found in coffee, tea, soft drinks, chocolate, some nuts and certain medicines. It has many effects on the body's metabolism, including stimulating the central nervous system. This can make you more alert and give you a boost of energy.
For most people, the amount of caffeine in two to four cups of coffee a day is not harmful. However, too much caffeine can make you restless, anxious and irritable. It may also keep you from sleepingwell and cause headaches, abnormal heart rhythms or other problems. If you stop using caffeine, you could get withdrawal symptoms.
Caffeine is a drug that is naturally produced in the leaves and seeds of many plants. It's also produced artificially and added to certain foods. Caffeine is defined as a drug because it stimulates the central nervous system, causing increased alertness. Caffeine gives most people a temporary energy boost and elevates mood.
Caffeine is in tea, coffee, chocolate, many soft drinks, and pain relievers and other over-the-counter medications. In its natural form, caffeine tastes very bitter. But most caffeinated drinks have gone through enough processing to camouflage the bitter taste.
Teens usually get most of their caffeine from soft drinks and energy drinks. (In addition to caffeine, these also can have added sugar and artificial flavors.) Caffeine is not stored in the body, but you may feel its effects for up to 6 hours.

Caffeine sensitivity (the amount of caffeine that will produce an effect in someone) varies from person to person. On average, the smaller the person, the less caffeine needed to produce side effects. Caffeine sensitivity is most affected by the amount of caffeine a person has daily. People who regularly take in a lot of caffeine soon develop less sensitivity to it. This means they may need more caffeine to achieve the same effects.
Caffeine is a diuretic, meaning it causes a person to urinate (pee) more. It's not clear whether this causes dehydration or not. To be safe, it's probably a good idea to stay away from too much caffeine in hot weather, during long workouts, or in other situations where you might sweat a lot.
Caffeine may also cause the body to lose calcium, and that can lead to bone loss over time. Drinking caffeine-containing soft drinks and coffee instead of milk can have an even greater impact on bone density and the risk of developing osteoporosis.
Caffeine can aggravate certain heart problems. It may also interact with some medications or supplements. If you are stressed or anxious, caffeine can make these feelings worse. Although caffeine is sometimes used to treat migraine headaches, it can make headaches worse for some people.

In the Coca Cola, have 34 mg caffeine. Diet Coke 45 mg, Pepsi 38 mg, 7 up 0 mg (wow), milk chocolate 6 mg, ice tea 70 mg (ummmmzzzz....)



(for the variety source)