From the Guidelines
Vitamin K2 is not the same as vitamin K1 in terms of its interaction with warfarin, as it can bypass the warfarin-sensitive vitamin K epoxide reductase step in the formation of vitamin KH2. The difference in interaction between vitamin K1 and K2 with warfarin is crucial for patients on warfarin therapy, as vitamin K1 is primarily involved in blood coagulation and its intake needs to be consistent to avoid affecting INR levels and anticoagulation stability 1. Vitamin K2, on the other hand, is more involved in bone health, cardiovascular function, and calcium regulation, and its supplementation may be less likely to interfere with warfarin's anticoagulant effects. Key points to consider include:
- Vitamin K1 is reduced to vitamin KH2 by a warfarin-resistant vitamin K reductase, while vitamin K2 can overcome the effect of warfarin by bypassing the warfarin-sensitive vitamin K epoxide reductase step 1.
- Warfarin primarily inhibits the recycling of vitamin K1, which is essential for blood clotting factors, but has less impact on vitamin K2's functions.
- Patients on warfarin therapy should maintain consistent vitamin K1 intake rather than avoiding it completely, as sudden changes can affect INR levels and anticoagulation stability.
- Vitamin K2 supplementation may be considered for patients on warfarin therapy, but only under the guidance of a healthcare provider, as it may still have some effects on anticoagulation.
From the Research
Vitamin K1 and K2: Effects on Warfarin
- Vitamin K1 is the form of vitamin K that is commonly recommended for reversing warfarin-related coagulopathy 2.
- However, vitamin K2 is also used in some countries, such as Japan, for the same purpose 2.
- Studies have shown that vitamin K2 can counteract the effects of warfarin on blood coagulation 3.
- The interaction between warfarin and vitamin K2 has been investigated in a rat aorta loop model, which suggests that high doses of vitamin K2 can reduce the effect of warfarin on thrombosis 3.
Comparison of Vitamin K1 and K2
- Vitamin K1 and K2 have different effects on warfarin anticoagulation, with vitamin K1 being more commonly used to reverse warfarin-related coagulopathy 2, 4.
- Vitamin K1-containing multivitamin supplements can disrupt warfarin anticoagulation in vitamin K1-depleted patients 4.
- The effects of vitamin K2 on warfarin anticoagulation are less well understood, but studies suggest that it can also counteract the effects of warfarin 3.
Clinical Implications
- The use of vitamin K1 or K2 to reduce warfarin's activity is a clinical option, with oral vitamin K1 being a safer and more cost-effective alternative to parenteral administration 5.
- The administration of vitamin K1 or K2 can help to attenuate the elevation of international normalized ratio (INR) and potentially reduce the risk of bleeding in patients taking warfarin 6, 5.