Vitamin K: What is it good for?

Vitamin K: Function, Benefits, Sources and How Much You Need

Vitamin K is a fat-soluble vitamin, primarily involved in helping the blood clot, and production of blood clotting factors.

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What Does Vitamin K Do and what is it good for?

Vitamin K is a fat-soluble vitamin, primarily involved in helping the blood clot normally. Vitamin K plays a part in bone health through its role in the regulation of calcification of bone. The 'K' comes from the German word Koagulation, which means 'to clot'.

Forms of vitamin K

There are three forms of vitamin K – K1 and K2. K1 is also known as phylloquinone and phytomenadione. K1 is the prevailing source through diet

Green leafy vegetables are good sources of Vitamin K1. Vitamin K2 (menaquinones) is synthesised by bacteria found in your normal flora in the intestines2 and vitamin K3 (menadione) is a synthetic form.

How much vitamin K do I need?

Most people can get enough vitamin K simply by eating a balanced diet. Any excess vitamin K not required by your body is stored in the liver for future use3.

Vitamin K needs change dependent on a person's weight. Adults need 1µg a day of vitamin K for each kilogram they weigh. A simple example would be, someone who weighs 55kg would need 55μg of vitamin K a day, while a person who weighs 70kg would need 70µg a day. Any vitamin K that the body does not use is stored in the liver for future use by the body, so there is no need to consume vitamin K rich food daily3.

Any excess vitamin K not required by your body is stored in the liver for future use. Vitamin K is not usually used as a standalone food supplement, but it can be found in Seven Seas Perfect7 Man Plus.

Vitamin deficiencies are usually reasonably easy to correct, it is however important that a doctor diagnoses these deficiencies with a blood test so that they can recommend the appropriate required dietary changes or vitamin supplement.

Can I Take Too Much Vitamin K?

There is a lack of available evidence to know what the effects may be of taking high doses of vitamin K supplements each day. However, if you are concerned about vitamin K deficiency a healthcare professional will be able to advise.

Sources of vitamin K

Vitamin K is most found in green leafy vegetables such as lettuce, kale, mustard greens, parsley, spinach, Swiss chard, turnip greens, as well as vegetables such as broccoli, Brussel sprouts, cauliflower, and cabbage. It is also possible to obtain vitamin K from sources that are less rich in the vitamin. Other sources of vitamin K include vegetable oils and cereal grains, and smaller amounts can be found in meat and dairy foods.

People with clotting disorders, using warfarin for heart problems, or other conditions may need to change their diets to control the amount of vitamin K they take in6.

Interactions with vitamin K

There are a few commonly taken medications that can interfere with the effects of vitamin K such as antacids and blood thinners such as Warfarin. In fact, vitamin K is given to counteract excessive amounts of Warfarin in the body.

If you are on any medication please speak to a healthcare professional before taking any supplements or changing your diet.


  1. EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA); Scientific Opinion on the substantiation of health claims related to vitamin K and maintenance of bones (ID 123, 127, 128 and 2879), blood coagulation (ID 124 and 126), and function of the heart and blood vessels (ID 124, 125 and 2880) pursuant to Article 13(1) of Regulation (EC) No 1924/2006 on request from the European Commission. EFSA Journal 2009; 7 (9): 1228. [20 pp.]. doi:10.2903/j.efsa.2009.1228.

  2. Conly JM, Stein K. The production of menaquinones (vitamin K2) by intestinal bacteria and their role in maintaining coagulation homeostasis. Prog Food Nutr Sci. 1992 Oct-Dec;16(4):307-43.

  3. NHS. UK. 2020. Vitamins And Minerals - Vitamin K. [online] Available at: [Accessed 28 October 2020].

  4. Hathaway WE. Vitamin K deficiency. Southeast Asian J Trop Med Public Health. 1993;24 Suppl 1:5-9.

  5. Krasinski SD, Russell RM, Furie BC, Kruger SF, Jacques PF, Furie B. The prevalence of vitamin K deficiency in chronic gastrointestinal disorders. Am J Clin Nutr. 1985 Mar;41(3):639-43.

  6. NHS. UK. 2019. Warfarin: A Blood-Thinning Medicine To Treat And Prevent Blood Clots. [online] Available at: [Accessed 28 October 2020].

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