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Table of Contents > Supplements > Vitamin K
Vitamin K
Also Known As:  menaphthone, menaquinone, phylloquinone, phytonadione, phytoquinone
Dietary Sources
Available Forms
How to Take It
Possible Interactions
Supporting Research


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 deficiency include:

  • 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 Interactions)
  • Ongoing or significant diarrhea (particularly in breast fed infants)
  • Long-term use of total parenteral nutrition (TPN; nutrition provided intravenously)
  • 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:

Excessive Bleeding
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.

Snake Bite
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.

Cystic Fibrosis
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 antibiotics.

Kidney Stones
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.)

Body Odor
Chlorophyll (a water-soluble source of vitamin K in plant foods) helps control body, fecal, and urinary odor.

Skin Wounds
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.

Dietary Sources

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.

Available Forms

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 below:


  • 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.

Possible Interactions

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 taking warfarin).

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 useful.

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 deficiency).

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:

  • Aspirin
  • Cholestyramine, one of a class of medications known as bile acid sequestrants used to lower cholesterol
  • Mineral oil laxatives

Supporting Research

Behrman RE, Kliegman RM, Jenson HB, eds. Nelson Textbook of Pediatrics. 16th ed. Philadelphia, PA:WB Saunders Co. 2000:188, 526-527, 1164.

Bell RG, Sadowski JA, Matschiner JT. Mechanism of action of warfarin. Warfarin and metabolism of vitamin K1. Biochem. 1972;11:1959-1961.

Berkow R, Fletcher AJ eds. Vitamin K. In The Merck Manual. 16th ed. Rahway, N.J.: Merck & Co., Inc.1992:966-968.

Booth SL, Centurelli MA. Vitamin K: a practical guide to the dietary management of patients on warfarin. Nutr Rev. 1999;57(9 Pt 1):288-293.

Booth SL, Charnley JM, Sadowski JA, Saltzman E, Bovill EG, Cushman M. Dietary vitamin K1 and stability of oral anticoagulation: proposal of a diet with constant vitamin K1 content. Thromb Haemost. 1997;77(3):504-509.

Breen GA, St. Peter WL. Hypoprothrombinemia associated with cefmetazole. Ann Pharmacother. 1997;31(2):180-184.

Crowther MA, Julian J, McCarty D, et al. Treatment of warfarin-associated coagulopathy with oral vitamin K: a randomized controlled trial. Lancet. 2000;356(9241):1551-1553.

Fauci AS, Braunwald E, Isselbacher KJ, et al. eds. Harrison's Principles of Internal Medicine. 14th ed. New York, NY. McGraw-Hill. 1998:739, 741, 1450, 1708.

Feskanich D, Weber P, Willett WC, Rockett H, Booth SL, Colditz GA. Vitamin K intake and hip fractures in women: a prospective study. Am J Clin Nutr. 1999;69:74-79.

Harrell CC, Kline SS. Vitamin K—supplemented snacks containing olestra: implication for patients taking warfarin [letter]. JAMA. 1999;282(12):1133-1134.

Hathcock, JN. Metabolic mechanisms of drug-nutrient interactions. Fed Proc. 1985;44(1):124-129.

Hey E. Effect of maternal anticonvulsant treatment on neonatal blood coagulation. Arch Dis Child Fetal Neonatal Ed. 1999;81(3):F208-210.

Huilgol VR, Markus SL, Vakil NB. Antibiotic-induced iatrogenic hemobilia. Am J Gastroenterol. 1997;92(4):706-707.

Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, DC: National Academy Press; 2001. Accessed on February 25, 2002 at

Iwamoto I, Kosha S, Noguchi S, Murakami M, Fujino T, Douchi T, et al. A longitudinal study of the effect of vitamin K2 on bone mineral density in postmenopausal women: a comparative study with vitamin D3 and estrogen-progestin therapy. Maturitas. 1999;31(2):161-164.

Jenkins ME, Gottschlich MM, Kopcha R, Khoury J, Warden GD. A prospective analysis of serum vitamin K in severely burned pediatric patients. J Burn Care Rehabil.1998;19(1 Pt 1):75-81; discussion 73-74.

Keith DA, Gundberg CM, Japour A, et al. Vitamin-K dependent proteins and anticonvulsant medication. Clin Pharmacol Ther. 1983;34(4):529-532.

Knodel LC, Talbert RL. Adverse effects of hypolipidaemic drugs. Med Toxicol. 1987;2(1):10-32.

Kohlmeier M, Saupe J, Shearer MJ, Schaefer K, Asmus G. Bone health of adult hemodialysis patients is related to vitamin K status. Kidney Int. 1997;51:1218-1221.

Koonsvitsky BP, Berry DA, Jones MB, et al. Olestra affects serum concentrations of alpha-tocopherol and carotenoids but not vitamin D or vitamin K status in free-living subjects. J Nutr. 1997;127(8 Suppl):1636S-1645S.

Krummel D, Kris-Etherton P. Nutrition in Women's Health. Gaithersburg, Md: Aspen Publishers; 1996:434-435.

Lubetsky A, Dekel-Stern E, Chetrit A, Lubin F, Halkin H. Vitamin K intake and sensitivity to warfarin in patients consuming regular diets. Thromb Haemost. 1999;8:396-399.

Matsui MS, Rozovski, SJ. Drug-nutrient interaction. Clin Ther. 1982;4(6):423-440.

Nulman I, Laslo D, Koren G. Treatment of epilepsy in pregnancy. Drugs. 1999;57(4):535-544. Published erratum appears in Drugs. 1999;57(6):870.

Nutrients and Nutritional Agents. In: Kastrup EK, Hines Burnham T, Short RM, et al, eds. Drug Facts and Comparisons. St. Louis, Mo: Facts and Comparisons; 2000.

Ong T, Whong WZ, Stewart J, and Brockman HE. Chlorophyllin: a potent antimutagen against environmental and dietary complex mixtures. Mutation Research. 1986;173:111-115.

Parekh H, Chavan S, Advani S, Chitnis M. Single and combination treatment with vitamin K3 and adriamycin: in vitro effects on cell survival and DNA damage in human chronic myeloid leukemia cells. Sel Cancer Ther. 1991;7(3):127-135.

Prince DM, Welshenbach MA. Olestra: a new food additive. J Am Diet Assoc. 1998;98(5):565-569.

Rashid M, Durie P, Andrew M, et al. Prevalence of vitamin K deficiency in cystic fibrosis. Am J Clin Nutr. 1999;70(3):378-382.

Schlagheck TG, Riccardi KA, Zorich NL, Torri SA, Dugan LD, Peters JC. Olestra dose response on fat-soluble and water-soluble nutrients in humans. J Nutr. 1997;127(8 Suppl):1646S-1665S.

Segel GB. Enzymatic defects: glucose-6-phosphate dehydrogenase (G6PD) and related deficiencies. In Behrman RE, Kliegman RM, Jenson HB, eds. Nelson Textbook of Pediatrics. 16th ed. Philadelphia, PA:WB Saunders Co; 2000:1489-1491.

Shils ME, Olson JA, Shike M, Ross CA, eds. Modern Nutrition in Health and Disease. 9th ed. New York, NY: Lippincott, Williams & Wilkins; 1999.

Shiraki M, Shiraki Y, Aoki C, Miura M. Vitamin K2 (menatetrenone) effectively prevents fractures and sustains lumbar bone mineral density in osteoporosis. J Bone Miner Res. 2000;15(3):515-523.

Suzuki K, Fukushima T, Meguro K, et al. Intracranial hemorrhage in an infant owing to vitamin K deficiency despite prophylaxis. Childs Nerv Syst. 1999;15(6-7):292-294.

Tamatani M, Morimoto S, Nakajima M, et al. Decreased circulating levels of vitamin K and 25-hydroxyvitamin D in osteopenic elderly men. Metabolism. 1998;47:195-199.

Thornquist MD, Kristal AR, Patterson RE, et al. Olestra consumption does not predict serum concentrations of carotenoids and fat-soluble vitamins in free-living humans: early results from the sentinel site of the olestra post-marketing surveillance study. J Nutr. 2000;130(7):1711-1718.

Weber P. The role of vitamins in the prevention of osteoporosis--a brief status report. Int J Vitam Nutr Res. 1999;69(3):194-197.

Weibert RT, Le DT, Kayser SR, et al. Correction of excessive anticoagulation with low-dose oral vitamin K1. Ann Intern Med. 1997;126(12):959-962.

Wilson DC, Rashid M, Durie PR, et al. Treatment of vitamin K deficiency in cystic fibrosis: effectiveness of a daily fat-soluble vitamin combination. J Pediatr. 2001;138(6):851-855.

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, Honolulu, HI.

Copyright © 2004 A.D.A.M., Inc

The publisher does not accept any responsibility for the accuracy of the information or the consequences arising from the application, use, or misuse of any of the information contained herein, including any injury and/or damage to any person or property as a matter of product liability, negligence, or otherwise. No warranty, expressed or implied, is made in regard to the contents of this material. No claims or endorsements are made for any drugs or compounds currently marketed or in investigative use. This material is not intended as a guide to self-medication. The reader is advised to discuss the information provided here with a doctor, pharmacist, nurse, or other authorized healthcare practitioner and to check product information (including package inserts) regarding dosage, precautions, warnings, interactions, and contraindications before administering any drug, herb, or supplement discussed herein.

  Uses of this Supplement
Bone Cancer
Cystic Fibrosis
Kidney Stones
Myeloproliferative Disorders
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