Caffeine is a substance found naturally in the seeds, leaves and fruits of many plants. These include tea leaves, coffee beans and cocoa beans, which we consume when we drink tea and coffee or when we eat chocolate.
Although caffeine exists naturally in certain plants, it can also be produced synthetically and is used as an additive in food and drinks. Caffeine has no flavour and can be removed from a food by a chemical process called decaffeination.
It can also be found in over-the-counter medications such as pain killers, appetite suppressants and cold medicines.
How does it affect the body?
Caffeine is absorbed and distributed throughout the body very quickly. After absorption, it passes into the brain where it acts as a central nervous system stimulant. As it has diuretic properties, caffeine is not accumulated or stored in the body, but is excreted in the urine some hours after it has been consumed.
Contrary to popular belief, caffeine does not reduce the effects of alcohol, so a cup of coffee will not "sober up" someone who is drunk. Caffeine may be used as a treatment for migraine and will, for short time spans, relieve fatigue or drowsiness.
However, excessive caffeine intake can lead to a fast heart rate, increased urination, nausea, vomiting, restlessness, anxiety, depression, tremors, and difficulty sleeping.
