Observations on Possible Effects of Daily Vitamin K Replacement,Especially Upon Warfarin Therapy

Abstract

Daily parenteral vitamin K supplement is now recommended by the US Food and Drug Administration (FDA) for patients receiving IV hyperalimentation. This is considered as preferable to the previous recommendations of weekly parenteral or oral supplement, or as in some cases no supplement at all. Supplemental vitamin K₁ will ensure adequate supplies for hepatic saturation and thus the production of clotting factors II, VII, IX, and X, plus the anticoagulants protein C, protein S, and protein Z. But this is not the entire story. This recommended supplement will affect other physiologic systems that also use vitamin K-dependent γ-carboxylation.

Vitamin K is not 1 molecule but rather 2 natural substances, vitamin K₁ and K_2, and the synthetic K₃'s. It is not understood, what, if any, effect may occur because of the saturation or competition from the vitamin K₁ upon the functioning of vitamins K₂ and the derivatives of K₃ in vivo upon bone mineralization, cell growth, and blood vessel health, all known to be influenced by the vitamins K. There are probably other physiologic systems yet to be studied relative to vitamins K and γ-carboxylation.

This review also considers the available research upon warfarin when given to patients receiving hyperalimentation and what effects the vitamin K supplements may have. Because studies to date have not controlled for vitamin K intake, consideration is given to whether one should expect any change in previously reported outcomes when using low-dose warfarin for prophylaxis against central vein thrombosis. Also considered are possible positive or negative effects that chronic warfarin therapy may have upon the other vitamin K-dependent systems under discussion.

This review offers a platform for further discussion and derived clinical research provoked by this new FDA recommendation.

Vitamin K and warfarin are involved in coagulation but also much more. They influence cell growth and apoptosis through cell signaling, bone mineralization, and blood integrity. Use of vitamin K supplements has a wider physiologic impact than just the coagulation system.