Production of prothrombin in the body depends primarily on which vitamin?

The production of prothrombin, which is a key protein in the blood clotting process, primarily depends on vitamin K. This vitamin is essential for the synthesis of several proteins that are required for blood coagulation, including prothrombin itself.

Vitamin K functions as a cofactor for the enzyme gamma-glutamyl carboxylase, which modifies certain glutamic acid residues on prothrombin to enable its functional activity. Without sufficient vitamin K, the body cannot produce adequate levels of prothrombin or other clotting factors, leading to increased bleeding risks.

Other vitamins, such as D, C, and A, have different roles in the body. Vitamin D is primarily involved in calcium metabolism and bone health, vitamin C is crucial for collagen synthesis and immune function, and vitamin A is important for vision and immune response. However, none of these vitamins play a direct role in the synthesis of prothrombin. Hence, vitamin K’s specific involvement in the blood coagulation process makes it the correct answer in this context.