|Also Known As:
|| menaphthone, menaquinone, phylloquinone, phytonadione,
Vitamin K is a fat-soluble vitamin, which means it is absorbed most
effectively when ingested with dietary fat. It is best known for its role in
helping blood clot properly after an injury. Vitamin K is helpful in this
situation because it is responsible for making clotting factors in the liver.
Vitamin K also plays an important role in bone health.
Vitamin K comes from the foods that we eat. Plus, bacteria that normally
reside in the intestines are able to make vitamin K. Antibiotics may interfere
with this normal production. Other circumstances that may lead to vitamin K
- Health problems that can prevent the absorption of vitamin K (such as
gallbladder or biliary disease which may alter the absorption of fat), cystic
fibrosis, celiac disease, and Crohn's disease
- Ingestion of excessive amounts of mineral oil
- Liver disease
- Use of blood-thinning medications (such as warfarin, see
- Ongoing or significant diarrhea (particularly in breast fed infants)
- Long-term use of total parenteral nutrition (TPN; nutrition provided
- Continuing hemodialysis
- Serious burns
It is also important to note, that breast fed infants may be at an increased
risk for vitamin K deficiency because human milk is not a very good source of
this nutrient. Interestingly, though, if a mother eats lots of green vegetables
on a daily basis, she can improve the amount of vitamin K in breast milk. In
addition, the elderly may also be at an increased risk for vitamin K deficiency
they tend take many medications, eat insufficient amounts of vegetables, and may
have bacterial overgrowth that impacts vitamin K production in the gut.
Vitamin K deficiency is rare because gut bacteria can produce enough of this
vitamin, even if dietary intake is low. Vitamin K deficiency can lead to
excessive bleeding (hemorrhage) which may begin as oozing from the gums or nose.
Echymoses (bleeding below the skin) and excessive bruising may also be symptoms
of vitamin K deficiency.
Vitamin K protects the body against the following:
Vitamin K is used to reduce the risk of
bleeding in liver disease, malabsorption syndromes as described earlier, or in
association with long-term use of antibiotics. Vitamin K has been used in the
treatment of heavy menstrual bleeding. Use of vitamin K for liver disease,
although often attempted, is not generally successful. This is particularly true
in the late stages of the disease, because at that point the liver is unable to
make the blood clotting factors, no matter how much vitamin K is present.
In the US, Canada, Great Britain, and many other countries, all newborns
receive vitamin K injections to prevent the possibility of hemorrhage
(particularly in the brain) just after delivery. Newborns are at risk for
bleeding in the brain because of the trauma of coming through the birth canal
during delivery. Vitamin K is not readily transferred from mother to child
during pregnancy. Therefore, even though vitamin K deficiency in the newborn is
very rare, it is considered sufficiently dangerous to warrant these measures.
Newborns at greatest risk for vitamin K deficiency are those who are born
prematurely or whose mother had to take seizure medications during the
pregnancy. Mothers on seizure medications are often given oral vitamin K for 2
weeks prior to delivery.
Vitamin K is needed for proper use of calcium in
bones. Higher vitamin K levels correspond to greater bone density, while low
levels of vitamin K have been found in those with osteoporosis. There is
increasing evidence that vitamin K supplements improve bone health and reduce
risk of bone fractures, particularly in postmenopausal women who are at risk for
osteoporosis. In addition, studies of other groups (such as male and female
athletes) have also shown bone enhancing benefits from vitamin K supplements.
Some snake venoms work by destroying vitamin K, and
thus the body's ability to clot blood clot. Vitamin K may be injected to stop
the bleeding from snakebite.
Because of involvement of the pancreas
(responsible for making enzymes that help fat absorption) and often the liver
with this condition, vitamin K deficiency is common in people with cystic
fibrosis. Therefore, supplementation is frequently recommended. Vitamin K
deficiency in those with cystic fibrosis is worsened by their recurrent need for
Vitamin K may help to prevent the formation of
kidney stones. (It is interesting to note that vegetarians, who tend to have a
high vitamin K intake, rarely have kidney stones.)
Chlorophyll (a water-soluble source of vitamin K in
plant foods) helps control body, fecal, and urinary odor.
Water-soluble forms may be used topically to treat
skin wounds. This may be due to the antioxidant effect of chlorophyll.
In addition, early test tube studies suggest that vitamin K3 (a synthetic
form of vitamin K) may inhibit the growth of certain cancerous bone marrow
cells, specifically, chronic myelogenous leukemia (CML) cells. CML is one type
of leukemia that is classified as a myeloproliferative disorder. Some
researchers are concerned, however, that this form of vitamin K may cause
serious anemia in people. More research is needed to assess if this synthetic
form of vitamin K is safe and useful for people with CML.
Foods that contain a significant amount of vitamin K include beef liver,
green tea, turnip greens, broccoli, kale, spinach, cabbage, asparagus, and dark
green lettuce. Chlorophyll, which is water soluble, is the substance in plants
that gives them their green color and provides vitamin K.
Freezing foods may destroy vitamin K, but heating does not affect it.
There are three forms of vitamin K:
- Vitamin K1 (phylloquinone, the natural version of K1 and phytonadione,
the synthetic type of K1)
- Vitamin K2 (menaquinone)
- Vitamin K3 (menaphthone or menadione)
K1 and K3 are both available as part of multivitamin complexes or alone, in 5
mg tablets. These fat-soluble forms are an excellent source of vitamin K.
Water-soluble chlorophyll is the most common form of vitamin K found over the
counter. It is available in tablet, capsule, and liquid forms. Only the topical
form is used to treat skin wounds and body odor.
|How to Take It|
As with all supplements, check with a healthcare provider before taking
vitamin K or giving it to a child. In general, people with vitamin K
deficiencies related to malabsorption (such as gallbladder or biliary disease,
cystic fibrosis, celiac disease, and Crohn's disease) will benefit most from a
multivitamin containing vitamin K, rather than an individual vitamin K
supplement. In certain circumstances, vitamin K may be administered by injection
in to a vein or muscle by a healthcare professional.
Daily intake for dietary vitamin K (according to the U.S. RDA) are listed
- Infants birth to 6 months: 2 mcg
- Infants 7 to 12 months: 2.5 mcg
- Children 1 to 3 years: 30 mcg
- Children 4 to 8 years: 55 mcg
- Children 9 to 13 years: 60 mcg
- Adolescents 14 to 18 years: 75 mcg
A single injection of vitamin K is also given at birth.
- Males 19 years and older: 120 mcg
- Females 19 years and older: 90 mcg
- Pregnant and breastfeeding females 14 to 18 years: 75 mcg
- Pregnant and breastfeeding females 19 years and older: 90 mcg
Because of the potential for side effects and interactions with medications,
dietary supplements should be taken only under the supervision of a
knowledgeable healthcare provider.
Vitamin K crosses the placenta and is also excreted in breast milk.
Therefore, pregnant women and women who are breast-feeding should consult a
healthcare provider before taking vitamin K supplements.
Those with an unusual metabolic condition called Glucose-6-phosphate
dehydrogenase (G6PD) deficiency should avoid vitamin K. Those with G6PD
deficiency experience a serious breakdown of red blood cells (called hemolysis)
when exposed to certain infections or medications, including vitamin K.
If you are currently being treated with any of the following medications, you
should not take vitamin K without first talking to your healthcare provider.
Antibiotics, particularly a class known as
cephalosporins, reduce the absorption of vitamin K. Extended use of antibiotics
may result in vitamin K deficiency because these drugs kill not only harmful
bacteria, but also beneficial, vitamin K-activating bacteria. This is
particularly a problem for people who already have low levels of vitamin K or
are at risk for deficiency (such as those who are malnourished, elderly, or
Preliminary evidence suggests that vitamin K3 (a
synthetic form of vitamin K) may enhance the chemotherapeutic effects of
doxorubicin. However, these results have not yet been demonstrated in people.
There is also some concern that vitamin K3 causes severe anemia in people. More
research is needed to assess if this synthetic form of vitamin K is safe and
Phenytoin interferes with the body's ability to use
vitamin K. Taking anticonvulsants (such as phenytoin) during pregnancy or while
breastfeeding may deplete vitamin K in newborns.
Vitamin K reduces the effects of the blood-thinning
medication warfarin, rendering the medication ineffective. Vitamin K should not
be taken while taking warfarin, and foods containing high amounts of vitamin K
should be avoided.
Weight Loss Products
Orlistat, a medication used for weight
loss and olestra, a substance added to certain food products, are both intended
to bind to fat and prevent the absorption of fat and the associated calories.
Because of their effects on fat, orlistat and olestra may also prevent the
absorption of fat-soluble vitamins such as vitamin K. Given this concern and
possibility, the Food and Drug Administration (FDA) now requires that vitamin K
and other fat soluble vitamins (namely, A, D, and E) be added to food products
containing olestra. How well vitamin K from such food products is absorbed and
used by the body is not clear. In addition, physicians who prescribe orlistat
add a multivitamin with fat soluble vitamins to the regimen.
The possibility of olestra or orlistat interfering with vitamin K absorption
is particularly important to know if you already have a vitamin K deficiency
(such as with malnourishment or poor fat absorption from cystic fibrosis) or if
you have a tendency to bleed (includign if you take the blood thinner warfarin).
On the other hand, the fact that vitamin K is now added to olestra-containing
food products is also significant if you should not be taking vitamin K (again,
for example, if you are on the blood thinner warfarin or you have a G6PD
X-rays and Radiation
X-rays and radiation can deplete vitamin
K levels and raise vitamin K requirements.
Each of the following may diminish vitamin K absorption and lead to reduced
levels in the body:
- Cholestyramine, one of a class of medications known as bile
acid sequestrants used to lower cholesterol
- Mineral oil laxatives
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|Review Date: April 2002|
|Reviewed By: Participants in the review process include: Jacqueline A. Hart, MD,
Department of Internal Medicine, Newton-Wellesley Hospital, Harvard University
and Senior Medical Editor Integrative Medicine, Boston, MA; Gary Kracoff, RPh
(Pediatric Dosing section February 2001), Johnson Drugs, Natick, Ma; Steven
Ottariono, RPh (Pediatric Dosing section February 2001), Veteran's
Administrative Hospital, Londonderry, NH; Margie Ullmann-Weil, MS, RD,
specializing in combination of complementary and traditional nutritional
therapy, Boston, MA. All interaction sections have also been reviewed by a team
of experts including Joseph Lamb, MD (July 2000), The Integrative Medicine
Works, Alexandria, VA;Enrico Liva, ND, RPh (August 2000), Vital Nutrients,
Middletown, CT; Brian T Sanderoff, PD, BS in Pharmacy (March 2000), Clinical
Assistant Professor, University of Maryland School of Pharmacy; President, Your
Prescription for Health, Owings Mills, MD; Ira Zunin, MD, MPH, MBA (July 2000),
President and Chairman, Hawaii State Consortium for Integrative Medicine,
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