Vitamin K

Vitamin K: Overview

The vitamin K present in plant foods is called phylloquinone; while the form of the vitamin present in animal foods is called menaquinone.  Both of these vitamins are absorbed from the diet and converted to an active form called dihydrovitamin K.

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Vitamin K deficiency can be prevented by assuring that the diet contains foods such as green leafy vegetables (spinach, lettuce, broccoli), alfalfa, brussels sprouts and cabbage, which are good sources, containing about 8mg/kg.  Cow's milk is also a good source of the vitamin, as are soy foods, egg yolks, and cauliflower.  Soybean oil, canola oil and olive oil are good sources of the vitamin, while corn oil and peanut oil are very poor sources.

A portion of the body's vitamin K is supplied by bacteria living in the intestine rather than by dietary sources.

Function; Why it is Recommended

Vitamin K is a fat-soluble set of molecules that are required for the health of the human population.  First discovered in the treatment of chicks with hemorrhagic diseases, vitamin K is vitally involved in the process of blood clotting.  Three forms of biologically active vitamin K are known, they are menadione, phylloquinone, and menaquinone-7. Not only is vitamin K involved in the synthesis of clotting factors VII, IX, and X; it is also involved in the conversion of pre-prothrombin to prothrombin (the precursor to thrombin), which is important in fibrin blood clot formation.

The most common deficiency of vitamin K is at birth since vitamin K does not traverse well through the placenta, nor through breast milk.  It is very common to give an intramuscular vitamin K shot to newborns for this reason.

When needed for the correction of prolonged bleeding due to over-anticoagulation with warfarin, oral vitamin K (1-5mg) was found to be as effective as IV administration, but had a slower onset of action. [Br J Haematol 2001;115(1): pp.145-149]


The US RDA recommends 1mcg of vitamin K per kilogram of weight per day.  This means a person weighing 165 lbs (75 kilos) should ingest 75mcg of vitamin K daily.  The RDA for vitamin K is 80mcg for adult males, 65mcg for adult females, and 5mcg for newborn infants.

Counter-Indicators and Warnings

People on any drug that is intended to change the blood clotting time, like Coumadin, should contact their physician before taking large amounts of vitamin K.

Vitamin K can help with the following:


Bruising Susceptibility

Low levels of vitamin K are sometimes suspected as a contributing factor to bruising.  Vitamin K is found in foods such as green leafy vegetables, soyfoods, egg yolks and cauliflower.


IBS (Irritable Bowel Syndrome)

Those with IBS should ensure adequate vitamin K intake as a deficiency can worsen the symptoms of IBS, including bloody stool, indigestion and diarrhea.


Pregnancy-Related Issues

The U.S. RDA is 65mg.

Menorrhagia (Heavy Periods)

Based on its ability to help blood clot normally, vitamin K has been proposed as a treatment for excessive menstrual bleeding and is beneficial for some women.  Although bleeding time and prothrombin levels in women with menorrhagia are typically normal, the use of vitamin K (often in the form of chlorophyll) does have limited research support.  Green leafy vegetables and other sources of vitamin K should be eaten freely.


Vitamin K Requirement

Adults with vitamin K deficiency are treated with daily oral doses of 10mg phylloquinone for one week.  The prognosis for correcting vitamin K deficiency and associated blood-clotting problems, is excellent.

Organ Health


Low vitamin K levels may be supplemented with 100 to 500mcg per day.

Tumors, Malignant

Multiple Myeloma

Many patients on high dose chemotherapy for lymphoma or myeloma test positive for prothrombin precursor PIVKA II.  These are proteins induced by vitamin K absence or antagonism.

Non-Hodgkin's Lymphoma

Many patients on high dose chemotherapy for lymphoma or myeloma test positive for prothrombin precursor PIVKA II.  These are proteins induced by vitamin K absence or antagonism.

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Vitamin K can help prevent the following:


Osteoporosis - Osteopenia

Not enough vitamin K in the system is a predisposing risk factor for osteoporosis.  New research has shown that this little known vitamin is the key to calcium balance in the body.

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