· 22-year study of 125,000 people 'solidifies' linkage · Caffeine is not the key, as drinking tea has no effect

Drinking as little as one cup of coffee a day could help protect you from liver disease caused by alcohol, according to research published today.

People who drink one cup of coffee are 20% less likely to have alcoholic cirrhosis than those who abstain from doing so.

And the protective effect increases with the more coffee you drink: People who drink two or three cups a day are 40% less likely to contract cirrhosis, while those who drink four or more cups are 80% less likely to suffer the disease.

The findings, conducted by researchers at the Kasier Permanente, in Oakland, California, are thought to be the largest study to look at the inverse relationship between coffee and cirrhosis. The link was first reported by researchers at the same institute in 1993 but this new study - of 125,000 people over 22 years - "solidifies the association", Arthur L Klatsky, the lead author of the study, said.

Dr Klatsky, who was involved in the earlier research, added: "Consuming coffee seems to have some protective benefits against alcoholic cirrhosis, and the more coffee a person consumes the less risk they seem to have of being hospitalised or dying of alcoholic cirrhosis. We did not see a similar protective association between coffee and non-alcoholic cirrhosis."

The researchers, whose findings are published in the US journal Archives of Internal Medicine, followed more than 125,000 health plan members who underwent a medical examination between 1978-1985 and who, at the time, had no diagnosed liver disease. Participants filled out a questionnaire detailing how much alcohol, coffee and tea they drank daily.

By the end of 2001, 330 participants had been diagnosed with liver disease, including 199 with alcoholic cirrhosis - caused by the consumption, each day, of three or more units of alcohol.

Researchers - who only counted those who had been hospitalised or died because of the disease - found that the more coffee a person drank the less likely they were to develop alcoholic cirrhosis.

Drinking tea had no effect, suggesting the ingredient that protects against cirrhosis is not caffeine.

Blood tests conducted on the 5% of drinkers who consumed the most alcohol confirmed that coffee drinkers were less likely to have high levels of enzymes in the liver - a key indicator of liver damage.

Dr Klatsky added: "Even allowing for statistical variation, this shows there is a clear association between coffee consumption and protection against alcoholic cirrhosis.

"This is not a recommendation to drink coffee. Nor is it a recommendation that the way to deal with heavy alcohol consumption is to drink more coffee. And while there is very little evidence that moderate coffee drinking - say up to four cups a day - is harmful to the health, that's not the message we want to get across. There is a lot of harm caused by heavy drinking other than liver damage."

Dr Klatsky said that if caffeine were the key protective ingredient, he would expect to have seen some protection for heavy tea drinkers.

"We can't answer why this has happened," he said. "The value of this study is that it may offer us some clues as to the biochemical processes taking place inside liver cells that could help in finding new ways to protect the liver against injury."

Cirrhosis, caused by thickening of the normal tissue, causes progressive damage and impaired function of the liver. There are numerous causes including viruses, obesity or genetic problems - but excess alcohol is the main culprit.

Figures published in The Lancet this year show that Britons are drinking themselves into the grave at a sharply increasing rate. In the 1950s England and Wales had low rates of liver cirrhosis deaths - for men 3.4 per 100,000 a year and for women 2.2. By 2001 rates were 14.1 for men and 7.7 for women.

While the US remains the world's biggest consumer of coffee - with the average American drinking 3.2 cups a day - British men now drink an average of 1.7 cups, and women 1.5 cups a day.