high-dose vitamin K1 and vitamin K2 from MK4 & MK7 Vitamin K has two major functions in the human body: it contributes to normal blood clotting and to maintaining normal bones. Vitamin K also has its name because it helps the blood to clot. K stands for coagulation, the medical term for the clotting of blood or lymph. The group of K vitamins belongs to the fat-soluble vitamins, which means that vitamin K is better absorbed and stored in the body together with oils or (fatty) food.