Vitamin K – All Facts That You Need to Know

vitamin k

Vitamin K – All Facts That You Need to Know

What is it?

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

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 К 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 К is used to speed up skin healing and reduce bruising and swelling.

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

An increased understanding of the role of vitamin К in the body beyond blood clotting led some researchers to suggest that the recommended amounts for dietary intake of vitamin К be increased. In 2001, the National Institute of Medicine Food and Nutrition Board increased their recommended amounts of vitamin К 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 К.

How effective is it?

Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate.

The effectiveness ratings for VITAMIN К are as follows:

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 К-dependent clotting factors deficiency (VKCFD). Taking vitamin К 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 К along with warfarin also seems to help stabilize blood clotting time in people taking warfarin, especially those who have low vitamin К levels.

Possibly ineffective for…

  • Bleeding within the fluid-filled areas (ventricles) of the brain (intraventricular hemorrhage). Giving vitamin К 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 К due to problems digesting fat. Taking a combination of vitamins A, D, E, and K seems to improve vitamin К levels in people with cystic fibrosis who have trouble digesting fat. Also, early research suggests that taking vitamin К 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 К 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 К for these uses.

How does it work?

Vitamin К is an essential vitamin that is needed by the body for blood clotting and other important processes.

Are there safety concerns?

The two forms of vitamin К (vitamin K1 and vitamin K2) are LIKELY SAFE for most people when taken by mouth or injected into the vein appropriately. 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 К is considered safe for pregnant and breast-feeding women. Don’t use higher amounts without the advice of your healthcare professional.

Children: The form of vitamin К known as vitamin K1 is LIKELY SAFE for children when taken by mouth or injected into the body appropriately.

Diabetes: The form of vitamin К known as vitamin K1 might lower blood sugar levels. If you have diabetes and take vitamin K1, monitor your blood sugar levels closely.

Kidney disease: Too much vitamin К can be harmful if you are receiving dialysis treatments due to kidney disease.

Liver disease: Vitamin К is not effective for treating clotting problems caused by severe liver disease. In fact, high doses of vitamin К can make clotting problems worse in these people.

Reduced bile secretion: People with decreased bile secretion who are taking vitamin К might need to take supplemental bile salts along with vitamin К to ensure vitamin К absorption.

Are there interactions with medications?

Do not take this combination.

Warfarin (Coumadin)
Vitamin К is used by the body to help blood clot. Warfarin (Coumadin) is used to slow blood clotting. By helping the blood clot, vitamin К 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.


Be cautious with this combination.

Medications for diabetes (Antidiabetes drugs)

Vitamin K1 might decrease blood sugar. Diabetes medications are also used to lower blood sugar. Taking vitamin K1 along with diabetes medications might cause your blood sugar to go too low. Monitor your blood sugar closely. The dose of your diabetes medication might need to be changed.

Some medications used for diabetes include glimepiride (Amaryl), glyburide (DiaBeta, Glynase PresTab, Micronase), insulin, pioglitazone (Actos), rosiglitazone (Avandia), and others.

Are there interactions with herbs and supplements?

Coenzyme Q-10
Coenzyme Q-10 is chemically similar to vitamin К and, like vitamin К, can promote blood clotting. Using these two products together can promote blood clotting more than using just one. This combination can be a problem for people who are taking warfarin to slow blood clotting. Coenzyme Q-10 plus vitamin К might overwhelm the effects of warfarin and could allow the blood to clot.

Herbs and supplements that might lower blood sugar
Vitamin K1 might lower blood sugar. Using vitamin K1 along with other herbs and supplements that might lower blood sugar might lower blood sugar too much. Herbs that might lower blood sugar include devil’s claw, fenugreek, guar gum, Panax ginseng, and Siberian ginseng.

There is a concern that tiratricol might interfere with vitamin K’s role in blood clotting.

Vitamin A
In animals, high doses of vitamin A interfere with vitamin K’s ability to clot blood. But it’s not known if this also happens in people.

Vitamin E
High doses of vitamin E (e.g. greater than 800 units/day) can make vitamin К less effective in clotting blood. In people who are taking warfarin to keep their blood from clotting, or in people who have low vitamin К intakes, high doses of vitamin E can increase the risk of bleeding.

Are there interactions with foods?

Butter, Dietary Fat
Eating foods containing butter or other dietary fats in combination with vitamin К – containing foods, such as spinach, seems to increase vitamin К absorption.

What dose is used?

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 К is typically used; however, the exact dose needed is determined by a lab test called the INR.
There isn’t enough scientific information to determine recommended dietary allowances (RDAs) for vitamin К, so daily adequate intake (AI) recommendations have been formed instead: The AIs are: infants 0-6 months, 2 mcg; infants 6-12 months, 2.5 mcg; children 1-3 years, 30 mcg; children 4-8 years, 55 mcg; children 9-13 years, 60 mcg; adolescents 14-18 years (including those who are pregnant or breast-feeding), 75 mcg; men over 19 years, 120 mcg; women over 19 years (including those who are pregnant and breast-feeding), 90 mcg.

Other names
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.

Original article: MedlinePlus – Vitamin K

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