Vitamin KSkip to the navigation
Vitamin K is needed for proper bone formation and blood clotting. In both cases, vitamin K does this by helping the body transport calcium . Vitamin K is used by doctors when treating an overdose of the drug warfarin . Also, doctors prescribe vitamin K to prevent excessive bleeding in people taking warfarin but requiring surgery.
There is promising preliminary evidence that vitamin K2 (not vitamin K1), may improve a group of blood disorders known as myelodysplastic syndromes,1 which carry a significantly increased risk of progression to acute myeloid leukemia.
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Our proprietary "Star-Rating" system was developed to help you easily understand the amount of scientific support behind each supplement in relation to a specific health condition. While there is no way to predict whether a vitamin, mineral, or herb will successfully treat or prevent associated health conditions, our unique ratings tell you how well these supplements are understood by the medical community, and whether studies have found them to be effective for other people.
For over a decade, our team has combed through thousands of research articles published in reputable journals. To help you make educated decisions, and to better understand controversial or confusing supplements, our medical experts have digested the science into these three easy-to-follow ratings. We hope this provides you with a helpful resource to make informed decisions towards your health and well-being.
3 Stars Reliable and relatively consistent scientific data showing a substantial health benefit.
2 Stars Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.
1 Star For an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support.
This supplement has been used in connection with the following health conditions:
How It Works
How to Use It
The recommended dietary allowance for vitamin K is about 1 mcg per 2.2 pounds of body weight per day or about 65 to 80 mcg per day for most adults.2 This level of intake may be achieved by consuming adequate amounts of leafy green vegetables. However, studies have shown that many men and women aged 18 to 44 years ingest less than the recommended amount of vitamin K.3 , 4
Where to Find It
Leafy green vegetables, such as spinach, kale, collards, and broccoli, are the best sources of vitamin K. The greener the plant, the higher the vitamin K content.5 Other significant dietary sources of vitamin K include soybean oil, olive oil, cottonseed oil, and canola oil.6
A vitamin K deficiency, which causes uncontrolled bleeding, is rare, except in people with certain malabsorption diseases . However, there are reports of severe vitamin K deficiency developing in hospitalized patients who had poor food intake and were receiving antibiotics.7 All newborn infants receive vitamin K to prevent deficiencies that sometimes develop in breast-fed infants.
Best Form to Take
Vitamin K comprises a group of structurally related compounds, including vitamin K1 (the major form found in plants), vitamin K2 (including menaquinone-4 [MK-4], also known as menatetrenone; and menaquinone-7 [MK-7]), and vitamin K3. Vitamin K supplements contain vitamin K1, MK-4, or MK-7. While there is some evidence indicating that MK-7 raises vitamin K blood levels the most, there is insufficient clinical research to indicate that this form of the vitamin is more effective than the other forms. MK-4 given in very large amounts has been used successfully in certain conditions but it is not clear whether the benefits are due to its vitamin K activity or to some other biological function.8
Interactions with Supplements, Foods, & Other Compounds
Vitamin K facilitates the effects of calcium in building bone and proper blood clotting.
Interactions with Medicines
Certain medicines interact with this supplement.
Types of interactions: Beneficial Adverse Check
Replenish Depleted Nutrients
Reduce Side Effects
Potential Negative Interaction
The Drug-Nutrient Interactions table may not include every possible interaction. Taking medicines with meals, on an empty stomach, or with alcohol may influence their effects. For details, refer to the manufacturers' package information as these are not covered in this table. If you take medications, always discuss the potential risks and benefits of adding a supplement with your doctor or pharmacist.
Allergic reactions to vitamin K injections have been reported on rare occasions.9
1. Miyazawa K, Nishimaki J, Ohyashiki K, et al. Vitamin K2 therapy for myelodysplastic syndromes (MDS) and post-MDS acute myeloid leukemia: information through a questionnaire survey of multi-center pilot studies in Japan. Leukemia 2000;14:1156-7 [letter].
2. Food and Nutrition Board, National Research Council. Recommended Dietary Allowances, 10th ed. Washington DC: National Academy Press, 1989.
3. Booth SL, Suttie JW. Dietary intake and adequacy of vitamin K. J Nutr 2000;130(1S Suppl):785-8.
4. Booth SL, Webb DR, Peters JC. Assessment of phylloquinone and dihydrophylloquinone dietary intakes among a nationally representative sample of US consumers using 14-day food diaries. J Am Diet Assoc 1999;99:1072-6.
5. Kodaka K, Ujiie T, Ueno T, Saito M. Contents of vitamin K1 and chlorophyll in green vegetables. J Jpn Soc Nutr Food Sci 1986;39:124-6.
6. Booth SL, Centurelli MA. Vitamin K: a practical guide to the dietary management of patients on warfarin. Nutr Rev 1999;57:288-96 [review].
7. Pineo GF, Gallus AS, Hirsh J. Unexpected vitamin K deficiency in hospitalized patients. Can Med Assoc J 1973;109:880-3.
8. Gaby, AR. Nutritional Medicine. Concord, NH: Fritz Perlberg Publishing, 2011.
9. Wong DA, Freeman S. Cutaneous allergic reaction to intramuscular vitamin K1. Australas J Dermatol 1999;40:147-52.
Last Review: 06-05-2015
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The information presented by Healthnotes is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires December 2017.
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