Caffeine

Caffeine is an alkaloid found naturally in such foods as coffee beans, tea, cacao beans (chocolate), kola nuts, and guarana. It is well known as a stimulant of the central nervous system, heart, and respiration. It is also a diuretic. It is sometimes added to soft drinks such as cola.

Caffeine, C₈H₁₀N₄O₂, or 1,3,7-trimethylxanthine or 3,7-Dihydro-1,3,7-trimethyl-1H-purine-2,6-dione, is an alkaloid of the methylxanthine family, which also includes the similar compunds theophylline and theobromine. In its pure state it is an intensely bitter white powder.

A typical cup of drip-brewed coffee contains 100 to 200 mg of caffeine. A single shot (1 - 1.5 oz.) of espresso contains about 100mg. Stimulant pills may contain as much as 200 mg each. The LD₅₀ is estimated to be about 10 grams, the equivalent of about 50 cups of coffee.

Continued consumption of caffeine can lead to tolerance. Upon withdrawal, the body becomes oversensitive to adenosine, causing blood pressure to drop dramatically, leading to headache and other symptoms. Recent studies suggest that caffeine intake (in coffee) may decrease the risk of developing Parkinson's disease (http://www.parkinson.org/coffee.htm), but additional study is needed.

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