Its role in maintaining the clotting cascade is so important that people who take anticoagulants such as war far in (Coumadin) must be careful to keep their vitamin K intake stable. Recently, researchers have demonstrated that vitamin K is also involved in building bone. Low levels of circulating vitamin K have been linked with low bone density, and supplementation with vitamin K shows improvements in biochemical measures of bone health.
There are two naturally occurring forms of vitamin-K, vitamin K1 and vitamin K2. Vitamin K1 is synthesized by plants and is the predominant form in the diet. Therefore, people who do not regularly eat a lettuce salad or green, leafy vegetables are likely to be deficient in their intake of vitamin K. While, vitamin K2 comes from animal sources and synthesis by intestinal bacteria.
Roles of Vitamin K in the Biological System Coagulation (blood clotting) The ability to bind calciumions (Ca2+) is required for the activation of the seven vitamin K-dependent clotting factors, or proteins, in the coagulation cascade. The term, coagulation cascade, refers to a series of events, each dependent on the other, that stop bleeding through clot formation. Vitamin K-dependent coagulation factors are synthesized in the liver. Consequently, severe liver disease results in lower blood levels of vitamin K-dependent clotting factors and an increased risk of uncontrolled bleeding (hemorrhage).
Some oral anticoagulants, such as war far in (Coumadin), inhibit coagulation through antagonism of the action of vitamin K. Large quantities of dietary or supplemental vitamin K can overcome the anticoagulant effect of vitamin K antagonists, so patients taking these drugs are cautioned against consuming very large or highly variable quantities of vitamin K in their diets.