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Vitamin K is an essential vitamin. It is one of the four fat-soluble vitamins, along with vitamin A, vitamin D, and vitamin E.

Vitamin K exists in three forms – K1, K2, and the less-known K3.

Vitamin K1, called phylloquinone, is quite easy to obtain in the diet. Good sources are green leafy vegetables such as kale, spinach, collard greens, parsley, broccoli, and brussels sprouts, as well as matcha tea. Unfortunately, although K1 is easy to obtain in the diet, its absorption is low.

Vitamin K2, called menaquinone, is found in fermented foods, especially in nato (a fermented soybean product). Eggs, butter, and liver are also good sources of K2.

Vitamin K2 may also be produced from our intestinal bacteria. However, most of the K2 produced in the intestine may not be available to be absorbed by our bodies. Also, long-term use of antibiotics that reduce these bacteria may diminish vitamin K synthesis in the colon.

What is the role of vitamin K in our body?
  • Vitamin K (in both forms K1 and K2) is best known for its role in blood clotting, or coagulation.  It helps to make certain proteins that are needed for blood clotting.

This, however, is only one of the functions that vitamin K has in our body.

  • Vitamin K2 also controls the concentration of calcium throughout the body. Its job is to make sure calcium gets to the right locations in the body, like the bones and teeth, instead of the soft tissues such as the kidneys. An adequate dietary intake of K2 helps the body to build strong bones and teeth.
  • Vitamin K2 plays an important role in cardiovascular health. Dietary intake of vitamin K2 might have a protective effect against cardiovascular disease.
  • Increased intake of vitamin K2 may also reduce the risk of prostate cancer. However, more research is needed.
What about deficiency?

Some typical vitamin K1 deficiency signs include:

  • easy bruising
  • bloody nose
  • excessive bleeding
  • heavy periods

Vitamin K2 deficiency may lead to:

  • weak bones and/or teeth
  • calcification of the arteries and other soft tissues

Unlike other fat-soluble vitamins, vitamin K is not stored well in our bodies, and significant amounts are excreted daily.

People with celiac disease and inflammatory bowel disease, for example, can not efficiently digest and absorb fat. Therefore they are more likely to develop vitamin K insufficiency or deficiency.

Also, people with cardiovascular disease, osteoporosis, tooth decay, or calcification of soft tissues, may need to pay more attention to their dietary K2 intake.

If you suspect that you are not obtaining enough vitamin K from your diet, it is a good idea to consult with your doctor about supplementation.

Vitamin K is often supplemented in combination with vitamin D since they both support bone health and are believed to work in synergy.

For your overall health and to prevent any health challenges associated with deficiency it is important to get adequate vitamin K from your diet. And the best way to do that is to consume more foods rich in vitamin K1 and K2 such as green vegetables and fermented foods, as well as to maintain a healthy digestive system.