Creatine supplementation can help protect against fatty liver caused by a high-fat diet, but can make fatty liver caused by alcohol worse. The researchers studied mice and found that creatine reduced fat buildup and liver damage in mice on a high-fat diet. However, when combined with alcohol, creatine increased liver fat and damage by affecting how the body processes alcohol. This shows that creatine has different effects on fatty liver diseases depending on the cause, with protective effects against non-alcoholic fatty liver disease but harmful effects on alcoholic fatty liver disease.