Vitamin K2 is the most biologically active member of the vitamin K family. Although the structurally similar K1 and K3 are not very usable inside the body, there is an exception. Your liver uses the vitamin K1 you take in with your food to make its very own K2. Vitamin K2 regulates many important functions of the body, such as blood clotting and bone metabolism.
You need only small amounts of vitamin K2, which are easy to reach if you follow a healthy diet. No specific dietary recommendations exist for vitamin K2, but the recommendations for the daily intake of K1 offer a blueprint, since the body transforms K1 into K2. Experts at the Linus Pauling Institute recommend 120 micrograms per day for adult men and 90 micrograms per day for women. The beneficial bacteria in your gut release small amounts of vitamin K2, but it is not clear how well it is absorbed or used. The richest dietary source of K2 is the Japanese dish natto. A 3.5-ounce serving provides 1,000 micrograms of vitamin K2, which is more than enough for a healthy adult. Other sources of K2 include sauerkraut, egg yolks, whole milk, butter and fatty goose, chicken or beef meat. Vitamin K1 is of plant origin and is abundant in dark green and leafy vegetables.
Certain groups are at high risk of vitamin K2 deficiency. Anticoagulant drugs, such as warfarin, act as antagonists of vitamin K2 and prevent it from fulfilling its biological role. If you are taking such medications, you may need to increase your dose of vitamin K2 to compensate for the loss. As a fat-soluble molecule, vitamin K requires sufficient amounts of dietary fat in the gut in order to be absorbed. A fat-free diet can result in reduced or no absorption of vitamin K. You can improve the absorption of vitamin K2 by adding a small quantity of healthy fat to your diet.
Newborn babies are in need of vitamin K because it cannot cross the placenta barrier very well and breast milk contains only small quantities of it. This concern does not hold true for formula-fed babies. Because a vitamin K deficiency can cause bleeding in newborns, the American Academy of Pediatrics and similar groups recommend that all newborns receive an injection of vitamin K. Breast-fed babies are likely to ingest 2 to 2.5 micrograms of vitamin K per day for the first year. After the first birthday, the recommended intake of vitamin K jumps to 30 micrograms per day and continues rising over the course of childhood until it reaches the adult dosage by the time the child is 19.
Vitamin K2 plays an important role in blood clotting. It acts as an activator of several proteins that trigger the formation of a clot. Individuals deficient in vitamin K2 show signs of impaired blood clotting, such as bleeding gums, heavy menstrual periods and frequent nosebleeds. Vitamin K2 also activates two of the proteins that transfer calcium to the bones. A study in the May 2006 medical journal "Haematologica" reports that vitamin K2 protects against myeloma and lymphoma, common blood-related cancer in the United States. In fact, K2 proves to have significant anticancer properties in more types of cancer, such as liver, stomach and lung malignancies.