Friday, October 29, 2004
Cup of tea
What is it?
Caffeine is the most popular and widely used drug in the world. It is a substance found in the leaves, seeds or fruit of a number of plant species, such as coffee and tea plants.

Caffeine is a stimulant which acts on the central nervous system to speed up the messages to and from the brain. Its chemical name is 3,7-dihydro-1,3,7-trimethyl-1H-purine-2,6-dione (or 1,3,7-trimethylxanthyine for short).

What are the plants and where do they grow?

  • Coffee
    Coffee beans are the seeds of the coffee plants Coffea arabica, Coffea canephora and Coffea liberica. After oil, coffee is the world's second most traded product, with the two largest export growers being Brazil and Colombia.
  • Tea
    Tea is usually the leaves and buds of the tea plant (Camelia sinensis). The biggest producers of tea for the world market are India, China, Kenya and Sri Lanka.
  • Kola nut
    The seed of the kola nut (Cola acuminata and Cola nitida) is consumed as a nut or as a tea, and is grown in West Africa.
  • Cacao pod
    The seed of the cacao pod (Theobroma cacao) is used to make cocoa and chocolate products. It grows in Brazil and West Africa.
  • Guarana paste
    The seed of the guarana plant (Paulinia cupana), which is grown in Brazil, is used in snack bars and beverages.

Who uses caffeine in Australia?
Caffeine consumption is a part of everyday life in Australia. People have tea or coffee for breakfast, with meals or as a break for morning or afternoon tea. With our growing "café culture" many city people arrange social time together around meeting for a coffee. Children and adults consume caffeine through eating chocolate and drinking cola and energy drinks.

In 2003, the average Australian consumed 2.8 kilograms of coffee each year, which is not very high among coffee-drinking nations. However, we consumed about 5.8 kilograms of chocolate a year, ranking us seventh in the world.

In recent years, the increase in consumption of energy drinks containing caffeine has led to concern by teachers and parents of the possible effects of caffeine on children.

What are the effects of caffeine?
The effects of caffeine differ from person to person, depending on their age, body size and general health. Regular caffeine users may have different experiences from people who consume caffeine products only occasionally.

Short-term effects of caffeine
Caffeine takes 5–30 minutes to circulate in the body after it has been consumed. Its effects will continue as long as it is in the blood, which is usually around 12 hours.

Relatively small amounts of caffeine, such as one or two cups of coffee a day, can stimulate the brain and the central nervous system so that the person feels more aware and active. This level of consumption usually does not cause any lasting damage.

Some people consume drinks containing caffeine so that they can continue working or studying at night. However, the after-effect is that they will feel tired and lethargic the next day.

Use of caffeine can have a number of disturbing physical effects on some people, such as anxiety, irritability, increased breathing and heart rates, restlessness, excitability, dizziness, headaches, lack of concentration, gastro-intestinal pains, dehydration and the need to make frequent trips to the toilet.

Children and young people who consume energy drinks containing caffeine may suffer from sleep problems, bed-wetting and anxiety.

Caffeine overdose
Serious injury or death from caffeine overdose can occur, but is extremely rare. A person would have to consume 5 to 10 grams of caffeine (or 80 cups of strong coffee, one after the other) to suffer an overdose. Some effects of caffeine poisoning include involuntary shaking (tremors), nausea, vomiting, irregular or rapid heart rate, panic attack and confusion. An extreme case would be if a person became delirious or had a seizure. Seizure can result in them being unable to breathe, causing death.

In small children, caffeine poisoning can be seen with much smaller doses, such as up to one gram of caffeine (equal to around 12 energy drinks).

Long-term effects of caffeine
Moderate consumption (for example, up to four cups of coffee a day) of caffeine is unlikely to cause any long-term damage. However, heavier use of caffeine can have some serious effects.

Research has shown links between heavy use of caffeine and osteoporosis, high blood pressure and heart disease, heartburn, ulcers, severe insomnia and infertility. Pregnant women who consume high amounts of caffeine have increased risk of miscarriage, difficult birth and delivery of low-weight babies.

The major behavioural problems associated with heavy caffeine use are anxiety and depression.

Is caffeine addictive?
With regular use, over time a person's body can become used to functioning with caffeine present. They may become physically or psychologically dependent, or both, on caffeine. There are degrees of dependency, from mild dependency to compulsive use (addiction).

A person who uses caffeine in small to moderate doses will experience little or no harm. However, experts say that as little as 350 milligrams of caffeine a day (equal to about four energy drinks or four cups of medium to strong coffee) is enough to cause dependence. A person who is dependent on caffeine is likely to suffer withdrawal symptoms if they try to stop using it.

Withdrawal symptoms
A person who is dependent on caffeine is likely to suffer withdrawal symptoms within 24 hours of their last dose. Heavier users who consume more than 600 milligrams of caffeine a day may experience these symptoms within six hours.

Headache is the most common caffeine withdrawal symptom, but others include fatigue, sweating and muscle pains. Some users experience anxiety and tension when they give up caffeine. Withdrawal symptoms typically last around 36 hours, but very heavy caffeine users can experience withdrawal symptoms for longer.

Need help with your caffeine intake?
If you (or someone you know) are experiencing problems or would like advice on your caffeine intake, consult your doctor or other health professional.

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