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:
- Making proteins that stop bleeding
- Helping the body make other proteins needed for blood, bones, and kidneys
Adequate Intake (AI)
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Vitamin K Deficiency
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:
- Easy bruising and bleeding—nosebleeds, bleeding gums, blood in the urine, blood in the stool, or heavy menstrual bleeding
- Bleeding in the skull in infants
Vitamin K Safety
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.
Major Food Sources
Foods that are high in vitamin K are:
- Brussels sprouts
- Collard greens
- Bib lettuce
- Green pepper
- Canola and soybean oils
Tips to Increase Vitamin K Intake
Here are some ways to get more vitamin K:
- Slice an avocado. Add a little balsamic vinegar and pepper, and scoop out for a snack. Or, mash the avocado and mix with chopped tomatoes and red onions for a refreshing salsa.
- Pack a kiwi and spoon for an afternoon snack. The insides of the kiwi can be scooped out and eaten from this natural and easy container.
- Steam one-half cup broccoli or Brussels sprouts, add lemon juice (1 tbsp), pre-chopped garlic (1 tsp), and Dijon mustard (1 tbsp). Or add broccoli to lasagna or hot dish.
- Mix 2 (10-ounce) packages of frozen chopped spinach, thawed, well drained, one 8-ounce package of softened low-fat cream cheese, one-fourth cup milk, and 1 tsp lemon pepper until well blended. Spoon into a 1-quart casserole dish and sprinkle with one-third cup crushed crackers or seasoned croutons. Bake at 350 °F (degrees Fahrenheit); 177 °C (degrees Celsius) until thoroughly heated (about 25-30 minutes.).
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