December 02, 2005 - A study published today in the American Gastroenterological Association (AGA) journal Gastroenterology found that people at high risk for liver injury may be able to reduce their risk for developing chronic liver disease significantly by drinking more than two cups of coffee or tea daily. This preventative effect was only seen in people at higher risk for liver disease due to heavy alcohol intake, being overweight or having diabetes or iron overload. This is the first study to take a prospective look at the relationship between coffee and tea consumption and chronic liver disease in the general U.S. population.
"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 Constance E. Ruhl, MD, PhD, who conducted the study with colleague, James E. Everhart, MD, MPH. "In addition, we hope the findings will offer guidance to researchers who are studying liver disease progression."
Chronic liver disease is an ongoing injury to the cells of the liver, resulting in inflammation that lasts longer than six months. Its causes are numerous, including viruses, obesity, alcohol, metabolic or immunologic abnormalities, and side effects from various medications. Chronic liver diseases include cirrhosis, fibrosis and hepatitis. According to the most recent estimates from the National Center for Health Statistics, nearly 28,000 people die of chronic liver disease each year and there are more than 5 million prevalent cases of chronic liver disease and cirrhosis in the United States.
Researchers at the National Institute of Diabetes and Digestive and Kidney Diseases and Social & Scientific Systems, Inc. conducted an analysis of patients using the first National Health and Nutrition Examination Survey (NHANES I) and the NHANES I Epidemiologic Follow-Up Study. The study population included 9,849 participants whose coffee and tea intake was evaluated and who were followed for a median of 19 years. In this analysis, coffee and tea intake was measured in cups, ranging from 0 to 16 cups per day with a median of two cups per day. Findings showed that those who consumed 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.
Over the last few years, there has been a growing body of evidence that coffee decreases the risk of elevated liver enzymes, cirrhosis and liver cancer. This study provides support for a protective effect of coffee on chronic liver disease and cirrhosis, and extends these findings to the general U.S. population. However, the study does not provide evidence that coffee and tea protect against chronic liver disease from individual causes, such as fatty liver disease or viral hepatitis.
"In the analysis, we determined that caffeine was partly responsible for the protective effect found. We believe that investigations into the mechanism of action of caffeine for protecting the liver and its clinical application are needed," said Dr. Ruhl.