Vitamin K

Vitamin K is actually a group of compounds and the name vitamin K comes from the German word 'Koagulationsvitamin.'

Updated: June 16, 2022

Vitamin K is actually a group of compounds and the name vitamin K comes from the German word 'Koagulationsvitamin.' The most important of these compounds appears to be vitamin K1 and vitamin K2. Vitamin K1 is obtained from leafy greens and some other vegetables like broccoli, and Brussels sprouts. Vitamin K2 is a group of compounds largely obtained from meats, cheeses, and eggs, and synthesized by bacteria. 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.
Vitamin K plays a key role in helping the blood clot, preventing excessive bleeding. Unlike many other vitamins, vitamin K is not typically used as a dietary supplement.
Vitamin K2 is used to treat osteoporosis and steroid-induced bone loss in some cases.
Low levels of vitamin K can raise the risk of uncontrolled bleeding. While vitamin K deficiencies are rare in adults, they are very common in newborn infants. A single injection of vitamin K for newborns is standard. Vitamin K is also used to counteract an overdose of the blood thinner Coumadin.

Causes Of Vitamin K Deficiency:

You may be at higher risk if you:

  • Have a disease that affects absorption in the digestive tract, such as Crohn's disease or active celiac disease
  • Take drugs that interfere with vitamin K absorption
  • Are severely malnourished
  • Drink alcohol heavily

Uses of Vitamin K:

Vitamin K is used to :

  • reverse the effects of 'blood thinning' medications when too much is given
  • prevent clotting problems in newborns who don't have enough vitamin K
  • treat bleeding caused by medications including salicylates, sulfonamides, quinine, quinidine, or antibiotics.
  • treat and prevent vitamin K deficiency, a condition in which the body doesn't have enough vitamin K.
  • prevent and treat weak bones (osteoporosis)
  • 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.
  • vitamin K can be applied to the skin to remove spider veins, bruises, scars, stretch marks, and burns.
  • It can also be used topically to treat rosacea, a skin condition that causes redness and pimples on the face.
  • vitamin K is used to speed up skin healing and reduce bruising and swelling after surgery.

Vitamin is 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 for:

The Use of Vitamin K has Insufficient Evidence for the following Disease:

Athletic performance:

Taking vitamin K2 by mouth might improve exercise performance by increasing the work of the heart.

Blood disorder (beta-thalassemia):

Taking vitamin K2 by mouth along with calcium and vitamin D can improve bone mass in children with this blood disorder.

Breast cancer:

Higher dietary intake of vitamin K2 is linked with a lower risk of developing breast cancer.


Higher food intake of vitamin K2, but not vitamin K1, can have a reduced risk of death from cancer. But other research has linked a higher food intake of vitamin K1, but not vitamin K2, with a reduced risk of death from cancer.


Higher food intake of vitamin K2 is linked with a lower risk of getting cataracts.

Colorectal cancer:

Higher dietary intake of vitamin K is not linked with a reduced risk of cancer of the colon and rectum.

Heart disease:

Higher dietary intake of vitamin K2 has been linked with a reduced risk of heart disease, risk factors for heart disease, and death due to heart disease in older men and women. But vitamin K2 intake from food does not seem to be linked with a reduced risk a heart disease in people at high risk for this condition. Dietary intake of vitamin K1 has not been linked with a reduced risk of heart disease. But increasing vitamin K1 intake from food has been linked with a reduced risk of death due to heart disease. Also, taking vitamin K1 as a supplement seems to prevent or reduce the advancement of coronary calcification. This is a risk factor for heart disease.

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.
Taking vitamin K by mouth can enhance the production of osteocalcin. Osteocalcin plays a role in bone-building and metabolic regulation of the body. But there is no reliable evidence suggesting that vitamin K improves overall health in people with cystic fibrosis.


There is no evidence that taking a multivitamin fortified with vitamin K1 does not lower the risk of developing diabetes compared to taking a regular multivitamin.

Skin rash associated with a type of cancer medicine:

People who are given a certain type of anticancer medicine often develop skin rash. Applying a cream containing vitamin K1 helps prevent skin rash in people being given this type of medicine.

High cholesterol:

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 recurrence. But some early research shows that taking vitamin K2 reduces the risk of liver cancer in people with liver cirrhosis.

Lung cancer:

Higher intake of vitamin K2 from food 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.

Multiple sclerosis (MS):

Interferon is a medicine that helps people with MS. This medicine often causes a rash and burning of the skin. Applying vitamin K cream modestly reduces rash and burning in people with treated with interferon.

Prostate cancer:

Higher dietary intake of vitamin K2, but not vitamin K1, is linked with a reduced risk of prostate cancer.

Rheumatoid arthritis:

Taking vitamin K2 along with arthritis medicine reduces markers of joint swelling better than taking arthritis medicine alone.


Dietary intake of vitamin K1 is not linked with a reduced risk of stroke.

Other conditions:

Applying Vitamin K may reduce bruises, burns, scars, spider veins, stretch marks, swelling.

Side Effects & Safety:

The two forms of vitamin K (vitamin K1 and vitamin K2) are safe for most people when taken by mouth or injected into the vein in recommended dose. Most people do not experience any side effects when take it in the recommended amount daily.
Precautions & Warnings for the following Conditions:

Pregnancy and breast-feeding:

Vitamin K is considered safe for pregnant and breast-feeding women when taken in the recommended amount on daily basis. However, don't use higher amounts without the advice of your healthcare professional.


The form of vitamin K known as vitamin K1 is safe for children when taken by mouth or injected into the body in right quantity.


Vitamin K1 might lower blood sugar levels. Regularly monitor your blood sugar levels if you have diabetes and take vitamin K1.

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.

Reduced bile secretion:

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


Many drugs can interfere with the effects of vitamin K. They include antacids, blood thinners, antibiotics, aspirin, and drugs for cancer, seizures, high cholesterol, and other conditions. Do not take the combination of Warfarin (Coumadin) and Vitamin K as this will have a major interaction.
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.


Most people get enough vitamin K from their diets. However, the recommended adequate intake of vitamin K, both from food and other sources is given below:

By Mouth:

  • 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.

There isn't enough scientific information to determine recommended dietary allowances (RDAs) for vitamin K. So daily adequate intake (AI) recommendations have been formed instead in terms of micrograms. 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.

Natural Food Sources of Vitamin K:

Good natural food sources of vitamin K include:  

  • Vegetables like spinach, asparagus, and broccoli 
  • Legumes like green beans 

You can also meet your daily requirement with foods that have lesser amounts of vitamin K. These include eggs, strawberries, meat like liver etc.
Vitamin K supplements can only be used on advise of your health care provider. People using Coumadin for heart problems, clotting disorders, or other conditions may need to watch their diets closely to control the amount of vitamin K they take in. They should not use vitamin K supplements unless advised to do so by their health care provider.

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