Vitamin K1, also known as phylloquinone, is a fat-soluble vitamin that is essential for the synthesis of proteins involved in blood clotting and bone metabolism. It is found primarily in green leafy vegetables such as spinach, kale, collard greens, and broccoli, as well as in some vegetable oils like soybean and canola oil. Vitamin K1 is typically obtained through dietary sources, but it can also be synthesized by bacteria in the intestines. Vitamin K1 plays a critical role in the clotting process by activating clotting factors in the liver, which are necessary for the formation of blood clots to stop bleeding. It also helps regulate calcium metabolism by activating proteins that are involved in bone formation. A deficiency in vitamin K1 can lead to increased bleeding and bruising, as well as an increased risk of osteoporosis. However, deficiency is rare because the body can store vitamin K1 in the liver and recycle it to meet the body's needs.