Vitamin K belongs to the class of fat-soluble vitamins, and is notable for its role in the blood clotting process. The vitamin also plays a part in bone formation and in cellular growth. Whether it comes from food sources or in supplement form, vitamin K is necessary for optimal health.
Clotting
Blood clots, or coagulates, through a series of interdependent events. Specifically, there are seven clotting proteins in the coagulation process that depend on vitamin K to bind calcium ions and be activated. These vitamin K-dependent coagulation factors are synthesized in the liver, and as a result liver disease can lead to a deficiency in vitamin K-dependent clotting factors and an increased risk of hemorrhaging.
Bone Mineralization
Researchers have isolated three proteins in bone that are dependent on vitamin K. Osteocalcin, or bone Gla protein, is produced by the bone-forming osteoblast cells, and helps bind minerals in the process of bone formation. Matrix Gla protein (MGP) is found in soft tissue, cartilage and bone, and appears to prevent the calcification of soft tissue and cartilage while aiding bone growth and development. Protein S is also synthesized by the osteoblasts, but how it affects bone health is yet unclear. Children with a deficiency in protein S will, however, experience increased blood clotting and lower bone density.
Cellular Growth
Vitamin K is also important for the functioning of the protein Gas6, which is found in the nervous system, heart, lungs, stomach and kidneys. Gas6 seems to regulate cellular growth and is involved in cell signaling. Gas6's regulation of cell growth results in cellular adhesion, proliferation and protection against cell death. The protein also helps maintains homeostasis in blood vessels.
Sources
Vitamin K is plentiful in green vegetables including cabbage, broccoli, kale and spinach, as well as beef liver. The vitamin is also available in supplement form, but most people get adequate amounts of it from their normal diet.
Recommended Intake
Although vitamin K deficiencies are rare, the Institute of Medicine recommends a daily intake of 120 mcg for adult males and 90 mcg for adult females, with younger people requiring less of the vitamin.
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