History

Vitamin K was discovered in 1929. The Danish scientist, Henrik Dam and colleagues, were investigating the role of dietary cholesterol by feeding chickens a diet without fat. After several weeks the animals started to suffer from frequent bleedings¹. This could not be stopped by adding cholesterol to the diet. So he postulated that – together with fat - there had to be another compound in the diet which prevented the bleedings. After years of research he found a factor in hempseed which prevented bleeding; and decided to call it the coagulation vitamin. It was designated in German as Koagulations vitamin and that is how the new vitamin got the letter K.
Nobel Price
The discovery of vitamin K was awarded the Nobel Prize in 1943. It was shared by Professors Henrik Dam and Edward Doisy.

Henrik Dam and Edward Doisy

1929 – Dam discovers that young birds fed a fat-deficient diet experience lengthened blood clotting time, anemia and hemorrhage. He postulates that there had to be a missing fat-soluble factor not previously known²

1934 – Dam and Schønheyder identify a factor in hempseed that prevents bleeding. Dam called it vitamin K from "Koagulations-Vitamin" in German³. He also found vitamin K in other vegetables and in animal liver

1938 – Almquist et al show that vitamin K is formed also in bacteria in the intestinal canal⁴

1939 – Doisy et al succeed in determining the chemical structure of vitamin K as well as to synthesize vitamin K

1943 – Dam and Doisy shared the Nobel Prize in medicine for their discovery of vitamin K

1974 – Stenflo and Nelsestuen discover that prothrombin – one of the important coagulation factors- contains the unusual amino acid γ-carboxy glutamic acid (Gla) in the vitamin K-dependent region of the molecule. This led to the understanding of how vitamin K could contribute to the activation of coagulation factors^{5, 6}

1975 – Esmon et al discover a vitamin K-dependent protein carboxylation reaction in the liver⁷

1983 – Price et al describe Matrix Gla-protein (MGP); the strongest vitamin K-dependent inhibitor of tissue calcification presently known⁸

1997 – Lou et al demonstrate the importance of MGP for vascular health by using MGP-deficient animals⁹

2004 – Geleijnse et al publish a population-based study demonstrating that high dietary intake of vitamin K2 influences cardiovascular health and reduced cardiovascular mortality. In this study dietary vitamin K2 appeared to be superior to vitamin K1

2007 – Schurgers et al show that natural vitamin K2 as Menaquinone-7 (MK-7) is the most bioavailable, bioactive and longest lasting form of vitamin K¹⁰

2008 – Gast el al publish another large population study confirming that natural dietary vitamin K2 is correlated to improved cardiovascular health. Intake of vitamin K1 has no effect, while the benefits are specifically associated with the longer menaquinones MK-7, MK-8 and MK-9