Which vitamin is used to treat bleeding disorders or overdose of oral anticoagulants?

Vitamin K is essential for the synthesis of certain clotting factors in the liver, specifically factors II, VII, IX, and X, which are critical for proper blood coagulation. When there is a bleeding disorder or an overdose of oral anticoagulants, which work by inhibiting the action of vitamin K, administering vitamin K can help restore the body's ability to clot properly. This is particularly important in reversing the effects of certain blood thinners, allowing for the correction of a coagulopathy (disruption in the normal clotting process) and preventing excessive bleeding.

In contrast, the other vitamins listed do not have this role; for instance, vitamin C is involved in collagen synthesis and iron absorption, vitamin D plays a crucial role in calcium metabolism and bone health, and vitamin B12 is significant for red blood cell formation and neurological function. Therefore, vitamin K stands out as the necessary vitamin for treating bleeding disorders related to clotting factor deficiencies or anticoagulant overdoses.