Final answer:
The nurse should instruct the client to avoid Vitamin K-rich foods while taking warfarin to prevent blood clotting.
Step-by-step explanation:
The nurse should instruct the client to avoid foods with excessive amounts of Vitamin K while taking warfarin.
Vitamin K is necessary for proper formation of prothrombin, an enzyme that converts the protein fibrinogen into fibrin, which holds blood clots together. Warfarin works by inhibiting the action of vitamin K, which helps prevent blood clotting.
Therefore, if a client on warfarin consumes excessive amounts of vitamin K, it can counteract the anticoagulant effects of the drug and increase the risk of blood clots.