What the f*** does it do?

Vitamin K is used in the body to control blood clotting and is essential for synthesizing the liver protein that controls the clotting, called prothrombin. Vitamin K is known as the clotting vitamin, because without it blood would not clot. Some studies indicate that it helps in maintaining strong bones in the elderly. Elderly like Johnna.

Vitamin K activates at least three proteins involved in bone health, prothrombin being one of them. Prothrombin, the precursor to thrombin, is involved in bone formation and repair. The vitamin also adds chemical entities called carboxyl groups to osteocalcin and other proteins that build and maintain bone. Because of this, Vitamin K may decrease the incidence or severity of osteoporosis and slow bone loss.

In the intestines it assists in converting glucose to glycogen, which can then be stored in the liver and later used for energy.