Vitamin K includes two natural vitamers: vitamin K1 and vitamin K2. Vitamin K2, in turn, consists of a number of related chemical subtypes, with differing lengths of carbon side chains made of isoprenoid groups of atoms.
Vitamin K1, also known as phylloquinone, phytomenadione, or phytonadione, is synthesized by plants, and is found in highest amounts in green leafy vegetables because it is directly involved in photosynthesis. It may be thought of as the “plant” form of vitamin K. It is active as a vitamin in animals and performs the classic functions of vitamin K, including its activity in the production of blood-clotting proteins. Animals may also convert it to vitamin K2.
Vitamin K2, the main storage form in animals, has several subtypes, which differ in isoprenoid chain length. These vitamin K2 homologues are called menaquinones, and are characterized by the number of isoprenoid residues in their side chains.
Physiological Function of Vitamin K
Vitamin K is a fat soluble vitamin that primarily acts as a cofactor in blood coagulation and bone matrix proteins. It is made up of a quinone and a phytyl group. The biochemical action dependent on vitamin K involves unique gamma-carboxylation of glutamyl residues of specific proteins. The result of the carboxylation is increased binding of calcium that is known to be required in blood clot formation and bone remodeling. There are two natural Forms of vitamin K which differ based on their phytyl group, phylloquinone, synthesized from plants and menaquinone, synthesized from bacteria.
Causes of Vitamin K Deficiency
Vitamin K deficiency primarily occurs in elderly primarily due to inadequate dietary intake and absorptive difficulties, frequently complicated by drug therapies.
Health concerns due to Vitamin K deficiency
Vitamin K deficiency results in an increase in the time required for blood to clot. The usual clinical manifestation is a tendency to hemorrhage. The measurement of prothrombin Lime in plasma reveals the vitamin K-dependent activation of prothrombin and other clotting factors. Prothrombin times longer than 12 seconds can indicate vitamin K deficiency. Vitamin K status is especially important in the elderly because of inadequate dietary intake and absorptive difficulties, frequently complicated by drug therapies. Monitoring vitamin K can help reduce osteoporotic bone fractures by identifying individuals whose bone loss is due to vitamin K deficiency. Calcium loss in such cases can be reduced by up to 50% with vitamin K supplementation.
Assessment of Vitamin K Status
Plasma Phylloquinone < 1 nmol/L
Plasma Uncler-carboxylated osteocakin > 20% Total Osteocalcin
Prothrombin time >12 seconds
Supplementation of Vitamin K
Adult Repletion: 500 to 1,000 micro-gramg/day
Buy Best or most Bio-Available or Active form of Vitamin K
Active form: Protein-bound vitamin K
Dietary sources of Vitamin K
Dietary sources of Vitamin K1 are:
- Green leafy vegetables
- Vegetable oils
- Dairy foods
Dietary sources of Vitamin K2 are
- Dairy Foods