Coffee and tea may reduce the risk of serious liver damage in people who drink alcohol too much, are overweight, or have too much iron in the blood, researchers reported on Sunday.

The study of nearly 10,000 people showed that those who drank more than two cups of coffee or tea per day developed chronic liver disease at half the rate of those who drank less than one cup each day.

The study, conducted by the National Institute of Diabetes and Digestive and Kidney Diseases and Social & Scientific Systems, Inc., found that coffee provided no protection to people at risk of liver disease from other causes, such as viral infections.

"While it is too soon to encourage patients to increase their coffee and tea intake, the findings of our study potentially offer people at high-risk for developing chronic liver disease a practical way to decrease that risk," said Dr. Constance Ruhl, who helped lead the study.

"In addition, we hope the findings will offer guidance to researchers who are studying liver disease progression."

Writing in the American Gastroenterological Association journal Gastroenterology, Ruhl and colleagues said caffeine seemed to hold the key.

They analyzed the records of 9,849 participants in a government survey whose coffee and tea intake was evaluated and who were followed for about 19 years.