Cup that cheers and drives you mad

Britain's favourite beverage is in the dock. The hot brown liquid drunk by over 30 million adults every day was this week blamed for turning a sensible man dotty and leading him into moral turpitude.

Major David Senior, an army officer accused of fiddling the books on rations allowances, told a court martial on Tuesday that his 20-year love affair with tea had affected his judgement. He claimed to have drunk a gallon a day and said the caffeine in the brew had left him addicted.

Specialists yesterday concluded that Major Senior was consuming almost one gram of caffeine a day, three times more than the average tea or coffee drinker and sufficient to cause symptoms, including confusion, anxiety and trembling.

Tea contains 40-50mg of caffeine in an average cup compared with 65mg in a cup of instant coffee and over 100 mg in ground coffee. Professor Vincent Marks, dean of medicine at the University of Surrey, said excessive caffeine consumption could lead to aberrant behaviour.

"If I had been called as an expert witness in a similar case I would have advanced it as a plausible explanation. But talk of caffeine addiction is an abuse of the term. If you stop the caffeine, even at high levels, the worst you get is a headache."

Caffeine - "nature's stimulant" according to Professor Marks - is the world's most widely consumed mood-altering drug. In small quantities, it is almost certainly good for us, improving short-term memory, boosting muscle power and increasing alertness. Tea, whether green or black, Chinese or Indian, taken with milk or without, also has protective effects against heart disease and cancer.

A group of north American Indians living in Canada who chain-drink cups of tea were found to consume caffeine at the rate of one and a half grams a day without ill effects. Tolerance varies with anxious, nervy people most strongly affected and some, such as pregnant women, slower to metabolise it, so that with repeated doses, blood levels rise.

Doctors say that for most people up to 400mg a day of caffeine is unlikely to cause side-effects. But it is easy to exceed this level. Coffee contains more caffeine than tea and can be made stronger. The drug is also present in soft drinks and chocolate.

Three cups of ground coffee (115mg of caffeine each), a can of cola (40mg) and a 4oz bar of plain chocolate (80mg) would take a person over the 400mg limit.

A study in the New England Journal of Medicine showed even moderate caffeine users may suffer withdrawal symptoms. The only cure is ... another cuppa.