Functions of Vitamin K
Vitamin K is necessary for the formation of prothrombin, a chemical required in blood clotting. Vitamin K helps in activation of seven blood clotting factor proteins that participate in series of reactions to form a clot and eventually stops the flow of blood. Vitamin K also participates in the activation of blood proteins, which greatly enhance their calcium binding properties. It is involved in bone formation by transporting calcium. It is also involved in a body process, phosphorylation, in which phosphate, when combined with glucose, passes through the cell membranes and is converted into glycogen.
Sources of Vitamin K
Green leafy vegetables, cheeses are good sources of Vitamin K. Besides dietary sources, Menaquinones are also synthesized by bacteria in colan and absorbed, contributing to about 10% of vitamin K. Synthetic vitamin K can be toxic. Supplemental vitamin K can interfere with the actions of some blood thinners.
Deficiency disorders of Vitamin K
Primary deficiency of Vitamin K is rare, but secondary deficiency may result from fat malabsorption syndrome. Prolonged use of antibiotics can destroy Vitamin K synthesizing bacteria in intestine leading to deficiency risk. New born infants feeding on breast milk may run the risk of Vitamin K deficiency.
Low levels of Vitamin K have been associated with low bone mineral density. Thus adequate intake of Vitamin K may help protect against hip fracture.
Disorder due to excess intake of Vitamin K
High doses of Vitamin K can reduce the effectiveness of anticoagulant drug. Vitamin A and E interferes with absorption of Vitamin K. Toxicity of Vitamin K in food is rare, as body excretes Vitamin K more rapidly than other fat soluble vitamins.