Which statement best explains how foods rich in Vitamin K affect warfarin therapy?

• A. Foods rich in Vitamin K can affect warfarin's anticoagulant effect.
• B. Vitamin K has no effect on warfarin therapy.
• C. Vitamin K-containing foods should be completely avoided.
• D. Only synthetic Vitamin K matters for warfarin interaction.

Answer: (A)

Vitamin K is needed to activate several clotting factors. Warfarin blocks the recycling of vitamin K, which lowers those active factors and increases bleeding risk. When you eat foods rich in vitamin K, more vitamin K is available, which can reduce warfarin’s effect and lower the anticoagulated state. If vitamin K intake changes abruptly, warfarin’s effect can shift, risking either clotting (with higher intake) or bleeding (with lower intake). So, the goal is a consistent vitamin K intake and close monitoring, not eliminating vitamin K or assuming it doesn’t matter.