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Vitamin K

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What other names is Vitamin K known by?

4-Amino-2-Methyl-1-Naphthol, Fat-Soluble Vitamin, Menadiol Acetate, Menadiol Sodium Phosphate, Menadione, Ménadione, Menadione Sodium Bisulfite, Menaquinone, Ménaquinone, Menatetrenone, Menatétrenone, Phytonadione, Methylphytyl Naphthoquinone, Phylloquinone, Phytomenadione, Vitamina K, Vitamine K, Vitamine Liposoluble, Vitamine Soluble dans les Graisses.

What is Vitamin K?

Vitamin K is a vitamin found in leafy green vegetables, broccoli, and Brussels sprouts. The name vitamin K comes from the German word "Koagulationsvitamin."

Several forms of vitamin K are used around the world as medicine. Vitamin K1 (phytonadione) and vitamin K2 (menaquinone) are available in North America. Vitamin K1 is generally the preferred form of vitamin K because it is less toxic, works faster, is stronger, and works better for certain conditions.

In the body, vitamin K plays a major role in blood clotting. So it is used to reverse the effects of "blood thinning" medications when too much is given; to prevent clotting problems in newborns who don't have enough vitamin K; and to treat bleeding caused by medications including salicylates, sulfonamides, quinine, quinidine, or antibiotics. Vitamin K is also given to treat and prevent vitamin K deficiency, a condition in which the body doesn't have enough vitamin K. It is also used to prevent and treat weak bones (osteoporosis) and relieve itching that often accompanies a liver disease called biliary cirrhosis. Vitamin K2 (menaquinone) is taken by mouth to treat osteoporosis and bone loss caused by steroids, as well as to lower total cholesterol in people on dialysis.

People apply vitamin K to the skin to remove spider veins, bruises, scars, stretch marks, and burns. It is also used topically to treat rosacea, a skin condition that causes redness and pimples on the face. After surgery, vitamin K is used to speed up skin healing and reduce bruising and swelling.

Healthcare providers also give vitamin K by injection to treat clotting problems.

An increased understanding of the role of vitamin K in the body beyond blood clotting led some researchers to suggest that the recommended amounts for dietary intake of vitamin K be increased. In 2001, the National Institute of Medicine Food and Nutrition Board increased their recommended amounts of vitamin K slightly, but refused to make larger increases. They explained there wasn't enough scientific evidence to make larger increases in the recommended amount of vitamin K.

Effective for...

  • Preventing bleeding problems in newborns with low levels of vitamin K (hemorrhagic disease). Giving vitamin K1 by mouth or as an injection into the muscles can prevent bleeding problems in newborns.
  • Treating and preventing bleeding problems in people with low levels of the blood clotting protein prothrombin. Taking vitamin K1 by mouth or as an injection into the vein can prevent and treat bleeding problems in people with low levels of prothrombin due to using certain medications.
  • An inherited bleeding disorder called vitamin K-dependent clotting factors deficiency (VKCFD). Taking vitamin K by mouth or injecting it intravenously (by IV) helps prevent bleeding in individuals with VKCFD.
  • Reversing the effects of too much warfarin used to prevent blood clotting. Taking vitamin K1 by mouth or as in injection into the vein can counteract too much anticoagulation caused by warfarin. However, injecting vitamin K1 under the skin does not seem to be effective. Taking vitamin K along with warfarin also seems to help stabilize blood clotting time in people taking warfarin, especially those who have low vitamin K levels.

Possibly Ineffective for...

  • Bleeding within the fluid-filled areas (ventricles) of the brain (intraventricular hemorrhage). Giving vitamin K to women at risk for very preterm births might reduce the severity of intraventricular hemorrhage in preterm infants. However, it does not seem to prevent intraventricular hemorrhage nor the brain injuries associated with intraventricular hemorrhage.

Insufficient Evidence to Rate Effectiveness for...

  • Breast cancer. Population research suggests that higher dietary intake of vitamin K2 is linked with a lower risk of developing breast cancer.
  • Cancer. Population research suggests that higher dietary intake of vitamin K2 is linked with a lower risk of cancer-related death. However, it does not seem to be linked with a lower risk of developing cancer. Higher dietary intake of vitamin K1 does not seem to be linked with a lower risk of cancer or cancer-related death.
  • Heart disease. Research suggests that higher dietary intake of vitamin K2 is associated with a lower risk of coronary calcification, which occurs when the inner lining of the coronary arteries develops a layer of plaque, as well as a lower risk of death caused by coronary heart disease. Dietary vitamin K2 can be obtained from cheese, other milk products, and meat. Dietary intake of vitamin K1 does not seem to have an effect on heart disease risk. However supplementation with vitamin K1 seems to prevent or reduce the advancement of coronary calcification.
  • Cystic fibrosis. People with cystic fibrosis can have low levels of vitamin K due to problems digesting fat. Taking a combination of vitamins A, D, E, and K seems to improve vitamin K levels in people with cystic fibrosis who have trouble digesting fat. Also, early research suggests that taking vitamin K by mouth for can enhance the production of osteocalcin, which plays a role in the body's bone-building and metabolic regulation. However, there is no reliable evidence suggesting it improves overall health in people with cystic fibrosis.
  • Diabetes. Early research suggests that taking a multivitamin fortified with vitamin K1 does not lower the risk of developing diabetes compared to taking a regular multivitamin.
  • High cholesterol. There is early evidence that vitamin K2 might lower cholesterol in people on dialysis with high cholesterol levels.
  • Liver cancer. Taking vitamin K2 does not seem to prevent liver cancer from recurring after curative or possibly curative treatment. However, some early research suggests that vitamin K2 might prevent the development of liver cancer in people with liver cirrhosis.
  • Lung cancer. Early research suggests that higher dietary intake of vitamin K2 is linked with a reduced risk of lung cancer and lung cancer-related death. Dietary intake of vitamin K1 does not seem to be linked with a reduced risk of these events.
  • Weak bones (osteoporosis). So far, research results on the effects of vitamin K on bone strength and fracture risk in people with osteoporosis don't agree.
  • Prostate cancer. Early research suggests that higher dietary intake of vitamin K2, but not vitamin K1, is linked with a reduced risk of prostate cancer.
  • Stroke. Population research suggests that dietary intake of vitamin K1 is not linked with a reduced risk of stroke.
  • Spider veins.
  • Bruises.
  • Scars.
  • Stretch marks.
  • Burns.
  • Swelling.
  • Other conditions.
More evidence is needed to rate vitamin K for these uses.

Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, and Insufficient Evidence to Rate (detailed description of each of the ratings).

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