The following paragraphs are provided by USANA, The Cellular Nutrition Company
Vitamin K was discovered completely by chance.
In 1929, scientist Henrik Dam discovered Vitamin K and it’s association with blood coagulation.
Ten years later, in 1939, Vitamin K was finally isolated by E.A. Doisy from hexane extracts. 19
Nutritional Bite link 19
Vitamin K (koagulation vitamin) is an essential nutrient required for the normal biosynthesis and activation of several key proteins. There are three forms of this vitamin.
Vitamin K1, also known as phylloquinone or phytonadione, is found in green plants and is the form included in dietary supplements.
Vitamin K2, also called menaquinone, is produced by bacteria, including some found in the human intestinal tract.
Vitamin K3 or menadione, a synthetic derivative, is used as a source of vitamin K in animal feeds.
Vitamin K is an essential cofactor for enzymatic activity. It assists in the enzymatic carboxylation of glutamic acid, an amino acid found in most proteins. This carboxylation occurs after the amino acid has been incorporated into the protein chain. The added carboxyl (-COOH) groups provide a site at which calcium can bind to the protein. Through the above activity, vitamin K is involved in converting an inactive precursor of prothrombin (blood coagulation factor II) into biologically active prothrombin.
Vitamin K is similarly involved in the synthesis of at least five other proteins involved in the regulation of blood clotting. In all cases, it is thought that vitamin K assists in activating these proteins through establishment of calcium-binding sites. Other vitamin-K-dependent proteins whose function depends on calcium binding have been identified in bone, kidney, and vascular tissues. In bone, these proteins appear to be involved in bone crystal formation and bone remodeling. As a result, the potential role of vitamin K in osteoporosis has received increasing attention.
The best food sources of vitamin K are green vegetables, including spinach, broccoli, Brussels sprouts, kale, and turnip greens.
No known toxicity is associated with the administration of high doses of the natural phylloquinone form of vitamin K.
The following paragraphs provided by WHFoods
If you've read about vitamins A, B, C, D, and E, you might feel like we've missed a few vitamins as we jump over to vitamin K. But there are no vitamins F through J (at least not yet). Vitamin K is named after the German word for blood clotting (koagulation). In fact, this is probably the most common connection that people make with vitamin K—they associate this vitamin with the process of blood clotting. We'll explain more about this function of vitamin K in our "Role in Health Support" section below. However, it's important to know that vitamin K makes a variety of unique contributions to our health, and our knowledge about these contributions has been expanding in new and unexpected ways.
There are three basic types of vitamin K. Their common names are K1, K2, and K3.
The K1 form of vitamin K is found in plant foods, and 44 of our WHFoods are plant foods that serve as excellent, very good, or good sources of vitamin K! Many of our best sources of this vitamin are green vegetables (including 16 excellent sources); this makes good sense since K1 is required for green plants to conduct the process of photosynthesis. The K2 form of vitamin K is made from K1 and K3 by bacteria and other microorganisms. It can also be made in the human body through a conversion process involving K1 and K3.
In plant foods, you won't find much preformed K2, unless those plant foods have been fermented or otherwise transformed by bacteria or other microorganisms. Certain microorganisms can convert K1 into K2. A great example is Bacillus natto. This bacterium can convert K1 into K2 and it is often used in the production of fermented soy products. In fact, this practice is so common that you will sometimes find the word "natto" being used to refer to these foods. Fermented soyfoods on our WHFoods list—including tempeh and miso—can contain significant amounts of K2. (And as plant foods, they also naturally contain K1.) Most of our WHFoods animal foods also contain K2, although the amounts are relatively small and insufficient to qualify them as excellent, very good, or good sources of vitamin K.
A third type of vitamin, found preformed in food but in very small amounts, is menadione, or vitamin K3. We don't yet have good research on the health role of these small of K3 amounts in food.
Role in Health Support
As mentioned in the Description section, vitamin K is perhaps best known for its role in the blood clotting process. When people hear the term "blood clot," they might sometimes jump to the conclusion that a blood clot is bad. But there are many times when it is very important for our blood to clot. For example, blood clots are necessary to stop bleeding when our skin gets punctured.
Yet at the same time, people are correct when they say that blood clotting can cause problems. For example, if the inside of a blood vessel has become too narrow due to the buildup (over time) of plaque, this plaque can sometimes rupture and our body may form a blood clot in order to seal off the ruptured plaque. However, this blood clot might also end up stopping the flow of blood through the blood vessel since the blood vessel had become overly narrowed from the buildup of plaque.
Regardless of the specific situation, vitamin K is necessary for blood clots to form. The clotting process is very complex, requiring at least 12 proteins to function before the clotting process can be completed. Four of these protein clotting factors require vitamin K for their activity.
Vitamin K is a fascinating nutrient with respect to bone health, and unlike some of the open-ended questions related to clotting, knowledge about the role of vitamin K nourishment in bone support is fairly well-established. Individuals who are vitamin K deficient have repeatedly been shown to have a greater risk of fracture. In addition, for women who have passed through menopause and have started to experience unwanted bone loss, vitamin K has clearly been shown to help prevent future fractures.
Bone support involves different forms of vitamin K
Research has shown that our bone cells take up vitamin K in the form of K1 as well as K2, suggesting that these forms of the vitamin may play different roles in the health of our bone. In the case of K2, researchers have also become interested in two particular subtypes of K2 called MK-4 and MK-7, which appear to be uptaken by our bone cells in preference to other subtypes.
How bone support works
The bone-related benefits of vitamin K appear to depend on at least two basic mechanisms. The first of these mechanisms involves a type of bone cell called osteoclasts. Osteoclasts are bone cells in charge of bone demineralization—they help take minerals out of the bone and make them available for other body functions. While the activity of these cells is important for proper health, we do not want too many osteoclasts (or too much activity by osteoclasts) since those imbalances would mean too much demineralization of bone. Vitamin K helps our body keep this process in check. The MK-4 form of vitamin K2 (also called menatetrenone) is known to block formation of too many osteoclasts, and perhaps also to initiate their programmed cell death (a process called apoptosis).
Other Potential Health Benefits
Not suprisingly based on its role in photosynthesis and movement of electrons to generate energy, vitamin K may function as an important antioxidant nutrient especially in certain chemical forms (called "reduced" forms). In older men, vitamin K has been shown to help improve insulin resistance. In preliminary lab and animal studies, vitamin K has been investigated as a critical nutrient for protecting cells that line blood vessels, including both veins and arteries.
For a more in-depth view visit WHFoods.com
Suggested food sources with Vitamin K & relevant co-factors.
Who is Taking Care of Your Child's Cellular Nutrition
You are Right Here, Body Rox & Children's Complete Duo.