So popular that it has inspired an idiom

Vocabulary: coffee 词汇: 咖啡

Do you drink a lot of coffee? The water boiling in the kettle, the aroma, the first mouthful from the cup in the morning – so many people see it as part of a ritual that it inspired an expression in English: 'Wake up and smell the coffee!'

I read the other day in the New Scientist magazine that coffee contains a stimulant, caffeine, which is the planet's most popular "psychoactive drug". In the United States alone, more than 90% of adults are estimated to use it every day. That's a lot of people!

Organisations which research public health thought it too. They're concerned about the addition of caffeine to products such as waffles, energy drinks and chewing gum. Lynne Goldman, dean of the George Washington University School of Public Health, says that many people don't know how much caffeine they are taking. As a result they could have insomnia, indigestion or high blood pressure.

I don't want to have any of that but I must say that when I can't have any coffee I feel a bit tired, have a mild headache and find it difficult to concentrate. Scientists say that these must be the withdrawal symptoms of caffeine - because coffee can cause an addiction.

But if you are a coffee lover like me, you shouldn't be afraid because in moderation, caffeine may have some positive effects. A study in the American Journal of Clinical Nutrition linked drinking coffee and tea with a lower risk of diabetes.

There is an interesting story behind the use of coffee. Stephen Braun, author of Buzz: The Science and Lore of Alcohol and Caffeine, says that the substance became popular in Europe with the industrial revolution. There was a race for productivity during that time.

And some famous people believed that coffee has creative powers. French novelist and playwright Honoré de Balzac and German composer Ludwig van Beethoven are said to have liked it a lot.

American film-maker David Lynch ate at the same Los Angeles diner every day for seven years. He drank up to seven cups of coffee with lots of sugar every time, which he said would guarantee him "lots of ideas".

What about you: Does coffee fill you with ideas? Is it an important part of your social life?