Which one of the following vitamins has a role in blood clotting ?

Vitamin K is essential for the process of blood coagulation (clotting). It serves as a critical cofactor for the enzyme gamma-glutamyl carboxylase, which facilitates the post-translational modification of specific glutamate residues into gamma-carboxyglutamate (Gla) residues in various proteins. This modification is vital for the biological function of several procoagulant factors, including Factor II (prothrombin), VII, IX, and X, as well as anticoagulant proteins like Protein C and S. Without sufficient vitamin K, these clotting factors cannot bind calcium or function correctly, leading to impaired coagulation and potential bleeding disorders [1]. While other fat-soluble vitamins like A, D, and E have roles in vision, bone mineralization, and antioxidant defense respectively, only Vitamin K is directly required for the synthesis of functional blood-clotting proteins [1].

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1. [1] https://medlineplus.gov/ency/article/002399.htm