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 bleedings.4 This could not be stopped by adding cholesterol to the diet, so Dam postulated that – together with fat – there had to be another compound in the diet that prevented the bleedings. After years of research he found a factor in hempseed that 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.
This monumental discovery of Vitamin K earned Professors Henrik Dam and Edward Doisy the Nobel Prize in 1943.
Esmon et al. published the mechanism of action of vitamin K and identified the vitamin K cycle as vital for the activity of carboxylase enzyme.
Vermeer et al. published that vitamin K deficiency influences the ratio of serum uncarboxylated to carboxylated osteocalcin.
Sokoll et al. published that the US dietary vitamin K intake is not sufficient to fully carboxylate osteocalcin.
Schurgers et al. published that inhibition of vitamin K-dependent carboxylation of MGP promotes vascular calcification.
Tsugawa et al. published that MK-7 is the vitamin K form found in serum of women with reduced risk of bone fractures. Later that year Ikeda et al. published that intake of MK-7 is associated with reduced bone loss in post menopausal women in a population-based study (JPOS study).
Schurgers et al. used rats to demonstrate that that arterial calcification and the resulting decreased arterial distensibility are reversible by high intake of vitamin K.
Nimptsch et al. published a large population-based study showing that consuming dairy products containing higher menaquinones like MK-7 reduces the risk of prostate cancer substantially. No such reduction was observed with vitamin K1-containing food. Later, van Summeren et al. showed that a better vitamin K status was associated with more pronounced increase in bone mass in healthy children.
Beulens et al. found among 564 post-menopausal women that intake of Vitamin K2 – but not vitamin K1 – was associated with reduced coronary calcification, and that adequate Vitamin K2 intake could be important for prevention of cardiovascular disease. Shortly thereafter van Summeren et al. demonstrated that modest MK-7 supplementation increases circulating concentrations of MK-7 and increases osteocalcin carboxylation in healthy children, while Gast et al. found that a high menaquinone intake reduces the incidence of coronary heart disease.
Westenfeld et al. confirmed that most hemodialysis patients have a functional vitamin K deficiency. More importantly, they found that inactive MGP levels can be decreased markedly by daily Vitamin K(2) supplementation.
Knapen et al. showed that after three years of supplementation of 180 mcg Vitamin K2 as MK-7 (MenaQ7®) daily, improvements in both bone mineral content and bone mineral density were statistically significant in the MenaQ7® group. Moreover, bone strength was statistically improved. Later that year Theuwissen et al. established the vitamin K status across age groups based on circulating levels of ucOC and dp-ucMGP, i.e. markers for the vitamin K status of bone and the vasculature, respectively. Accordingly, the study classified healthy children and adults above 40 years as groups with prominent vitamin K deficiency and thus appropriate groups for vitamin K supplementation.
Knapen et al. published the first double-blind, randomized, intervention trial where the results confirm that Vitamin K2 intake is linked to cardiovascular risk. Researchers found that, after three years of daily supplementation with 180 mcg Vitamin K2 as MK-7 (as MenaQ7®), it not only inhibited age-related stiffening of the artery walls, but also made a statistically significant improvement of vascular elasticity, especially in women having high arterial stiffness. To date, the effects of increased menaquinone intake on markers of vascular health have been investigated using predominantly food supplements. Therefore, Knapen et al. sought to study the effects of a menaquinone-fortified yogurt drink (as MenaQ7®) on vitamin K status and markers of vascular health in healthy men and postmenopausal women. Results showed MK-7 was efficiently absorbed from the fortified yogurt drink, improving vitamin K status, which contributed to improved cardiovascular health.