Vitamin K

Vitamin K

Vitamin K is a fat soluble vitamin that is stored in the fat cells (known as adipose tissue), liver, and pancreas. It has many functions, and research at the Mayo Cancer Center in Minnesota found that "the risk of developing non-Hodgkin lymphomas—cancer of the immune system—was approximately 45% lower for those whose vitamin K intake was in the top quarter, vs. those whose intake of the vitamin was in the bottom quarter."


Vitamin K deficiency is uncommon in healthy adults because it is found in a variety of foods and is conserved through a process called the ‘vitamin K cycle’.

There are three forms of vitamin K:

  • Vitamin K1 is the dietary form found in green leafy vegetables
  • Vitamin K2 is naturally synthesized by normal colon bacteria
  • Vitamin K3 is a major contributor in the blood clotting process


Most people have no idea what vitamin K's function is in the body:

  • It regulates blood clotting, occurring when any injury results in a tear in a blood vessel.
  • It transports calcium out of the blood vessels and into those bones deficient of the mineral.
  • It prevents the calcification of organs and other soft tissues.
  • It promotes healthy bones and reduces fractures, especially among postmenopausal women.

Food Sources

The vitamin is predominately found in green leafy vegetables such as spinach, asparagus, kale and broccoli; and in a small group of vegetable oils (such as olive, cottonseed, soybean, and canola oils).  A liquid form can be found in water-soluble chlorophyll, and vitamin K is also enriched in olestra-containing foods*.


Although vitamin K deficiencies are rare, certain diseases can interfere with vitamin K's production cycle:

  • Liver disease,
  • Gallbladder disease such as fat malabsorption syndrome,
  • Platelet disorders,
  • Chrohn's disease, and
  • Celiac disease

Drug Interactions

Most individuals receive their daily recommended amount of vitamin K through diet and taking a daily multi-vitamin.  However, too much vitamin K, either in dietary form or in supplements, can interfere with the medicinal effects of certain medications:

  • anticoagulants like warfarin, and
  • anticonvulsants like isoniazid

Interference with Vitamin K Absorption

On the other hand, some medications can interfere with the body's ability to utilize vitamin K. These medications interfere with the absorption of dietary fats and therefore, may block the proper absorption of fat-soluble vitamins (such as vitamins K, A, D, and E):

  • Phenytoin,
  • Orlistat
  • Olestra*
  • Cholestyramine
  • Colestipol

Balancing the medicinal and nutritional needs of the body can often be a delicate process.  Therefore, always consult with your physician before taking any self-help remedies.


*Olestra is a substance added to many weight-loss products because it blocks absorption of fat. The substance may also reduce the body's ability to absorb fat-soluble vitamins. The Food and Drug Administration now requires that vitamin K as well as the other fat-soluble vitamins (A, D, and E) be added to food products containing olestra.

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Linda Mundorff, MPH, MSN, ND, RN, CNC, CTN has worked in health care for over 25 years as a registered nurse, health educator, associate professor, and a naturopathic doctor. She holds several degrees in health education, public health, nursing, and naturopathy. She is a certified nutritional consultant and a board certified traditional naturopath. Dr. Mundorff is the author of several books, including Memories Of My Sister: Dealing with Sudden Death, Medical Terminology: A Student Workbook. Her latest, Take Control: A Guide to Holistic Living, is an innovative health guide, which helps the reader learn how to regain control of their health by discovering the practical effectiveness of combining alternative and modern medicine.