In warfarin therapy, which dietary consideration is important to monitor to maintain therapeutic anticoagulation?

• A. Sodium intake
• B. Sugar intake
• C. Protein intake
• D. Vitamin K intake

Answer: (D)

Vitamin K intake is the key dietary factor to monitor in warfarin therapy. Warfarin works by blocking the recycling of vitamin K, which lowers the production of vitamin K–dependent clotting factors. If someone eats a lot more vitamin K–rich foods than usual, it can counteract warfarin and move the INR toward normal or lower, reducing anticoagulation. If intake drops suddenly, warfarin’s effect can become too strong, raising the INR and bleeding risk. Because of this, maintaining a consistent daily amount of vitamin K and avoiding large, sudden changes in intake is essential for keeping anticoagulation in the therapeutic range. Clinicians may adjust the dose if dietary patterns change. Foods high in vitamin K include leafy greens like spinach, kale, and lettuce. Other dietary factors listed do not directly affect warfarin in the same way.