Cystic Fibrosis (CF) is a complex disease with a wide range of clinical problems. Despite enzyme replacement therapy, children with cystic fibrosis (CF) may still have problems absorbing some nutrients. Detailed studies of the nutrient status of children with CF and have found low amounts of choline, an essential dietary nutrient, and altered levels of some amino acids in almost all patients. Choline is an essential dietary nutrient that is important in many important body functions, which include proving a source of methyl groups, the structure of cell membranes and in acetylcholine. Most choline is present in our diets in a fat known as phosphatidylcholine. Research studies have shown that children with cystic fibrosis do not absorb fat, including phosphatidylcholine very well. In previous studies, we showed that choline provided as a dietary supplement for 2 weeks improved choline status in children with cystic fibrosis.