Vitamin K
About Vitamin K
Vitamin K is a family of fat soluble compounds comprising K1, phylloquinone, found mainly in leafy green vegetables, K2, the menaquinones produced by bacteria and found in fermented foods such as natto as well as in cheese and egg yolks, and K3, menadione, a synthetic form. Its name comes from the German word Koagulation, reflecting its discovery by Henrik Dam in the 1930s as a factor needed for blood clotting. Vitamin K is required for gamma carboxylation of clotting factors II, VII, IX and X and of the anticoagulant proteins C and S. Newborns have low stores, and a prophylactic vitamin K injection at birth is routinely given in many countries to prevent vitamin K deficiency bleeding. Warfarin works by antagonizing vitamin K recycling, so consistent dietary vitamin K is relevant for people taking it. Vitamin K also activates osteocalcin in bone and matrix Gla protein in blood vessels, and low intake has been associated with poorer bone health. Possible cardiovascular effects of K2 remain under study.
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