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Vitamin K is a family of structurally similar, fat-soluble vitamers found in foods and marketed as dietary supplements. [1] The human body requires vitamin K for post-synthesis modification of certain proteins that are required for blood coagulation ("K" from Danish koagulation, for "coagulation") or for controlling binding of calcium in bones and other tissues. [2]
Newborn infants are a special case. Plasma vitamin K is low at birth, even if the mother is supplemented during pregnancy, because the vitamin is not transported across the placenta. Vitamin K deficiency bleeding (VKDB) due to physiologically low vitamin K plasma concentrations is a serious risk for premature and term newborn and young infants.
Vitamin K 1-deficiency may occur by disturbed intestinal uptake (such as would occur in a bile duct obstruction), by therapeutic or accidental intake of a vitamin K 1-antagonist such as warfarin, or, very rarely, by nutritional vitamin K 1 deficiency. As a result, Gla-residues are inadequately formed and the Gla-proteins are insufficiently active.
This combination can lead to vitamin K deficiency and later onset bleeding. Vitamin K deficiency leads to the risk of blood coagulation problems due to impaired production of clotting factors II, VII, IX, X, protein C and protein S by the liver. More rarely VKDB can be caused by maternal medicines causing vitamin K deficiency in the newborn. [2]
Vitamin A deficiency affects one third of children under age 5 around the world, [33] leading to 670,000 deaths and 250,000–500,000 cases of blindness. [34] Vitamin A supplementation has been shown to reduce all-cause mortality by 12 to 24%.
Phytomenadione, also known as vitamin K 1 or phylloquinone, is a vitamin found in food and used as a dietary supplement. [6] [7] It is on the World Health Organization's List of Essential Medicines. [8] It is used to treat certain bleeding disorders, [7] including warfarin overdose, vitamin K deficiency, and obstructive jaundice. [7]
The liver utilizes vitamin K to produce coagulation factors that help the body form blood clots which prevent excessive bleeding. [2] [3] Vitamin K injections are administered to newborns as a preventative measure to reduce the risk of hemorrhagic disease of the newborn (HDN). [4] [5]
K 2 is both a tissue and bacterial product (derived from vitamin K 1 in both cases) and is usually found in animal products or fermented foods. [1] The number n of isoprenyl units in their side chain differs and ranges from 4 to 13, hence vitamin K 2 consists of various forms. [2] It is indicated as a suffix (-n), e. g. MK-7 or MK-9.