Caffeine

What is caffeine?

Caffeine is a stimulant drug which makes the central nervous system (CNS) speed up the messages to and from the brain. It is a substance found in the leaves, seeds or fruit of a number of plants, such as coffee and tea plants. A wide range of food and drinks contain caffeine, including chocolate, soft drinks, energy drinks, tea and coffee. It can also be taken in capsules, tablets, or powder form.

Caffeine content

The approximate amount of caffeine found in coffee, tea, chocolate, cola, energy drinks, and caffeine tablets is as follows:

Product                        Caffeine content

Typical tablet                      100 mg
Cup of instant coffee*          60-80 mg
Cup of brewed coffee*         60-120 mg
Cup of black tea                  10-50 mg
Cola drink                           13 mg per 100 mL
Can of cola 375 mL              8 mg
Bottle of cola 600 mL            78 mg
Red Bull 250 mL                   80 mg
'V' 250 mL                             80 mg
Guarana tablet 1000 mg       40 mg
Cup of hot chocolate            5-10 mg

*amount of caffeine depends on the type of coffee bean and size of cup.

Effects of caffeine

The effects of caffeine differ from person to person, depending on your age, body size and general health. If you regularly have caffeine you might have different reactions than if you have caffeine only occasionally.

Short-term effects

Caffeine takes 5-30 minutes to circulate around the body. Physical effects of caffeine include increased heartbeat, respiration, basal metabolic rate, and increased stomach acid and urine.

Small to medium amounts of caffeine, up to 300mg, can speed up the brain and the central nervous system so that you feel more awake. It also increases your concentration and alertness. However, caffeine isn't a substitute for sleep.

Long-term effects

Research has shown that moderate caffeine consumption (up to 300mg) does not cause miscarriage, early delivery or low birth weight. As with any drug, if you are pregnant or nursing, check with your doctor. 

Some research has shown links between heavy use (ie greater that about 350mg or three cups per day) of caffeine and osteoporosis, high blood pressure and heart disease, heartburn, ulcers, severe insomnia and infertility. Some studies have shown that women who consume high amounts of caffeine have increased risk of miscarriage, difficult birth and delivery of low-weight babies.

Can you overdose on caffeine?

If you consume too much caffeine it is possible that you might have serious health consequences, or even die in extreme circumstances, but this is extremely rare. A person would have to consume 5-10 grams of caffeine (or 80 cups of strong coffee, one after the other) to have an overdose.

Caffeine addiction + withdrawal

Caffeine is addictive according to several definitions of 'addiction'. It causes withdrawal symptoms after you stop after having it regularly (most commonly headaches) and you can develop tolerance and experience cravings when you stop having it. Regular users can also become emotionally and mentally dependent upon their daily caffeine (coffee, energy drinks, etc). Withdrawal usually last for only a few days and is minimal if you reduce caffeine gradually.

Things to remember

Often caffeine pills or energy drinks such as No Doz or Red Bull are often taken by young people during exam or study periods in an effort to stay awake and alert to study more. Caffeine isn't a substitute for normal sleep patterns. So, at the end of a study period if a lot of caffeine has been used you may find you have didifculty sleeping or that you are moody and irritable. You may also experience headaches.

Caffeine is a drug and can affect any the effectiveness of drugs, so before taking any medication make sure you tell your doctor or pharmacist how much caffeine you take.