Vitamin K is an important nutrient for human health and participates in a wide range of reactions and mechanisms in your body.  Unlike the many water soluble vitamins we are familiar with (Vit C, Vit B, etc.)  Vitamin K is a  fat soluble nutrient that may need to be supplemented in modern day diets, like another famous fat soluble vitamin, Vitamin D.  Research indicates that both of these vitamins are deficient in our general population.   Because of the widespread prescription of “blood thinners”  much of what the general public has heard about Vitamin K its role in blood clotting.   It is often portrayed as a “blood thickener” that opposes prescription drugs (erroneously) labeled “blood thinners”. It is therefor portrayed as “bad” and patients on “blood thinners” are routinely warned to “stay away from Vitamin K”.   But, like many things, the real story isn’t that simplistic.  It is true that Vitamin K is involved in blood clotting.  In fact, blood clotting can not occur without adequate Vitamin K and it is considered a major rate limiting factor in proper coagulation; you can’t make platelets without Vitamin K.  However, coagulation, though much maligned as of late, is an important part of proper blood regulation and keeps blood from leaking out of the vessels indiscriminately.  You may have noticed, people on “blood thinners”, including baby aspirin, often have what appears to be bruises on their arms and legs.  Many of these people say they don’t know how they got the bruise but that it just popped up spontaneously for no known reason, often appearing after sleep.  Do you think this is “good” or “normal”?  I suggest not.  It is rather an indication that there is too much potential for spontaneous bleeding and make us question whether bleeding  is just restricted to the skin or whether it is happening other places internally….like your internal organs or brain.  

Meanwhile, Vitamin K is not a “blood thickener” on its own but merely supports the clotting mechanism when another part of the clotting cascade gives the signal to initiate the clotting response.  This mechanism is similar whether the stimulus is a cut on the skin or something more internal, like the need to prevent blood leaking from the vessels.  Without proper regulation of this mechanism spontaneous internal leaking can create blood leaking into the brain, which technically is called an aneurism, which leads to the events we call a TIA or hemmoragic “stroke”.  Drugs that are anticoagulants, typically called “blood thinners” tend to work to oppose the mechanism of vitamin K in the clotting process.  So in this case an above normal level of Vitamin K  may be able to offset the action of the drugs, though not a certainty.  However, doctors who are prescribing “blood thinners” give an across-the-board warning patients to stay away from Vit K supplements.  But where do we get Vitamin K from anyway?  Like everything else, it comes from our food.  It is prevalent in certain foods, particularly green leafy vegetables, which no one tells patients to stay away from, as well as olive oil, which is recommended as a dietary staple by many cardiologists.  Since most people are not regularly eating green leafy vegetables in sufficient amount the population tends to have low Vitamin K.  But a deficiency of Vitamin K can adversely affect body processes other than coagulation.  The process of bone rebuilding and other aspects of calcium regulation is highly dependent on Vitamin K.  Vitamin D is frequently touted as essential to bone building. But its primary role is in getting calcium out of the digestive tract and into the blood stream, whereas  Vitamin K is responsible for getting calcium out of the blood and into the bone.  Additionally, Vitamin K plays an important role in energy production in the mitochondria, and is important in heart, liver, and brain health.  There was a reason grandma said “Eat your vegetables”.