Coffee and tea might reduce liver disease risks
the risk of chronic liver disease by half, reports new research
"The principle finding of this large, national, population-based prospective study was that higher coffee and tea consumption reduced the risk of chronic liver disease," said the researchers from the National Institute of Diabetes and Digestive and Kidney Disease.
Drinking coffee has already been associated with a lower risk of liver cancer and a reduced risk of death from liver cirrhosis.
The new, long-term study followed 9,849 participants in the National Health and Nutrition Examination Survey (NHANES I), conducted between 1971 and 1975, and also analysed follow-up studies, conducted between 1982 and 1993.
"Persons who drank more than two cups of coffee or tea per day had less than half the risk [of chronic liver disease] of those consuming less than one cup per day," wrote Dr Constance Ruhl and Dr James Everhart in the article to be published in Gastroenterology.
However they added: "Despite this… protective effect of coffee on the liver, a mechanism is not yet known, nor have there been clinical trials. Furthermore, it is uncertain what component or combination of components might be protective."
The researchers noted that various coffee constituents, including caffeine, cafestol, kahweol (nontriglyceride lipid components of coffee oils), and antioxidants from coffee bean extracts, have been found to have a favourable effect on the liver in experimental studies.
Chronic liver disease (CLD) affects 5 million people in the US. The two most common causes of CLD are hepatitis C infection and non-alcoholic fatty liver disease. However, both of these causes, "were not recognized through most of the years of the study," admitted the researchers.
"This is a problem inherent to population-based studies that span decades. Nevertheless, it would be clinically relevant to know if protective effects found in the current study apply to all chronic liver diseases or just to one or two major causes," they wrote.
Worldwide daily caffeine consumption averages one and a half cups, while the US average is more than three and a half cups.