Vitamin K is one of the fat soluble vitamins required for the formation of several of the proteins, called 'clotting factors', that regulate blood clotting. Vitamin K is actually 3 different compounds, all of which are fat soluble. It is absorbed from the upper small intestine with the help of bile (or bile salts) and pancreatic secretions, and then carried to the liver.

Vitamin K is also required for the formation of certain proteins which are important for the maintenance of healthy bones and teeth and in biosynthesis by gut bacteria/flora. New-born infants are routinely given vitamin K injections or supplements.

Vitamin K is also necessary for the synthesis of a protein that may help you regulate blood calcium levels. Calcium is usually associated with keeping your bones strong, and is also necessary for blood clotting. Serious problems with blood clotting may arise if you don't take enough of vitamin K as our blood takes a long time to clot. This can lead to excessive blood loss and increased risk of death from serious injuries.

Anticoagulant medications such as warfarin interfere with normal use of vitamin K in the body and changes in the quantities of vitamin K can change how these drugs work. People who are at risk of having problems related to abnormal blood clotting, such as those with a history of stroke or heart disease are often put on anti-coagulation therapy.

These medications reduce blood clotting by competing (interfering) with Vitamin K. Vitamin K is used to reduce the risk of bleeding in liver disease, jaundice, mal absorption, or in association with long-term use of aspirin or antibiotics. If you are a woman, it is important to note that vitamin K has been used in the treatment of heavy menstrual bleeding, and with vitamin C to treat morning sickness.

Vitamin K is needed for bones to use calcium. Vitamin K supplements may improve bone mass in postmenopausal women. Vitamin K deficiency is linked to osteoporosis because low levels have been found in those with the condition. Supplements of vitamin K have been used to treat this condition.

High intakes of vitamin K are linked to a lower risk of hip fracture in women. On the other hand, you can have lowered bone mineral density if you have been taking low amounts of vitamin K and be prone to developing bone fractures and osteoporosis.

Individuals with osteoporosis tend to have much lower blood levels of vitamin K than other people. Vitamin K plays a role in the formation of new bone. Vitamin K may prevent kidney stones. A vitamin K analog, K compound 5, may stop liver cancer growth. Some forms (water-soluble chlorophyll) help control body, fecal, and urinary odor. Water-soluble forms are used to treat skin wounds.

Research evidence suggests that vitamin K3, the synthetic form of vitamin K, may inhibit the growth of some bone marrow cells, specifically, chronic myelogenous leukemia (CML) cells, and enhance the chemotherapeutic effects of doxorubicin. Vitamin K also plays a key role in the synthesis of at least two proteins involved in calcium and bone metabolism. One of these proteins has been shown to be a strong inhibitor of vascular calcification, thus vitamin K appears to have a role in maintaining vascular health.

Vitamin K may influence bone metabolism through its effect on urinary calcium excretion or by inhibiting the production of bone reabsorbing agents.

Vitamin K is produced by bacteria, including the flora found in our gut. However, a newborn's gastrointestinal tract is typically sterile for a few days after birth. The production of Vitamin K and, therefore, clotting factors, begins by the fourth day of life, giving babies their ability to clot blood. This is why newborns are typically given Vitamin K injections shortly after birth.

Deficiency of vitamin K is more common in people with intestinal mal-absorption disorders or after bowel surgery.

It is important to remember that vitamin K can interfere with the action of anticoagulants such as warfarin. X-rays and radiation can raise vitamin K requirements. Vitamin K is excreted in breast milk, and crosses the placenta. Pregnant women and women who are breast-feeding should consult their health care provider before starting vitamin K supplements.

Your body may need more vitamin K if you are taking aspirin, cholestyramine, phenytoin, or mineral oil laxatives. Some snake venoms destroy vitamin K, which helps blood clot properly. Vitamin K may be injected to stop the bleeding from snakebite. If you are on antibiotics for a long time, you may end up with vitamin K deficiency. These drugs kill not only harmful bacteria, but also beneficial, vitamin K-activating bacteria in the gut.

A good multivitamin is the foundation of health and nutrition. Take a look at our scientific reviews of many of the popular brands for factors such as ingredients, areas of improvement, quality level, and overall value. If you are looking for a high quality liquid multivitamin, we suggest that you take a look at the Multivitamin Product Comparisons.

References
Bendich A, Decklebaum R. Preventive Nutrition: The Comprehensive Guide for Health Professionals. Totowa, NJ: Humana Press; 1997.

Booth SL, Centurelli MA. Vitamin K: a practical guide to the dietary management of patients on warfarin. Nutr Rev. 1999; Crowther MA, Donovan D, Harrison L, McGinnis J, Ginsberg J. Low-dose oral vitamin K reliably reverses over-anticoagulation due to warfarin. Thromb Haemost. 1998;79: 1116-1118.

Feskanich D, Weber P, Willett WC, Rockett H, Booth SL, Colditz GA. Vitamin K intake and hip fractures in women: a prospective study. Am J Clin Nutr. 1999;69:74-79.