The body prevents loss of blood through the process of blood clotting. Vitamin K, one of the fat-soluble vitamins, is necessary for proper formation of blood clots. In 1935, the Danish scientist Henrik Dam isolated vitamin K and published his findings regarding its requirement for blood clotting, naming it for the Danish and German words for clotting: "koagulation-vitamin." The body gets its vitamin K from ingestion of green leafy foods and the normal flora of bacteria in the large intestine that manufacture it as a byproduct.
Blood Clotting
The process of blood clotting is referred to as coagulation, which results in the formation of a blood clot, or thrombus, that prevents blood loss from damaged tissues. The platelets that are found circulating in the bloodstream bind together to form a plug that is then overlaid with a mesh of protein called fibrin via the process known as the clotting cascade. This structure is then further remodeled to form the final clot. Vitamin K is a vital requirement in the synthesis of four of the 13 proteins needed to maintain the clotting cascade. Vitamin K is so crucial to this process that those who take anticoagulant medications must also take pains to keep up their intake of vitamin K.
Vitamin K Requirements
Vitamin K is required at every stage of life, beginning at birth; newborns are given an injection of vitamin K to prevent a deficiency that causes hemorrhagic disease responsible for many newborn deaths worldwide. Vitamin K is not transmitted well though the placenta, and breast milk concentrations are low, so infants can be born with an existing vitamin K deficiency. The U.S. recommended daily intake for vitamin K are as follows: infants require 2.0 to 2.5 micrograms; children, 30 to 60 micrograms; adolescents, 75 micrograms; adult males, 120 micrograms; and adult females, 90 micrograms per day.
Dietary Sources
The body receives much of its vitamin K through daily nutrition sources. Vitamin K is found in abundance in the dark green leafy vegetables including kale, spinach, turnip greens, broccoli, Swiss chard, parsley, watercress, Brussels sprouts and cabbage. The chlorophyll that gives these plants their deep green color contains vitamin K. It can also be obtained by eating beef liver, asparagus, green tea, canola oil and soybean oil. Freezing can destroy some of the vitamin K in foods, but heating does not affect it.
Vitamin K Deficiency
Although a vitamin K deficiency is often a problem in newborns, it is rare for an adult to have one. The primary causes of a vitamin K deficiency are fat malabsorption problems, biliary obstruction, cystic fibrosis, diet deficiencies and anticoagulant medications. Symptoms include easy bruising, bleeding gums, heavy menstrual periods and poor blood clotting. Treatment consists of administration of vitamin K supplements, either orally or via injection.
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