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Coffee ... friend or foe

Most of us have been caffeine abusers at some stage in our lives. I can remember writing my doctoral thesis and being kept awake and sustained by innumerable cups of coffee. I wrote my thesis in about ten days (and some unkind "friends" suggested that it showed!) but I certainly couldn't have done it without my coffee. Nowadays life is a little less frenetic but I still drink at least three cups of coffee a day and often four or five. I am incapable of starting the day until my heart and brain have been kick-started by my first dose of caffeine, usually in the form of tea. Thereafter I alternate between tea and coffee. While at work I would probably drink coffee from choice but it is free and therefore lousy, so tea provides a substitute.

Both tea and coffee contain caffeine; a large cup of ground coffee provides around 130 mg of the substance compared with around 90 mg for the instant variety and 75 mg for a large cup of tea. Cola drinks, such as Pepsi and Coca Cola contain around 30 mg (mind you it wasn't too long ago that Coca Cola actually did contain cocaine!). Caffeine is addictive at levels of around 600-700 mg a day, that's around 7 large cups of instant coffee. As with most other addictive drugs, a caffeine abuser undergoes withdrawal symptoms when deprived of the product. I'm relatively fortunate in that I seem to have reasonable tolerance to caffeine and have never experienced these symptoms. Withholding caffeine from an addict produces headaches, feelings of nausea and great lethargy (one caffeine withdrawal symptom I do suffer from).

The drug itself has a variety of effects. For most of us it increases alertness and provides a feeling of well-being. For older people, at least one cup a day increases the libido. In asthmatics, caffeine may act as a bronchodilator and open up air passages. Apart from withdrawal symptoms which are induced when deprived of the drug, caffeine does have another down side. It takes quite a long time to be cleared from the system, which means that the dose from one cup of coffee may not have been cleared from the blood stream by the time a second or even third cup has been imbibed. By the end of the day, an unwitting person may be carrying a high caffeine load. This causes difficulties in getting to sleep and ensures that what sleep there is, is of diminished quality. Caffeine may also cause heart arrhythmias.

The half-life of caffeine is between three and seven and a half hours depending upon the individual (the term half-life refers to the time needed to rid the system of half of the initial dose). Smoking decreases the half-life which may be why heavy smokers are often also heavy coffee drinkers .. perhaps they need more coffee to produce the desired effects?

Caffeine is one of the few drugs which is still legal in modern athletics. Athletes are allowed to take in an amount which does not produce more than 12 micrograms per milliliter of urine .. this equates to around nine large cups of instant coffee in the average person. Researchers point out that this leads to the ludicrous situation where levels which would impair athletic performance are banned, whereas levels which may enhance performance are allowed. Marathon runners take caffeine in tablet form or as rectal suppositories. I admit to having used the first method to improve my marathon running performances but have never considered the second (it sounds acutely uncomfortable). Caffeine is reputed to increase the amount of fat which is burned during endurance competitions, thereby saving the crucial glycogen stores and allowing them to last a little longer. Modern pentatheletes and shooters may take caffeine to improve their concentration. It is a dangerous practice, an overdose may actually impair motor co-ordination.

Many of us reach for the coffee jug when things become stressful, while the British are renowned for their love of caffeine during difficult times... "Never mind dear, I'll make us a nice cup of tea" has probably been said more often than any other phrase of similar length. At times of stress, this is the worst thing we could do. Caffeine heightens anxiety. The body produces several natural tranquilizers, one of which is adenosine. Caffeine interferes with the adenosine so that even small amounts of coffee or tea can raise anxiety levels.

Until recently, coffee was implicated in raising the risk of heart attack but a recent study has suggested that this is not the case. Nonetheless a Norwegian study has shown that blood cholesterol levels increase in proportion to the amount of coffee imbibed and cholesterol in itself may contribute to heart disease. Heavy coffee consumption (more than five cups a day) can increase lung cancer risks amongst smokers by up to 400%. Anyone that smokes is already playing Russian roulette, drinking lots of coffee as well is just asking for trouble.

As with most things, caffeine is fine in moderation. For me, one of life's many pleasures is sitting back in a comfortable chair with a good book, supping on a freshly brewed cup of filter coffee.

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