Taken together, the results of the present study suggest that even in settings of “normal” caloric intake a short-term change of dietary composition towards a more “unhealthy” dietary pattern e.g., a fat-, sugar- and cholesterol-rich diet can lead to a loss of tight junction proteins associated with increased lipidperoxidation and MMP-13 levels in the small intestine, as well as elevated portal bacterial endotoxin levels and an activation of dependent signaling cascades in the liver and the development of hepatic steatosis. This evidence concerns the gene MMP13 and fatty liver disease.