Vitamin K Update 
Summarized by Walter Sorochan

Posted November 03, 2015; updated October 20, 2021.  Disclaimer   The information presented here is for informative and educational purposes only and is not intended as curative or prescriptive advice. The statements of this web-site have not been evaluated by the United States Food and Drug Administration (FDA). Nothing stated here should be considered as medical advice for dealing with a given problem, or to diagnose / treat / prevent / cure any disease.


The belief that vitamin K is required only just for normal blood clotting is now obsolete!

Vitamin K acts as a cofactor in helping other nutrients function in the body.

Vitamin K has many forms, each with new discovered specific functions.

Ingesting calcium supplements in hopes of preventing osteoporosis without adequate vitamin K may be causing hardening of the arteries.

Many persons may be deficient in Vitamin K by not eating enough green leafy vegetables and fermented foods like Gouda cheese and Natto.

This article is about a 60-year elusive substance that dentist Weston Price, in 1945, labeled as "a new vitamin like activator"  that was originally referred to as Factor-X". Masterjohn: History of vit K 2008

Today we know it as a fat-soluble vitamin K; it is a collective term for a number of related sub-groups.

Most of us are unaware that there are three major forms of vitamin K:  Daniells: K2 booster 2012    Mercola: forgotten Vit K2

  • K1 [hytonadione/ phylloquinone/ phytonactone], commonly referred to as K; found in plants.
  • K2 [menaquinones], synthesized naturally by the bacteria in the intestines. K1 is converted to K2 in the body.
  • K3 [menadione], is a synthetic form of Vitamin K that can cause hemolytic anemia with jaundice. Not recommended!

"Although both K1 and K2 vitamins were discovered in the 1930s, two fundamental misunderstandings about these vitamins persisted for over sixty years: the medical and nutritional communities considered blood clotting to be their only role in the human body, and considered vitamins K1 and K2 to simply be different forms of the same vitamin. The first vitamin K-dependent protein [K1] relating to skeletal metabolism was not discovered until 1978. It was not until 1997, nearly twenty years later, that vitamin K was recognized as “not just for clotting anymore.”   Masterjohn: History of vit K 2008

Vitamins K1 and K2 have, since 1997, captured the attention of medical doctors for several reasons:  Daniells: K2 booster 2012  Masterjohn: History of vit K 2008   Patel: Vit K1  Kanellakis: Vit K2 & calcium regulation 2012  Ebina: Vit K2 lowers disease risk 2013 Mathew: Vit B2 foods 2014  Gast: Vit K2 reduces CVD  2009   Kanellakis: Vit K1 & K2 linked to bone health 2012   Shea: Vit K1 link to atherosclerosis 2013  Kresser: K2 missing nutrient 2008   NIH: Facts about Vit K 2015 Article by Vermeer: Vit K overview 2012 - is no longer active. Masterjohn: History of vit K 2008

Regarding vitamin K and CVD:  The 2009 Prospect Study was an independent study of 16,000 subjects who were followed for more than 10 years. Researchers calculated how much benefit you have from 10 mcg K2 per day. It turned out that each extra 10 mcg K2 in the diet gave 9% less cardiovascular events.  It is a very significant benefit. If you have 45 mcg in your supplement, it means almost 40% less risk for cardiovascular events. Gast: Vit K2 reduces CVD  2009  Mercola: Interview with Dr. Vermeer

Other Roles of Vitamin K2:

"Our understanding of the K vitamins is rapidly expanding and we are likely to discover many new roles for them as the twenty-first century progresses. The highest concentration of vitamin K2 exists in the salivary glands and the pancreas. These organs exhibit an overwhelming preference for K2 over K1 and retain high amounts of the vitamin even when animals consume a vitamin K-deficient diet. The high presence of the vitamin in both of these organs suggests a role in activating digestive enzymes, although its apparent role in the regulation of blood sugar could explain its presence in the pancreas. The testes of male rats also exhibit a high preference for and retention of vitamin K2, and human sperm possess a vitamin K-dependent protein with an unknown function.  The kidneys likewise accumulate large amounts of vitamin K2 and secrete vitamin K-dependent proteins that inhibit the formation of calcium salts.  Patients with kidney stones secrete this protein in its inactive form, which is between four and twenty times less effective than its active form at inhibiting the growth of calcium oxalate crystals, suggesting that vitamin K2 deficiency is a major cause of kidney stones." Masterjohn: History of vit K 2008

The missing piece of information in all these exciting healing/preventive researches is that we often do not know just what the research design was in the co-factor mix for vitamin K.  A poor cofactor mix would be expected to give poor or weak results and visa versa. 

What is vitamin K?

Vitamin K in general is K1.  Vitamin K1 is a yellow viscous oil, soluble in ethanol, hexane, chloroform and vegetable oils.  Vitamin K1 was named phylloquinone since it is an indirect product of photosynthesis in plant leaves where it occurs in chloroplasts and participates in the overall photosynthetic process.

Vitamin K1 is also general term K that is essential in blood clotting and if it were absent, a small cut would cause continuous bleeding in the body to the point of death. The process of blood clotting begins automatically when a tear in a blood vessel is present. When a tear in a blood vessel is present, a collection of molecules assemble rapidly to form a blood clot. Vitamin K1 helps synthesize proteins the body needs to form bone.

Although most of our vitamin K comes from plant sources, recent surveys indicate that the majority of persons are deficient in the two natural forms as K1 and K2.  Daniells: K2 booster 2012

Vitamin K1 is present in a number of dietary sources. K1 or Phylloquinone is abundant in green vegetables but poorly represented in fruits except avocado and kiwi. Grain products have also very low levels of vitamin K1. Animal products including eggs do not appear to contain appreciable amounts of vitamin K1 and less than 10 ng/g are found in fish and shellfish. High amounts are found in butter but lower amounts in cheese.

Sources of naturally occurring vitamin K-1:  NIH: Facts about Vit K 2015

Table: Selected Food Sources of Vitamin K (Phylloquinone, Except as Indicated)
Food Micrograms
(mcg) per
Natto, 3 ounces (as MK-7) 850 1,062
Collards, frozen, boiled, ½ cup 530 662
Turnip greens, frozen, boiled ½ cup 426 532
Spinach, raw, 1 cup 145 181
Kale, raw, 1 cup 113 141
Broccoli, chopped, boiled, ½ cup 110 138
Soybeans, roasted, ½ cup 43 54
Carrot juice, ¾ cup 28 34
Soybean oil, 1 tablespoon 25 31
Edamame, frozen, prepared, ½ cup 21 26
Pumpkin, canned, ½ cup 20 25
Pomegranate juice, ¾ cup 19 24
Okra, raw, ½ cup 16 20
Salad dressing, Caesar, 1 tablespoon 15 19
Pine nuts, dried, 1 ounce 15 19
Blueberries, raw, ½ cup 14 18
Iceberg lettuce, raw, 1 cup 14 18
Chicken, breast, rotisserie, 3 ounces (as MK-4) 13 17
Grapes, ½ cup 11 14
Vegetable juice cocktail, ¾ cup 10 13
Canola oil, 1 tablespoon 10 13
Cashews, dry roasted, 1 ounce 10 13
Carrots, raw, 1 medium 8 10
Olive oil, 1 tablespoon 8 10
Ground beef, broiled, 3 ounces (as MK-4) 6 8
Figs, dried, ¼ cup 6 8
Chicken liver, braised, 3 ounces (as MK-4) 6 8
Ham, roasted or pan-broiled, 3 ounces (as MK-4) 4 5
Cheddar cheese, 1½ ounces (as MK-4) 4 5
Mixed nuts, dry roasted, 1 ounce 4 5
Egg, hard boiled, 1 large (as MK-4) 4 5
Mozzarella cheese, 1½ ounces (as MK-4) 2 3
Milk, 2%, 1 cup (as MK-4) 1 1
Salmon, sockeye, cooked, 3 ounces (as MK-4) 0.3 0
Shrimp, cooked, 3 ounces (as MK-4) 0.3 0

DV = Daily Value. DVs were developed by the U.S. Food and Drug Administration (FDA) to help consumers compare the nutrient contents of products within the context of a total diet. The DV for vitamin K is 80 mcg for adults and children age 4 and older. However, the FDA does not require food labels to list vitamin K content unless a food has been fortified with this nutrient. Foods providing 20% or more of the DV are considered to be high sources of a nutrient.

The U.S. Department of Agriculture's (USDA's) Nutrient Databaseexternal link disclaimer website [16] lists the nutrient content of many foods and provides comprehensive lists of foods containing vitamin K (phylloquinone) arranged by nutrient content and by food name, and of foods containing vitamin K (MK-4) arranged by nutrient content and food name.

Vitamin K is found in most green plants including, vegetables, young wheat grass, alfalfa and spirulina. As of 2013, researchers did not have adequate information about the different forms of vitamin K in foods.  Lack of such detailed information makes it difficult to make good dietary recommendations.

Vitamin K1 is sensitive to sunlight and is destroyed after one hour.

What is Vitamin K2?

So, what is natto?

Natto is typically fermented from soybeans or chickpeas using a healthy bacteria called bacillus subtilus that may also serve as a probiotic.

Fermented foods, like natto, typically have the highest concentration of vitamin K in the human diet. Levels of vitamin K found in natto (K2) have been shown to far exceed those amounts found in dark green vegetables (K1).

Vitamin K2 concentration after the consumption of natto has been shown to be about 10 times higher than that of vitamin K1 after eating spinach.

The best sources of vitamin K2 are fermented foods and grass-fed animal fats. These foods contain a wide array of nutrients , like vitamin A, B-complex, D, C and minerals that may act synergistically as co-factors with vitamin K2.

Vitamin K2 becomes a major nutrient player due to its ability to boost the metabolic formation of bone. Vitamin K2 is an essential helper to calcium, vitamins D and C and other nutrients in making bones stronger, preventing osteoporosis and also participating in many other body healing and preventing roles.  Daniells: K2 booster 2012   Kanellakis: Vit K2 & calcium regulation 2012 

Many bacteria, such as Escherichia coli found in the large intestine, can synthesize vitamin K2 (menaquinone-7 or MK-7, up to MK-11), but not vitamin K1 (phylloquinone).  Wiki: vit K

Vitamin K2 includes several forms referred to as menaquinones. For example, MK-4 is normally synthesized from vitamin K, in certain animal tissues like arterial walls, pancreas and testes.  MK-4 is also found in meats, and MK-7, MK-8, and MK-9 found in fermented food products like cheese and natto [made of fermented soybeans and Bacillus subtilis, which provides an unusually rich source of K2 ]  It is not known whether B. Subtilis will produce K2 with other legumes, like chickpeas, beans and lentils. Wiki: vit K

MK-4 has been shown to decrease the incidence of fractures by 87%.  MK-4  [ 45 mg daily ] has been approved by the Ministry of Japan since 1995 for the prevention and treatment of osteoporosis but not in the USA.  Wiki: vit K

Discussion is ongoing as to what extent K2 produced by intestinal bacteria contributes to daily vitamin K2 needs.  Overlooked in the discussion is that bacteria in the colon need to be cultivated with special foods. Intestinal bacterial may not be able to supply enough K2 to supplement all tissues and cells needing K2.  Hence, one needs to eat foods that feed vitamin K2 bacteria! 

Vitamin K2 is preferred by the extra-hepatic tissues (bone, cartilage, vasculature) and this may be produced as MK-4 by the animal from K1, or may be of bacterial origin [MK-7, MK-9, and other MK numbers].

Vitamin K2 Dietary intake sources

There are different varieties of K2, depending on the food. There’s MK-1 from plants, and MK-4 from animal products like eggs, chicken breast, offal, or roughly 37 micrograms a day suggested by the Rotterdam Heart Study etc.  Another example is Gouda cheese that is high in K2 [ approximately 20 mcg per ounce ].   It is probable that the longer cheese is aged, the lower the the vitamin K2 content. In fermentation of milk by mesophilic bacteria, the vitamin K2 is synthesized from lactose. When lactose is largely depleted, probably within a week, production of vitamin K2 stops and thereafter vitamin K2 content declines slowly.  Mathew: Vit B2 foods 2014

Vitamin D helps you absorb calcium while vitamin K2 tells your body where to put it — into the bones where it belongs, not the delicate inner lining of the blood vessels and arteries. Calcified arteries lead to heart attacks. So it looks like eggs, cheese and butter [ from cows fed on grass grown fields ] may be part of a heart healthy diet, contrary to popular dogma.

Chemistry of vitamin K:

Chemical structure of different vitamin K forms

Vitamin K is a rather small molecule, only it is not soluble in water. So you need fat in the meal to absorb it. Capsules are always in certain oils [sunflower seed oil] that can easily dissolve your Vitamin K. You also need in the intestines a certain bile excretion. Of course, when you eat or ingest a meal, it is a little bit fatty. There, you have sufficient bile production. In the intestines, you have myoceles in which this Vitamin K is incorporated pretty easily. Then it is just transported through the wall of the intestines into the lymph and into the blood stream, until it reaches the liver. Mercola: Interview with Dr. Vermeer

Vitamin K chemical structure varies.  Vitamin K not a single compound, but a group name for a family of related structures that all share a methylated naphthoquinone ring system substituted with a variable aliphatic side chain. [ refer to the illustration on the right ] In phylloquinone (vitamin K1) the side chain is composed of four isoprenoid residues, the last three of which are saturated. Menaquinones (vitamin K2) form a sub-family in which the length of the side chain may range from 1 to 13 isoprene residues, all of which are unsaturated. The various menaquinones are generally denoted as MK-n, where n represents the number of isoprene residues in the aliphatic side chain. Important menaquinones are the short chain MK-4 and the long chain menaquinones MK-7, MK-8, MK-9, and MK-10 that all occur in the human diet, whereas small amounts of MK-6 have also been found in various foods.  Article by Vermeer: Vit K overview 2012 - is no longer active.

Another explanation about how vitamin K works is provided by Dr. Vermeer, the world's expert on vitamin K:   Article by Vermeer: Vit K overview 2012 - is no longer active.

"Vitamin K received its name from the fact that it is required for normal blood coagulation, and during about half a century it was believed that hemostasis was the only metabolic process in which vitamin K is involved. This view is obsolete now. Since the identification of Gla [ Gla is an amino acid that is part of certain proteins that control calcium.] as the result of vitamin K action, it became possible to search for vitamin K-dependent proteins on the basis of their amino acid structure: each protein in which gammacarboxyglutamate, generally referred to as Gla. is found contains the fingerprint of vitamin K action during its biosynthesis. In this way a wide variety of proteins were found ranging from osteocalcin (the most abundant non-collagenous protein in bone), to matrix Gla-protein (MGP, the potent calcification inhibitor in our arteries), and the growth-arrest sequence-6 protein (Gas6, a protein involved in cell growth regulation). Whereas the proteins involved in blood coagulation invariably are synthesized in the liver, the newly discovered Gla-proteins have key functions in other metabolic processes and are synthesized in a wide variety of tissues. An overview of the various Gla-proteins and their functions (as far as they are known) is given in Table 1 below."

Table 1. Classification of the 17 Gla-proteins according to their function
Function Name of protein
Haemostasis (procoagulant activity) Prothrombin, factors VII, IX, and X
Haemostasis (anticoagulant activity) Proteins C, S, and Z
Artery calcification inhibition Matrix Gla-Protein (MGP)
Bone metabolism Osteocalcin
Cell growth regulation Growth-arrest sequence 6 protein (Gas6)
Functions unknown Gla-rich protein (GRP)
Periostin-like factor
Four transmembrane Gla-proteins

Dr. Vermeer's classification of vitamin K, on the basis of proteins, identifies how vitamin K functions in the body.  Vitamins K 1 and K2 are involved in numerous metabolic processes and this article will simplify these at the risk of inadvertently omitting some key details and being at times redundant.

Natural Vitamin K is required for two bone matrix proteins: osteocalcin and matrix-Gla [gamma carboxyglutamic acid]. Gla is an amino acid that is part of certain proteins that control calcium. Vitamin K is shown to be beneficial in bone health because it helps to produce the natural protein osteocalcin [ noncollagemous protein found in bone and dentin ]. Basically, osteocalcin acts as the structural framework holding calcium in place in your bones and teeth.  And vitamin K is critical for producing osteocalcin protein.  This is important because osteocalcin cannot perform its job until vitamin K converts it to an active bone-building form.  Without this vitamin K key action, you simply wouldn't have the strong bones you do.

But vitamin K2 plays other important roles such inhibiting osteoclasts and help maintain your bones [ the cells that generate or lay down bone and produce a specific protein known as Osteocalcin. ]  The key action – vitamin K is the "key" that unlocks the door from your bloodstream to let calcium flow into your bones and bone marrow osteoblasts.  Such a key also regulates whether calcium deposits occur in the inner lining of arteries.  Masterjohn: History of vit K 2008

Calcium needs these K-proteins to crystallize and strengthen bone tissue. Thus, Vitamin K is required for proper bone formation and blood clotting. In both cases, Vitamin K accomplishes the job by assisting the body in transporting calcium. 

Vitamin K has another critical function.  Like osteocalcin, however, MGP [ refer to table above ] can only fulfill its function once it has been activated by vitamin K.  MGP has the task of protecting the arteries from calcification [hardening of the arteries].   Masterjohn: History of vit K 2008

Absorption of K1 is from the gut (duodenum and jejunum) via the lymphatic system. Thus, conditions that impair the fat absorption will also affect the absorption of Vitamin K. Antibiotics destroy the beneficial bacteria in the intestine needed for Vitamin K synthesis.

Phytonadione (K1) is an analogue of Vitamin K, but it has the quickest onset of action, the most prolonged duration, and is the most potent of all the Vitamin K forms. K1 is safer than menadione (K3) to use on newborns.

This, we need to juggle a ratio balance between vitamin K and all the other essential vitamins and minerals, and especially calcium. 

Co-factor dependent: 

Vitamin K2 will never do the work alone. You also need other health helpers. One of them is Vitamin D. The two collaborate; there is a synergistic effect of Vitamin D and Vitamin K.  Vitamin K acts as a cofactor in helping other nutrients function in the body. Mercola: Interview with Dr. Vermeer

The following quote by Masterjohn illustrates this: "Vitamin K is the substance that makes the vitamin A- and vitamin D-dependent proteins come to life. While vitamins A and D act as signaling molecules, telling cells to make certain proteins, vitamin K activates these proteins by conferring upon them the physical ability to bind calcium. In some cases these proteins directly coordinate the movement or organization of calcium themselves; in other cases the calcium acts as a glue to hold the protein in a certain shape. In all such cases, the proteins are only functional once they have been activated by vitamin K.  Osteocalcin, for example, is a protein responsible for organizing the deposition of calcium and phosphorus salts in bones and teeth. Cells only produce this protein in the presence of both vitamins A and D; it will only accumulate in the extracellular matrix and facilitate the deposition of calcium salts, however, once it has been activated by vitamin K, vitamins A and D regulate the expression of matrix Gla protein [MGP] [ a protein regulating mineral deposit and bone organization ] which is responsible for mineralizing bones."   Masterjohn: History of vit K 2008

Testing for Vitamin K:

Lack of an inexpensive and easy to use test makes it difficult for people to find out if they a deficient in vitamin K!

The only clinically significant indicator of vitamin K status  in the USA is prothrombin time [ the time it takes for blood to clot ], and ordinary changes in vitamin K intakes have rarely been shown to alter prothrombin time. NIH: Facts about Vit K 2015

Scientists in Europe are working on better and less expensive vitamin K tests.  These are future prospects for accurate, inexpensive and easy to use tests. The hope is to be able to  screen the whole population for risk of artery calcification! Another option of this test that’s a little bit different application is to more or less quantify the amount of calcium already present in the arteries. So you can do a pre-selection of those who need very expensive techniques like electron beam computed tomography. You can just take a drop of blood and place it on a piece of sensitive paper. The test itself can be made with just like a microtiter plate essay or an automated clinical lab assay. Such a test should not be too expensive, between 20 and 50 dollars or so. This could be a home test, so that people can just go to the drugstore and buy it.  Dr. Vermeer expects such tests within the next three years.  Mercola: Interview with Dr. Vermeer

Vitamin K measurements in blood plasma can be done quite accurately, but the question is whether it’s helpful because it mainly reflects what you have eaten yesterday. You can also measure the activity of the Vitamin K-dependent proteins.   NIH: Facts about Vit K 2015

Currently, there are several tests being refined and patented:  If you want to know your Vitamin K status in the vasculature, then you have to measure the circulating level of inactive MGP. Dr. Vermeer has a patent on the method to do that. This is a very accurate and good method that protects the risk of your arteries getting calcified.


There is confusion as to whether persons in the USA and Canada have vitamin K deficiencies. National Institutes of Health points out that such assessments in the USA population are not accurate.  NIH: Facts about Vit K 2015  Numerous researchers have estimated from their studies that millions of persons may be deficient in vitamin K1 and/or k2.   As mentioned earlier, such deficiencies are linked to osteoporosis, fragile bones,  cardiovascular disorders, high blood pressure, diabetes, kidney stones and other disorders.  Vitamin K deficiencies appear to be prevalent in the those over age 60 who suffer from visible osterporosis. 

Vitamin K deficiency can occur when the body can't properly absorb vitamin K from the intestinal tract and/or when the diet is deficient in green leafy vegetables. This problem may also be caused by certain diseases such as cystic fibrosis, celiac disease, and Crohn's disease, as well as long-term use of antibiotics or blood-thinning medications, or treatment with hemodialysis. Signs and symptoms of vitamin K deficiency include excessive bleeding and bruising. Article by Wong: Vit K info 2015 is no longer active.

Although the exact dosing is yet to be determined, Dr. Cees Vermeer, one of the world’s top researchers in the field of vitamin K, recommends 150 mcg daily for healthy adults. Dr. Vermeer points out that present recommendations for dietary intake are based on the daily dose required to prevent bleeding. Accumulating scientific data suggests that new, higher recommendations for vitamin K intake should be formulated. Article by Vermeer: Vit K overview 2012 - is no longer active.

The RDA for Vitamin K for adult females 19 and older is 90 micrograms of the vitamin per day, and 120 micrograms per day for men age 19 and older. NIH: Facts about Vit K 2015

Fortunately, you don’t need to worry about overdosing on K2—people have been given a thousand-fold “overdose” over the course of three years, showing no adverse reactions [i.e., no increased clotting tendencies].

Precautions: Vitamin K should not be taken without prior medical consultation if pregnancy is suspected or if one is breast-feeding. Antibiotics and certain steroidal preparations may deplete or interfere with Vitamin K. Blood-thinning medications like arfarin and dicumarol will adversely interact with Vitamin K. Vitamin K inhibitors include: x-rays, radiation, aspirin, mineral oil, and laxatives. High amounts of Vitamins A and E can actually block Vitamin K, necessitating supplementation to compensate.

Deficiency symptoms of Vitamin K:

Symptoms may include decreased clotting, nosebleeds, increased blood pressure, hemorrhages, and diarrhea.

Vitamin K supplements:

The best vitamin K2 supplement is made from Natto.  Jarrow Formulas and Source Naturals both offer cost-effective MK-7 supplements. Source Naturals’ product is less expensive, but Jarrow’s contains fewer additives and certifies that the soy used to make the product is not genetically modified. Masterjohn: History of vit K 2008  Although there may be justification for supplementation, this author does not endorse any of these supplements at this time.

As of 2015, there is no way to test for vitamin K2 deficiency. But by assessing your diet and lifestyle as mentioned above you can get an idea of whether or not you may be lacking in this critical nutrient. The next best thing to dietary vitamin K2 is a vitamin K2 supplement. MK-7 is the form you’ll want to look for in supplements, because in a supplement form the MK-4 products are actually synthetic. They are not derived from natural food products containing MK-4. The MK-7– long-chain, natural bacterial-derived vitamin K2– is from a fermentation process, which offers a number of health advantages: It stays in your body longer It has a longer half-life, which means you can just take it once a day in very convenient dosing.  Finally, remember to always take your vitamin K supplement with fat since it is fat-soluble and won’t be absorbed without it. Mercola: Interview with Dr. Vermeer


There is no evidence of toxicity associated with the intake of either K1 or K2. 

Vitamin K is unique because it has multiple effects in your body, but doesn’t demonstrate any known toxicity. With research focused on potential effects on your skeletal system, brain, liver, and pancreas, vitamin K is one of the most promising nutrients of our time.

Vitamin K3 is a a synthetic variant of the vitamin and is not recommended for human consumption. It can cause hemolytic anemia [due to dying red blood cells], causing jaundice, liver damage and severe neurological damage. Avoid ingesting supplement vitamin K3!  Mercola: Interview with Dr. Vermeer

 Alert:  Lack of co-factor balance in vitamin K nutrients can cause health problems.  Medical science lacks good co-factor information at this time, so you need to consult an informed pharmacist and health specialist when taking nutritional supplements. Here are a few examples: 

Supplementing with excess amounts of calcium, without simultaneously getting adequate amounts of vitamin K-2, or menaquinone, in your nutrition is harmful.  The result can be atherosclerosis or hardening of the arteries. Mercola: Interview with Dr. Vermeer

Another possible imbalance of co-factors, like high amounts of Vitamins A, D, C and E can actually block Vitamin K, necessitating supplementation to compensate. 

Vitamin K supplements without a balance of protein [ amino acids ] calcium, sulfur, and vitamins A, D, and C may cause numerous health problems.


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