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.
How does it work?
Vitamin K is an essential vitamin that is needed by the body for blood clotting and other important processes.
- Treating and preventing vitamin K deficiency. Vitamin K1 can prevent and treat vitamin K deficiency.
- Preventing certain bleeding or blood clotting problems. Vitamin K1 can prevent bleeding or blood clotting problems in newborns.
- Reversing the effects of too much warfarin used to prevent blood clotting. Taking vitamin K1 can counteract too much anticoagulation caused by warfarin.
- 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.
- Cystic fibrosis. Early research suggests that taking vitamin K by mouth for one month 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.
- 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.
- High cholesterol. There is early evidence that vitamin K2 might lower cholesterol in people on dialysis with high cholesterol levels.
- Spider veins.
- Stretch marks.
- Other conditions.
Side Effects & Safety
Vitamin K is safe for most people. Most people do not experience any side effects when taking in the recommended amount each day.
Special Precautions & Warnings:Pregnancy and breast-feeding: When taken in the recommended amount each day, vitamin K is considered safe for pregnant and breast-feeding women, but don't use higher amounts without the advice of your healthcare professional.
Kidney disease: Too much vitamin K can be harmful if you are receiving dialysis treatments due to kidney disease.
Liver disease: Vitamin K is not effective for treating clotting problems caused by severe liver disease. In fact, high doses of vitamin K can make clotting problems worse in these people.
Major Interaction Do not take this combination
- Warfarin (Coumadin) interacts with VITAMIN K
Vitamin K is used by the body to help blood clot. Warfarin (Coumadin) is used to slow blood clotting. By helping the blood clot, vitamin K might decrease the effectiveness of warfarin (Coumadin). Be sure to have your blood checked regularly. The dose of your warfarin (Coumadin) might need to be changed.
The following doses have been studied in scientific research:
- For bleeding disorders such as hypoprothrombinemia: 2.5-25 mg of vitamin K1 (phytonadione).
- For counteracting bleeding that can occur when too much of the anticoagulant warfarin is given: 1-5 mg of vitamin K is typically used; however, the exact dose needed is determined by a lab test called the INR.