Last week, a study found that excessive coffee consumption (four or more cups per day) could raise mortality risks for younger people. This week, another study is continuing the tradition of conflicting data about the healthfulness of coffee.

The study, to be published in the journal Hepatology, shows that coffee and tea could counter act non-alcoholic fatty liver disease (NAFLD). The study’s authors found that caffeine stimulates liver cells to metabolize stored lipids. Mice that were fed a high-fat diet to induce fatty livers saw their liver fat reduced when given caffeine. The study suggests that four cups of coffee or tea per day could prevent NAFLD from developing further.

“This is the first detailed study of the mechanism for caffeine action on lipids in liver and the results are very interesting,” said Dr. Paul Yen, one of the study’s authors and a professor at the Duke University School of Medicine. “Coffee and tea are so commonly consumed and the notion that they may be therapeutic, especially since they have a reputation for being “bad” for health, is especially enlightening.”

NAFLD is strongly associated with both diabetes and obesity. 30% of U.S. adults are estimated to have NAFLD, and 70% of people who are obese and have diabetes have the condition. According to the study, there is currently no known treatment for NAFLD, save for diet and exercise.