Addiction to caffeine is no storm in a teacup. Ben West looks at the dangers.

PEOPLE may at present be arguing passionately about the merits and dangers of cannabis, but an Army court martial last year vividly illustrated the possible hazards of using a far more popular drug. The court-martial was told that an Army officer's judgment was affected when he became addicted to large quantities of tea, which caused him allegedly to mishandle funds.

Major David Senior, 45, drank about 25 cups of tea a day, causing caffeinism, an addiction to tea or coffee, which is similar to alcoholism in that sufferers are the last to realise they have a problem.

That the humble cuppa could cause such problems will come as a surprise to many people. For although we worry about alcohol consumption and smoking, we seldom give a thought to the problems drinking coffee and tea can cause, problems that are increasingly likely as we follow American and European tastes, invariably choosing a strong caffeine-rich coffee in preference to a weaker cup of char.

Caffeine is the most widely consumed behaviour-modifying drug in the world. Although moderate doses can reduce drowsiness and fatigue and improve intellectual performance, too much of the substance can cause problems. It can put heavy demands on your kidneys and can cause - depending upon the amount consumed and tolerance to caffeine the individual has - confusion, irritability, nausea, restlessness, nervousness, insomnia, sweating, migraine attacks, tremor, tinnitus, palpitations and panic attacks. Some symptoms can be indistinguishable from anxiety neurosis.

Caffeine has a stimulant effect on all tissues and organs. Small amounts can improve the performance of skeletal muscles and the digestive system by increasing production of stomach acid, but too much can cause twitching of skeletal muscles and abdominal pains. Excess caffeine can also aggravate PMT and may even damage the nervous system itself. There's even a case of a soldier in the Indian army who was believed to have been blinded by drinking too much tea.

Because tea and coffee are powerful diuretics, excessive amounts can also increase a woman's risk of osteoporosis (brittle bone disease) in later life as calcium is lost in the urine.

Regular drinkers often find their tolerance to caffeine increases, and withdrawal symptoms from the substance can include headaches, irritability, tiredness, nausea, nervousness, muscle pains, and sweating.

In recent years coffee has been linked, sometimes tenuously, to a range of conditions including high cholesterol and strokes, miscarriage, schizophrenia and infertility, as well as cancer of the bladder, kidney, bowel, ovary, pancreas, and bones.

Many studies have conflicted with each other. A study by the University of Bristol found that people who drank the equivalent of four cups of coffee a day performed more efficiently throughout the day than those who drank less. A Danish study found that drinking more than nine cups of coffee a day reduces the risk of heart attacks. A study of 90,000 nurses found that those drinking two or three cups of coffee a day were more positive about life than non-coffee drinkers.

Tea has had a relatively good press. It's been credited with health benefits recently including reducing the risk of heart disease and strokes, lowering cholesterol levels, and suppressing some cancer-causing agents, but not because of the caffeine contained.

Thankfully, most experts agree that moderate caffeine consumption is unlikely to be harmful. But how do you define this? Gerard Derby in his book, Coffee and Health, defines high levels of caffeine intake as 10 cups of tea or coffee a day. The British Nutrition Foundation reckons that sticking to three or four cups of coffee a day, or its equivalent, shouldn't damage your health.

Consumption of between 300-400mg is unlikely to be harmful, but reduce your intake if you have raised blood pressure, kidney disease, or a history of heart disease. Pregnant and breastfeeding women should restrict their intake to 60mg, or a cup of coffee a day.

CAFFEINE COUNTS

n Average caffeine levels

(mg per 150ml cup)

Cocoa/drinking chocolate 10

Cola 20

Weak tea 40

Strong tea 60

Instant coffee 65

Weak ground coffee 80

Strong ground coffee 180

4oz bar of milk chocolate 25

4oz bar of dark chocolate 70

Painkillers (two tablets) 60