A client who is taking an antibiotic develops diarrhea. As the client resumes a regular diet, the nurse offers yogurt and buttermilk, but also observes that the client has several small bruises. Which additional dietary change should the nurse offer?

Antibiotics can suppress the normal gut flora that synthesizes vitamin K, leading to reduced production of this fat-soluble vitamin. Vitamin K is essential for the synthesis of clotting factors II, VII, IX, and X; without adequate vitamin K, the coagulation cascade is impaired. The clinical sign here — small bruises appearing without significant trauma — strongly suggests impaired clotting, which points directly to vitamin K deficiency. Offering foods rich in vitamin K, such as dark leafy greens (spinach, kale), broccoli, and fermented dairy products, helps restore clotting factor synthesis. The yogurt and buttermilk already offered are appropriate for restoring gut flora and addressing diarrhea, but they do not specifically target the bruising. Increased proteins rich in iron addresses anemia (fatigue, pallor) rather than bruising or coagulation defects. Reduced cholesterol and fats is a cardiac-focused intervention with no relevance to antibiotic-induced bruising. Potassium-rich fruits address electrolyte imbalances commonly associated with diarrhea but do not correct the clotting problem. Recognizing that prolonged antibiotic use depletes gut bacteria responsible for vitamin K synthesis, and that vitamin K deficiency manifests as easy bruising and bleeding tendency, leads clearly to the recommendation of vitamin K-rich foods as the most appropriate additional dietary intervention for this client.