Within this single arm pilot study patients with cystic fibrosis and liver steatosis receive choline chloride (2x0.5 gram three times a day) as a food supply for 88 days. D9-choline metabolism is measured before and after the intervention phase. Hypothesis of the study is, that supplying choline augments the secretion of phosphatidyl choline and lipoprotein (VLDL) from the liver and therefore results in a measurable reduction of the triglyceride storage of the liver.