Vitamin K was discovered by the Danish Scientist Henrik Dam in 1935, K resulting from 'Koagulation Vitamin', because this one is essential in blood coagulation. Unless you have a clinical problem regarding the absorption, you are safe and you cannot be deficient. Warfarin can act like an inhibitor of vitamin K (and all potent rat killers are vitamin K inhibitors because of this). Vitamin K has 2 natural forms, vitamin K1, plant based, phylloquinone, vitamin K2, synthesized by our microbiome (for humans and few selected animals), and lastly, vitamin K3, menadione, a synthetic compound used in animal nutrition. 

Food sources in the typical Western diet will provide 90% K1 and 10% K2, spinach, broccoli, lettuce, kale, fats, oil (canola oil). K1 in free form has an absorption rate of 80%, but if it is bound in foods, the absorption rate decreases. A mix of vegetable and fatty acids can improve the K1 absorption. K3 form was studied and it is no longer used, as it is damaging the liver. 

Metabolism and functions of vitamin K - this vitamin is absorbed in the middle and last part of the small intestine. Its absorption depends on the bile and pancreatic juices, and it is enhanced by the presence of dietary fats. It is deposited mainly in the liver, but present also in small quantities in the bones and heart. Vitamin K total pool is small, and vitamin K turnover is fast, but the human body can recycle vitamin K, allowing us to reused many times. Vitamin K is essential for biologically active forms of a range of proteins, called vitamin K dependent proteins. Through carboxylation, vitamin K is converted into glutamate and then the protein can bind Calcium. More than 12 proteins are affected by the vitamin K, many of them involved in coagulation and bone strength. 

The blood must flow freely and trigger clotting only if there is a rough edge in a blood vessel, like an artery cut. Proteins important in blood clotting are produced by the liver (prothrombin and fibrinogen) and released into the blood stream after. When clotting is triggered, the prothrombin become thrombin, activating the fibrinogen conversion into fibrin (fine threads joining together to create the blood clot). Vitamin K is needed so the liver can synthesize prothrombin from glutamate. If there is a vitamin K deficiency, the prothrombin production is slowed, impacting the coagulation. There are few other proteins involved in coagulation, that are activated by vitamin K, and the antagonist proteins, the ones slowing down coagulation are also assisted by vitamin K. 

The bones are formed by bone forming cells called osteoblasts, as they synthesize the osteocalcin with the support of vitamin D - calcitriol. Vitamin K is enabling the osteocalcin to bind minerals to the bone, as vitamin K will act as an coenzyme, converting three glutamate residues into osteocalcin, enabling bone remineralization. High vitamin K levels may protect against age-related bone fragility, osteoporosis and fractures. But, since leafy green vegetables (the main source of vitamin K) are also containing Calcium and Magnesium, we do not know if the protective effect is not linked to another nutrient or combination of nutrients. 

Next post will be about vitamin K deficiency. 

Yours truly, 

George

P.S. If you are Romanian, you can also publish your post link in the Publish0x Romanian Community Facebook group for others to read it. 

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