Which vitamin interacts with aluminum-containing antacids and affects chemotherapy effectiveness?

• A. Vitamin C
• B. Vitamin K
• C. Vitamin E
• D. Grapefruit

Answer: (B)

The concept here is how aluminum-containing antacids can interfere with the absorption of certain vitamins, especially fat-soluble ones, when taken around the same time as the vitamins. Aluminum antacids can bind nutrients in the gut or disrupt micelle formation, reducing the absorption of fat-soluble vitamins A, D, E, and K. Vitamin K stands out in the chemotherapy context because it is essential for blood clotting; if its absorption is reduced, vitamin K deficiency can occur, increasing bleeding risk and potentially complicating chemotherapy schedules, dosing, and safety. That direct link to coagulation and treatment management makes it the most relevant choice. The other options are less connected to this specific interaction: Vitamin C is water-soluble, and while it has its own interactions, it is not the primary concern with aluminum-containing antacids in this scenario; Vitamin E is another fat-soluble vitamin but doesn’t have as direct a tie to chemotherapy management as vitamin K; grapefruit is not a vitamin and its relevance is more about drug metabolism than nutrient absorption.