Vitamin K: A Practical Guide to the Dietary Management of Patients on Warfarin

Warfarin has been successfully used in the medical management of thromboembolic disease for nearly six decades. It is widely assumed that a dietary vitamin K–warfarin interaction exists. To avoid this potential interaction, patients typically receive instructions to consume a constant dietary intake of vitamin K, and sufficient data exist to suggest that a constant dietary intake of vitamin K that meets current dietary recommendations of 65 to 80 mg/day is the most acceptable practice for patients on warfarin therapy. Data concerning the vitamin K content of commonly consumed foods, however, are not readily accessible to clinicians and patients. An understanding of the dietary vitamin K‐warfarin interaction, and dietary sources and usual intakes of vitamin K may facilitate successful anticoagulation for patients being treated with warfarin. ▪ Key Words: vitamin K, warfarin, anticoagulant phylliquinone