Acta Scientiarum Polonorum Technologia Alimentaria

Vitamin K belongs to the family of fat-soluble vitamins and plays an important role in hemostasis, bone metabolism and may affect cerebral sphingolipid synthesis. It is a cofactor necessary for posttranslational γ-carboxylation of glutamyl residues in selected proteins such as the osteocalcin, and procoagulation factors II, VII, IX, X. Vitamin K deficient individuals appear to have more undercarboxylated proteins, which are functionally defective. The vitamin K deficiency has been frequently documented in patients with cystic fibrosis. The main possible causes of this deficiency include: fat malabsorption due to pancreatic exocrine insufficiency, cholestatic or  noncholestatic liver disease, reduced production of vitamin K by colonic flora related to chronic antibiotic treatments, bowel resections and increased mucous accumulation in the bowel. CF patients are more prone to osteopenia, caused by chronic vitamin K shortage, than to coagulopathy. Despite available evidence, which strongly suggests that all CF patients are at risk for developing vitamin K deficiency, its supplementation doses have not been established. Recent recommendations from Europe and the UK have suggested varied doses ranging from 0.3 mg/day to 10 mg/week. Further studies, both cross sectional and longitudinal interventional, are still required to determine routine and therapeutic supplementation doses.