This is a clinical trial with a cross over design investigating the effect of the proton pump
inhibitor omeprazole on fat malabsorption in subjects with cystic fibrosis and pancreatic
insufficiency. Participants will be randomized to receive either omeprazole or placebo for 28
days, then cross over and receive omeprazole or placebo for another 28 days. Markers of fat
absorption will be measured after each treatment course.