by Stephen Janowsky

Created on: July 17, 2008

Coffee has been consumed for centuries, in spite of repeated attempts to prohibit its use for moral, economic, medical or political reasons. It was discovered in the 9th century in Arabia and it was cultivated for the first time in Ethiopia. In the 15th century, the technique of toasting and grinding coffee grains was developed and the consumption of coffee quickly expanded worldwide.

Coffee is the dried mature seed of Coffea arabica. It is the product that contains the highest amount of caffeine in the diet (0.8-1.8%). The dose of caffeine in coffee depends on genetic differences between grains, as well as on the time and the form of preparation, varying between 30 and 175 mgs by 150 ml. Decaffeinated coffee contains between 2 and 8 mgs by 150 ml. Caffeine, as well as theobromine and theophylline, is a methyl-derivative of xanthine, which is itself a purine-derivative. It is included in the pharmacological group of psychostimulants.

Coffee intake has many effects on various organs and systems:
- Central nervous system. Caffeine induces a generalized activation of the central nervous system, in a dose-dependant manner, possibly by enhancing the release of noradrenaline. It increases the alert, reduces the sensation of fatigue, it stimulates the capacity to maintain intellectual effort, and maintains the state of wakefulness in spite of sleep deprivation. In addition, caffeine has an invigorating action by means of dopamine release in the limbic system. Caffeine also has an analgesic effect, being sometimes used as an adjuvant in analgesia. It produces blood vessel constriction in the brain, which makes it an effective treatment for migraine. On the other hand, caffeine abuse can cause anxiety, panic attacks, nightmares, and dependency.
- Respiratory system. Methyl-xanthines, especially theophylline, stimulate the respiratory nervous center, dilate the airways, and slightly improve the respiratory function, by increasing the force of contraction of the diaphragm muscle. Therefore, these substances are useful in asthma and other chronic or acute respiratory diseases. They are also first choice drugs in the treatment of apnea in the premature newborn.
- Cardiovascular. Caffeine administration increases the arterial pressure, the heart rate and the heart pumping capacity. However, caffeine ingestion has not been directly linked to hypertension risk, and it does not induce rhythm disturbances, except at very high doses. Most large prospective cohort studies have not

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