Written by Keith Pearson, PhD, RD on September 15, 2017

Vitamin K is well-known for its role in blood clotting.

But you may not know that its name actually refers to a group of several vitamins that provide health benefits far beyond helping your blood clot.

This article will review the differences between the two main forms of vitamin K found in the human diet: vitamin K1 and vitamin K2.

You’ll also learn which foods are good sources of these vitamins and the health benefits you can expect from eating them.

What Is Vitamin K?

Vitamin K is a group of fat-soluble vitamins that share similar chemical structures.

Vitamin K was accidentally discovered in the 1920s and 1930s after restricted diets in animals led to excessive bleeding (1Trusted Source).

Although there are several different types of vitamin K, the two most often found in the human diet are vitamin K1 and vitamin K2.

Vitamin K1, also called phylloquinone, is mostly found in plant foods like leafy green vegetables. It makes up about 75–90% of all vitamin K consumed by humans (2Trusted Source).

Vitamin K2 is found in fermented foods and animal products, and is also produced by gut bacteria. It has several subtypes called menaquinones (MKs) that are named by the length of their side chain. They range from MK-4 to MK-13.

Food Sources of Vitamin K1

Vitamin K1 is produced by plants. It is the predominant form of vitamin K found in the human diet.

The following list includes several foods that are high in vitamin K1. Each value represents the amount of vitamin K1 in 1 cup of the cooked vegetable (3Trusted Source).

  • Kale: 1,062 mcg
  • Collard greens: 1,059 mcg
  • Spinach: 889 mcg
  • Turnip greens: 529 mcg
  • Broccoli: 220 mcg
  • Brussels sprouts: 218 mcg

Food Sources of Vitamin K2

Food sources of vitamin K2 vary by subtype.

One subtype, MK-4, is found in some animal products and is the only form not produced by bacteria. Chicken, egg yolks and butter are good sources of MK-4.

MK-5 through MK-15 are forms of vitamin K2 with longer side chains. They are produced by bacteria and often found in fermented foods.

Natto, a popular Japanese dish made from fermented soybeans, is particularly high in MK-7.

Certain hard and soft cheeses are also good sources of vitamin K2, in the form of MK-8 and MK-9. Additionally, a recent study discovered several pork products contain vitamin K2 as MK-10 and MK-11 (4Trusted Source).

The vitamin K2 content for 3.5 ounces (100 grams) of several foods is listed below (4Trusted Source, 5Trusted Source, 6Trusted Source).

  • Natto: 1,062 mcg
  • Pork sausage: 383 mcg
  • Hard cheeses: 76 mcg
  • Pork chop (with bone): 75 mcg
  • Chicken (leg/thigh): 60 mcg
  • Soft cheeses: 57 mcg
  • Egg yolk: 32 mcg