With the exception of pancreatic insufficiency resulting in impaired digestion, other aspects of CF are less readily related to loss of CFTR function. Nutritional problems can persist even with adequate oral enzyme supplementation [9] and neutralization of gastric acid to improve lipase function [10], and may involve both impaired digestion and absorption of nutrients [11]. Inadequate absorption or assimilation of nutrients appears to be of greater importance because even with adequate oral enzyme supplementation nutrition is rarely fully corrected [11]. There is also excessive mucus accumulation in the CF intestine, and inappropriate inflammation is common [12]. Mucus is involved in obstruction of the gut which occurs frequently in CF infants (called meconium ileus, MI) and adults (called distal intestinal obstruction syndrome, DIOS) [11,13]. And, similar to CF airways, there is also an inflammation of the CF intestines [14,15]. These changes are less directly related to specific mutations in the CFTR gene and are likely related to other differences in individual genetic makeup.