Vitamin K is a fat-soluble vitamin used by the body to assist in the formation of clotting factors continually circulating in the blood. Produced in the liver with the assistance of vitamin K, these clotting factors provide the protection needed to prevent spontaneous bleeding within the body.
Sources of Vitamin K
Vitamin K can be found in two forms: exogenous and endogenous. Exogenous, or dietary sources of vitamin K, are found in animal meat such as turkey, chicken and beef; leafy green vegetables are another primary source. Supplements in the form of liquids, pills or capsules are another exogenous form of vitamin K available. Endogenous, or vitamin K produced within the body, is made by normal bacteria and stored in the liver.
Vitamin K Deficiency
Lack of vitamin K can result in spontaneous bleeding anywhere in the body. Vitamin K is used to make clotting factors that allow the body to control bleeding. Spontaneous bleeding in the gastrointestinal tract results in bloody stools and under the skin results in easy bruising, while bleeding in the brain results in stroke. Causes of vitamin K deficiency in adults include liver disease such as cirrhosis or poor dietary intake. In newborns, deficiency can be due to an immature liver and the inability of the placenta to transmit vitamin K, in addition to the low amount of vitamin K within breast milk.
Vitamin K Toxicity
Vitamin K has not been described and is not believed to cause toxicity. Due to its ability to affect blood clotting, large amounts of vitamin K have been associated with the interference of desired effects of certain medications, such as warfarin, or coumadin, used to thin out the blood for various conditions. Oral intake of vitamin K is considered safe.
Treatment
Vitamin k deficiency is treated by increasing the intake of foods that are rich in vitamin K or the addition of a vitamin supplement along with dietary changes. While toxicity is not commonly an issue, too much vitamin K interfering with blood thinning medications is managed by limiting certain foods or adjusting the medication. Before making any changes to your diet or medications, discuss with your health care provider.
References
- "Harrison's Principles of Internal Medicine "; Robert M. Russell, Paolo M. Suter; 2008
- USDA National Nutrient Database for Standard ReferenceS
- "Merck Manual of Diagnosis and Therapy"; Justin Kaplan M.D.; 2006
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