Vitamin K is a fat-soluble vitamin. This means it is stored in the liver and fatty tissues. Unlike the other fat-soluble vitamins, the body stores very little vitamin K. This makes regular dietary intake important. Bacteria in the large intestines help by making a range of vitamin K forms called menaquinones. Vitamin K is also made by plants (phylloquinone) and is found in green veggies, brussels sprouts, cabbage, and plant oils. The man-made vitamin K found in supplements is called menadione.
Vitamin K’s functions are:
Adequate Intake (AI)
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Blood does not clot normally in a person who does not get enough vitamin K. A deficiency is rare among healthy people. Symptoms of vitamin K deficiency are:
Vitamin K is stored in the body in small amounts. No tolerable upper intake level (UL) has been established for vitamin K. However, too much can cause the breakdown of red blood cells and liver damage. To be safe, a person should follow the intake guidelines based on age and gender
The medicines a person takes and the health problems they have may also play a role in how much vitamin K the body needs. A doctor or dietitian can help people make sure they are getting the right amount.
Foods that are high in vitamin K are:
Here are some ways to get more vitamin K:
Abbreviations: mcg = microgram; tbsp = tablespoon; tsp = teaspoon
Choose My Plate—US Department of Agriculture
Eat Right—Academy of Nutrition and Dietetics
Dietitians of Canada
Fat-soluable vitamins: A, D, E, and K. Colorado State University website. Available at: http://extension.colostate.edu/topic-areas/nutrition-food-safety-health/fat-soluble-vitamins-a-d-e-and-k-9-315. Accessed August 26, 2020.
Phytonadione. EBSCO DynaMed website. Available at:https://www.dynamed.com/drug-monograph/phytonadione. Accessed August 26, 2020.
Vitamin K. EBSCO Natural and Alternative Treatments website. Available at: http://www.ebscohost.com/academic/natural-alternative-treatments. Accessed August 26, 2020.
Vitamin K. The Linus Pauling Institute website. Available at: http://lpi.oregonstate.edu/mic/vitamins/vitamin-K. Accessed August 26, 2020.
Last reviewed March 2020 by EBSCO Medical Review BoardDianne Scheinberg Rishikof MS, RD, LDN Last Updated: 3/2/2021