Vitamin K is needed in the body for proper clotting. Most people obtain enough of the vitamin through diet alone but there are supplements available. An excess of vitamin K in healthy adults will not cause a problem and is often used to combat side effects of liver problems, but contact your doctor before using it as a supplement, as vitamin K can negatively interact with certain medications or other supplements.
Vitamin K
Vitamin K is a fat-soluble vitamin and is important for blood clotting, or coagulation. There are two naturally occurring forms of vitamin K: phylloquinone and menaquinone. Phylloquinone occurs in plants and is consumed in the diet. Menaquinone is produced by bacteria in the intestines but only a small amount can be absorbed, according to the Merck Manuals. The only supplemental form of vitamin K in the U.S. is phytonadione, which is considered safer, less toxic and stronger --- and it works faster, according to the National Institutes of Health.
Function
Vitamin K's primary function is for blood clotting but it is also important for bone mineralization, according to the Linus Pauling Institute. Three proteins in bone are vitamin K dependent: osteocalcin, matrix Gla protein and protein S. Osteocalcin. Matrix Gla protein is found not only in bone but also in cartilage and soft tissue, including blood vessels. It is believed to prevent calcification of soft tissue and cartilage while maintaining normal bone growth and development. Another vitamin K dependent protein, Gas6, is found throughout the nervous system, heart, lungs, stomach, kidneys and cartilage. It appears to regulate cell growth.
Liver
The liver is the largest solid organ in the body, and is located right under the rib cage. It is also one of the most important, since it cleans your blood by removing toxins. The liver produces bile that aids in the digestion of food, as well as stores energy in the form of sugar called glycogen. All nutrients pass through the liver in the blood before going to the rest of the body. It helps to process the nutrients in ways the body can use it. Anything that should not be in the body is sent to the intestines to be excreted from the body.
Significance
Vitamin K dependent coagulation factors are synthesized in the liver, according to the Linus Pauling Institute. Liver problems inhibit the synthesis of vitamin K, decreasing the body's ability to form clots. Supplemental vitamin K is often used to reduce the risk of bleeding in liver diseases and increase the body's ability to form clots. There is no known toxicity for phylloquinone and menaquinone but the synthetic form of vitamin K called menadione can be toxic, according to the Linus Pauling Institute. Menadione given by injection induces liver toxicity; therefore it is no longer used. People with severe liver disease should not be given vitamin K, as high doses can make clotting problems worse, according to Medline Plus.
Considerations
Vitamin K is found in a variety of foods such as green leafy vegetables, soybeans and cow milk. The recommended daily allowance for vitamin K is 80 mg per day for adult males and 65 mg per day for adult females. Many diseases may impair the absorption of vitamin K and a supplement may be needed. Talk with your doctor first. Even though there is no known toxicity, vitamin K supplements should not be taken with certain medications or severe liver disease.
