Vitamin K

Vitamin K plays a key role in blood clotting. Without this essential vitamin, there’s a higher risk of excessive bleeding, which could lead to death.


Vitamin K is actually a group of fat-soluble compounds divided into two main groups:

  • Vitamin K1 (phylloquinone). Found in plant-sourced foods, phylloquinone is the main form of vitamin K in the diet (50Trusted Source).
  • Vitamin K2 (menaquinone). This variety of vitamin K is found in animal-sourced foods and fermented soy products, like natto. Vitamin K2 is also produced by gut bacteria in the colon (51Trusted Source52Trusted Source).

Additionally, there are at least three synthetic forms of vitamin K. These are known as vitamin K3 (menadione), vitamin K4 (menadiol diacetate), and vitamin K5.

SUMMARYVitamin K is a family of compounds. The main dietary forms are vitamin K1, found in plant foods, and vitamin K2, found in animal-derived foods and fermented soy products.

Role and function of vitamin K

Vitamin K plays an essential role in blood clotting. In fact, the “K” stands for “koagulation,” the Danish word for coagulation, which means clotting.

But vitamin K has other functions as well, including supporting bone health and helping prevent the calcification of blood vessels, potentially reducing the risk of heart disease (53Trusted Source).

SUMMARYVitamin K is vital for blood clotting and supports bone health.

Dietary sources

The best dietary sources of vitamin K1 (phylloquinone) are leafy green vegetables, while vitamin K2 (menaquinone) is mainly found in animal-sourced foods and fermented soy products.

The table below shows some of the main sources of vitamin K1 and the amounts found in 3.5 ounces (100 grams) of these foods