Caffeine ( Coffee Poison )

Don't drink, smoke, or do drugs? Think you've got no vices? Think again. If you drink coffee, tea, cola or indulge in the occasional piece of chocolate, then you're using a drug. Believe it or not, caffeine has the same pharmacological effects on the body as many of the substances we associate with doing harm. Of course, coffee is so well integrated into our culinary culture that we barely give its health effects a second thought.

Apart from being highly addictive and causing unpleasant withdrawal symptoms if we stop drinking it suddenly, research shows that even a little bit of coffee may reduce fertility by damaging sperm. It's also bad news if you're pregnant. Caffeine seems to affect the amount of time the baby spends resting, which could lead to abnormal behaviour later on.

But every cloud has a silver lining. Ironically, caffeine is being administered to pre-term babies to help them breathe. It also appears to increase alertness and improve performance under some circumstances.

To drink or not to drink? That is the question . . .



1. Caffeine Consumption

Global consumption has been estimated to be 120,000 tonnes per annum. This is the approximate equivalent of one caffeine-containing beverage per day for each of the planet's 5 billion plus inhabitants. So, caffeine is almost certainly the most widely consumed psycho-active substance in the world.

As a beverage the worldwide consumption of tea is surpassed only by water.



2. Where Did Caffeine Come From?

The coffee "tree" is indigenous to Ethiopia, but its cultivation and use as a beverage stem largely from Arabia. In Arabic it was referred to as gahwah, the poetic term for wine. The Turkish equivalent is kahveh, which became cafe in French and kaffee in German.

Apparently the Ethiopians mixed crushed dried coffee beans with fat which they rolled into balls and used as food on journeys. By the early 16th century the beverage made from infusing ground roasted beans was well-established in the Islamic world, although a fundamentalist element felt that coffee was an intoxicant and it was banned for a time in several places.

Coffee shops sprang up throughout Europe - coffee was the fashionable drug of the 17th and 18th centuries; its delights, and the cravings for it, were the subject of J.S. Bach's "The Coffee Cantata".

The British were the first to tax coffee; in 1660 a duty of 4 pence per gallon was imposed. The popularity of coffee lead to anti-coffee petitions such as "What a curse it is that ordinary working men should sit the whole day in coffee houses simply to chatter about politics, while their unhappy children are wailing at home for lack of bread!"

It's been suggested that America owes its present day coffee habits to the famous Boston "tea-party" of 1773. As a protest against oppression and excessive taxes, citizens of Boston boarded British ships moored in the Harbour and tipped their cargoes of tea overboard. Since that time, the United States has become the major coffee-consuming nation of the world.



3. How Much Caffeine Is In Different Beverages And Food?

It's usually presumed that a regular cup of coffee contains 100mg of caffeine but it may range between 40 and 176 mg and the mean is closer to 85mg. There's probably less caffeine in a cup of tea - one study showed a median of 27mg per cup with a range of 8 to 91 mg. An ounce of sweet chocolate may contain between 75 and 150mg of combined methylxanthines and a cup of chocolate or chocolate milk may contain 150-300mg.

The principal dietary sources of caffeine are overwhelmingly coffee and tea. Coffee accounts for some 54 per cent of ingested caffeine, while tea accounts for some 43 per cent. The remaining 3% consists mostly of caffeine ingested in the form of cocoa and chocolate products, various fabricated soft drinks and mate (a tea drunk especially in South America).

In Australia a 375ml can of Coca Cola and Pepsi Cola contains about 40mg of caffeine. Regulations allow a maximum of 145mg of caffeine per kilogram of cola-type drink (54.5mg per 375ml can). "Jolt" Cola - said to have "twice the caffeine" - actually contains the permissible legal limit of around 54mg per bottle.

In the USA, the permissible limit of caffeine in cola drinks and other carbonated beverages is 200mg per litre. The US drinks also have higher levels of sugar. Caffeine's bitter taste acts as a flavouring agent to counteract the sweetness of the sugar.



4. What Caffeine Gets Up To In The Body

Caffeine is absorbed rapidly into the bloodstream from the gastro-intestinal tract. It reaches maximum concentration within about an one hour. The blood distributes it throughout the body. It even manages to pass through the blood-brain barrier.

The half life of caffeine in the human body varies between 3 to 7 hours. Throughout the body it increases metabolic rate by around 10%. Females metabolise caffeine 20-30% more quickly than males. However, it will take women on "the pill" twice as long to metabolise caffeine as women who are ovulating.

Early experiments showed that low concentrations of caffeine may produce small decreases in heart rate, whereas higher concentrations may make the heart beat abnormally fast.

In the brain it constricts the cerebral blood vessels. If you're used to drinking several cups of coffee a day but then you quit, those blood vessels will dilate, maybe enough to give you a powerful headache. It's one of the best known withdrawal symptoms.

Many people know that caffeine is a strong diuretic - it makes you urinate more than usual. Apparently this is due to increasing the blood flow through the kidneys.

It can produce insomnia - delaying the onset of sleep and reducing total sleeping time. It has a small effect on respiration by increasing blood flow through the lungs and increasing the supply of air by relaxing bronchiolar and alveolar smooth muscle. That's why it's proving effective in treating the breathing problems of some prematurely born infants.

Some people experience tremors after drinking coffee and tea. That's thought to be due to over-activation of the central nervous system.



5. Sobering Thoughts About Caffeine

"And I'd better have a big cup of extra strong black coffee to get me past the breathalyser."

Unfortunately, this is one of the most enduring myths about caffeine. True, it may manage to puncture that aura of numbness and make you feel a little sharper but it's no better at sobering you up and lowering your blood alcohol level than a glass of water.

On the other hand caffeine is a good friend the morning after. Alcohol can give you a thumping headache by enlarging cranial blood vessels. Caffeine constricts them and so may bring some relief from the hangover blues. That's why it's an ingredient in some over-the-counter pain killers.



6. How Caffeine Disturbs Your Sleep

If you value a good night's sleep then tea or coffee at bedtime probably isn't a good idea. Caffeine lengthens the time it takes to fall asleep, reducing your total sleeping time. But almost unique among drugs, it doesn't alter the normal stages of sleep. That's why it's better to use caffeine to stay awake than other substances like speed.



7. Caffeine, Conception and Babies

One recent report from the US revealed that women who drink in excess of one cup of coffee every day are only half as likely to conceive as those who drink less than a cup a day.

The odds are considerably worse if women drink more than two and a half cups a day. Then they are nearly 5 times less likely to conceive as women who drink no coffee at all.

Because there's not been as much research on caffeine as there has on nicotine and alcohol, this drug's effects on human development are not yet known. However a number of studies have shown that as little as 2 or 3 cups of brewed coffee every day during pregnancy can result in lowered infant birthweight.

Other studies have claimed that caffeine consumption during pregnancy is associated with prematurity, poorer reflexes and neuromuscular development.

It also appears that heavy caffeine use can affect a newborn baby.

When doctors ask mothers if they have been taking drugs they will think of drugs like heroin but they will not necessarily think of caffeine - it's a social drink, not a drug to them. Because caffeine is so widely used many people drink quite large quantities and don't realise that they have taken something potentially harmful to the baby. And this doesn't apply just to coffee and tea. Some pregnant women drink large amounts of cola beverages which also contain significant levels of caffeine.

Caffeine gets across the placenta very easily and if the mother continues to ingest her coffee or caffeine-containing beverage the foetus will end up having as much caffeine as the mother. If the mother stops drinking then within 24 hours the foetus may experience withdrawal symptoms. The same thing may happen immediately after birth when the baby is suddenly cut off from the maternal supply of caffeine, although it should be pointed out that this isn't common. The withdrawal from caffeine has been described as similar to what is seen in babies born to heroin addicts. These babies will cry, they don't sleep, they are agitated and restless, they wriggle and abrade the skin on their hands and knees, and they sweat.

There's a suggestion that such withdrawal "dysfunction" may be a contributing factor in infant disorders like neonatal apnoea (where the baby "forgets" to breathe properly) and sudden infant death syndrome. (For further information see "A Guide to Reproduction: Social Issues And Human Concerns" by Dr Irina Pollard, Cambridge University Press, 1994).



8. Caffeine And Muscle Fatigue

A Canadian researcher, Prof Howard Green, has carried out experiments looking at the role of caffeine in helping to overcome muscle fatigue in the quadraceps (thigh) muscles.

Green is from the University of Waterloo and in 1995 visited Cumberland College, part of the University of Sydney's Faculty of Health Sciences.

In his Canadian experiments, muscle fatigue was induced electrically and then caffeine tablets were taken which were the equivalent of 8-10 cups of coffee. Within an hour the effect of reducing fatigue could be noticed. It probably does this by making more calcium available to the muscles.

Professor Green cautions that his experiment only showed effects of caffeine after fatigue. He doesn't know what happens if you take it before exercising - whether or not it might help prevent muscle fatigue. That's a question he hopes to answer soon.

In whole body exercise caffeine can increase the performance of muscles. The theory is that it does this by making more fatty acids available to the muscles than usual and that delays depletion of glygocen reserves. It's known that depletion of glycogen from the muscles is tied in with fatigue. This kind of benefit should be relevant to endurance events such as running and cycling. But you may need to drink the equivalent of 8/9 cups of coffee to feel the effect!!



9. Does Caffeine Make You Mentally More Alert?

Too much caffeine may not be good for complex reasoning tasks, but it can improve mental speed-related tasks. These are some of the results of research by Dr Paula Mitchell, now working at the Alfred Hospital in Melbourne.

In 1989 Paula carried out a study which looked at 3 groups of volunteers (around 8 people in each group) divided into low, moderate and high caffeine users. The volunteers visited the lab 8 times at different times of day and night (7am, 1pm, 7pm and 1am). Before the tests began they swallowed either a caffeine capsule or a placebo capsule. In the lab they were given a series of performance tests covering short term memory, mental arithmetic, verbal reasoning (which is like logic), and a serial search task (which is a measure of vigilance).

Caffeine actually improved performance in more simple mental tasks like searching for one particular letter in a string of printed letters. Mental speed is the critical thing in this test.

Caffeine improved performance best at the 7am testing time - when the body's 24 hour rhythm of arousal is at its lowest.

By contrast Mitchell found that the high-caffeine user group didn't perform as well as the others on more complex tasks such as verbal reasoning.



10. Caffeine And Personality Differences

Recent research in Melbourne suggests that caffeine consumption may be tied in with personality differences including mood, or whether a person is a night owl or a lark (early morning person).

As the result of a questionnaire Dr Paula Mitchell found that so-called "night owls" or extreme evening people had much higher levels of caffeine usage than "larks" or extreme morning people. (Extreme evening people and extreme morning people each account for about 10% of the population). The evening people also scored higher on both the extroversion scale and the impulsivity, risk-taking scale. They typically find it difficult to get up in the morning and give themselves big hits of caffeine to wake themselves up. (It's quite possible they are actually suffering from caffeine withdrawal. In other words if they hadn't been drinking coffee the night before they may not have felt like this in the morning.)

Dr Mitchell also says there may be a link between extrovert behaviour and higher caffeine usage.

Caffeine seems to disrupt the body clock rhythms of extreme morning people. By contast the rhythms of the evening types are disturbed by the absence of caffeine. Dr Mitchell believes evening people use caffeine to keep their rhythms regular.

One of the strongest findings was that if morning people had caffeine after about 10am, their mood went down quite dramatically. This could be because caffeine has disrupted their underlying rhythms.



Producer : Richard Campbell

Writer : Geoffrey Burchfield

Editor : Meredith Hopes

Researcher : Joy Mitchell



Source from : http://www.abc.net.au/quantum/poison/caffeine/caffeine.htm