 Fat malabsorption is common in individuals with cystic fibrosis CF and pancreatic insufficiency PI. This places them at risk for caloric, essential fatty acid, and choline deficiency, which may in turn, lead to growth failure and a poorer clinical course. The purpose of this research study is to find whether or not taking LYM-X-SORBTM over an 18-month period, every day, will correct the problem people with CF and PI have with absorbing fat and choline. Participation will help CF doctors and other healthcare professionals learn more about the potential benefits of LYM-X-SORBTM to children and adolescents with CF and PI. These benefits may include better absorption of fat, better choline status, better growth in height, weight, muscle and bone, better lungs, and improvement of health status. 