Vitamin K is a fat-soluble vitamin.
Primarily, vitamin K is important for bone formation and blood clotting. It also helps in calcium transport around the body. Those taking anticoagulant drugs such as warfarin or heparin should avoid vitamin K except under medical supervision.
Vitamin K is found in leafy green vegetables like collards, kale, spinach, Swiss chard and broccoli.
National Institutes of Health, Office of Dietary Supplements