Vitamin K is used for which bodily process?

• A. Blood clotting
• B. Vision
• C. Calcium absorption
• D. Energy production

Answer: (A)

Vitamin K’s main job is to enable blood clotting by helping the liver synthesize and activate several clotting proteins. It serves as a cofactor for gamma-carboxylation of glutamate residues on factors II, VII, IX, and X, as well as proteins C and S. This modification creates binding sites for calcium, which is needed for the coagulation cascade to proceed and for a stable clot to form. Without enough vitamin K, these clotting factors can’t function properly, leading to a greater bleeding tendency. This is why vitamin K is given to newborns to prevent hemorrhagic disease. It isn’t involved in vision or calcium absorption or energy production, which rely on other nutrients and pathways.