VITAMIN K OVERVIEW

Vitamin K Types

Vitamin K is a family of similar, fat-soluble, 2-methyl-1,4-naphthoquinones, that occur naturally as two chemically distinct forms called vitamin K1 and vitamin K2.

Vitamin K1 (Phylloquinone, phytonadione) is regarded as the major dietary source of Vitamin K, and in most people accounts for 90% of intakes, occurring naturally in plants, algae, and photosynthetic bacteria, green leafy vegetables, and vegetable oils.

Vitamin K1

Vitamin K2 or Menaquinone includes a range of related forms generally designated as menaquinone-n (MK-n) where n is the number of isoprenyl groups

Vitamin K2 as MK-4 is a short chain menaquinone and can be found predominately in meat, as well as in fermented products, certain types of cheese, butter, chicken, egg yolk and natto.

Vitamin K2 MK-4

Vitamin K2 as MK-7 is among the most popular long chain menaquinones and is primarily derived from our gut bacteria and, in addition, it can be found in lesser amounts in certain types of cheese, butter. In Japanese culture the fermented soybean food called Natto is an enormously rich source of the K2 vitamin as MK-7.

Vitamin K2 MK-7

Although K2 vitamins comprise only 10% of our total dietary vitamin K intake, they may form half of the total vitamin K absorbed due to the much better, nearly complete absorption and also significantly longer biological half-life of the long-chain menaquinones.

Three synthetic types of vitamin K are known: vitamins K3, K4, and K5. Vitamin K3 or menadione is considered to be a provitamin which can transform into the fat soluble Vitamin K forms in organism. Experimental cell studies were conducted with menadione, which shows strong growth inhibitory effect via oxidative stress on a variety of cancer cell lines, but is not recommended for human supplementation due to its toxicity.