Bioavailability of Vitamin E for cellular uses is a problem in CF patients. A pancreatic insufficiency and an adverse bile acid conjugation that results from an abnormal glycine/taurine ratio of bile acids likely cause this situation. Consequently, serum Vitamin E is notoriously low in CF. Taurine's third role in CF is in the promotion of vitamin E absorption, by reducing the glycine/taurine ration of bile acids in the duodenal juice of CF patients, thereby providing an intestinal environment conducive to the uptake of Vitamin E.