Vitamin K is a group of structurally similar, fat-soluble vitamins the human body requires for complete synthesis of certain proteins that are required for blood coagulation the body needs for controlling binding of calcium in bones and other tissues. The vitamin K-related modification of the proteins allows them to bind calcium ions, which they cannot do otherwise. Without vitamin K, blood coagulation is seriously impaired and uncontrolled bleeding occurs. Low levels of vitamin K also weaken bones and promote calcification of arteries and other soft tissues.
Vitamin K1 was identified in 1929 by Danish scientist Henrik Dam when he investigated the role of cholesterol by feeding chickens a cholesterol-depleted diet. After several weeks, the animals developed hemorrhages and started bleeding. These defects could not be restored by adding purified cholesterol to the diet. A second compound, together with the cholesterol, apparently had been extracted from the food and this compound was called the coagulation vitamin. The new vitamin received the letter K because the initial discoveries were reported in a German journal, in which it was designated as Koagulationsvitamin.
Edward Adelbert Doisy of Saint Louis University did much of the research leading to the discovery of the structure and chemical nature of vitamin K. Dam and Doisy shared the 1943 Nobel Prize for medicine for their work on vitamin K (K1 and K2 published in 1939). [i]
The first published report of successful treatment with vitamin K of life threatening hemorrhage in a jaundiced patient with prothrombin (a blood plasma clotting protein) deficiency was made in 1938 by Smith, Warner and Brinkhouse.[ii]
Intestinal bacteria manufacture vitamin K in the body so deficiencies of this vitamin rarely result from poor diet. Pregnant women are sometimes given vitamin K before childbirth to prevent bleeding in newborn babies. Babies do not have enough intestinal bacteria to produce adequate amounts of vitamin K until about 2 weeks old.
Some people who may show a deficiency include those who suffer from liver damage, cystic fibrosis or inflammatory bowel diseases or have recently had abdominal surgeries. Others who may show a vitamin K deficiency are those on stringent diets, bulimics or people taking anticoagulants.
Another group at risk for deficiency are those subject to decreased production of vitamin K2 if taking broad-spectrum antibiotics, which can reduce vitamin K production in the gut by as much as 74% compared with those not taking these antibiotics.[iii] Those with chronic kidney disease are also at risk for vitamin K deficiency as well as the elderly through a reduction in vitamin K production.
Vitamin K is essential for blood clotting but as previously mentioned it is rare to have a deficiency of this vitamin resulting from poor diet.
Green leafy vegetables such as kale, spinach, cabbage, Romaine lettuce, collards and chard are all rich in vitamin K. Pork liver is also an excellent source. Other vegetables high in vitamin K are asparagus, broccoli, Brussels sprouts, parsley and mustard greens. There is little difference whether vegetables are eaten raw or cooked, other than amount. For instance 1 cup of raw broccoli is equal to 1 cup of cooked, but 1 cup of raw spinach is equal to ½ cup cooked.
An adequate intake of vitamin K for a 25-year-old male is 120 micrograms per day and for women is 90 micrograms. For children and adolescents it ranges at 15 – 100 micrograms per day.
As well as eating your green leafy vegetables for good health don’t forget regular visits to your chiropractor. Regular maintenance check-ups are just as important as a healthy diet – don’t wait until you hurt!
[i] MacCorquodale, D. W.; Binkley, S. B.; Thayer, S. A.; Doisy, E. A. (1939). “On the constitution of Vitamin K1”. Journal of the American Chemical Society 61 (7): 1928–1929.doi:10.1021/ja01876a510.
[ii] Warner, E. D.; Brinkhous, K. M.; Smith, H. P. (1938). “Bleeding Tendency of Obstructive Jaundice”. Proceedings of the Society of Experimental Biology and Medicine 37 (4): 628–630.doi:10.3181/00379727-37-9668P.
[iii] Conly, J; Stein K (1994). “Reduction of vitamin K2 concentrations in human liver associated with the use of broad spectrum antimicrobials”. Clinical and investigative medicine. Médecine Clinique et experimentale17 (6):531–539. PMID 7895417.