A patient is prescribed warfarin (Coumadin). What dietary teaching is most important?

Warfarin and vitamin k: Warfarin works by blocking Vitamin K-dependent clotting factors (II, VII, IX, X).

Diet teaching: DO NOT abruptly increase vitamin K-rich foods (leafy greens — kale, spinach, collards, broccoli): this will decrease INR (more clotting, less anticoagulation — risk of clot); DO NOT abruptly eliminate vitamin K foods: this will increase INR (less clotting, more anticoagulation — bleeding risk); CONSISTENT intake is the goal — if you eat spinach twice a week, keep eating it twice a week. This is a key teaching distinction: patients often think they must eliminate all vitamin K, but the instruction is CONSISTENCY, not elimination. Other warfarin interactions: alcohol increases INR; cranberry juice increases INR; many medications interact. Monitor INR regularly; report unusual bruising or bleeding.