Written by Slawomir Gromadzki, MPH

Vitamin K2 natto article

Vitamin K is a group of fat-soluble vitamins that the human body requires for synthesis of certain proteins needed for blood coagulation. Without vitamin K, blood coagulation is seriously impaired, and uncontrolled bleeding occurs.

Vitamin K was accidentally discovered in the 1920s after restricted diets in animals led to excessive bleeding. Since the discovery of vitamin K was first reported in a German journal, the “K” is derived from the German word “coagulation,” which means the ability to clot blood.


Unlike the other fat-soluble nutrients (vitamins A, D and E), vitamin K is not stored in the body, so it must be consumed daily.

According to Dr. Cees Vermeer a renowned vitamin K expert and researcher, majority of people are deficient in vitamin K.

Studies show that even if we have sufficient vitamin intake to prevent bleeding disorders, we may have insufficient Vitamin K intake to prevent degenerative diseases including atherosclerosis (arterial calcification), osteoporosis and cancer.

Even a diet that is rich in leafy greens supplies only half of the required vitamin K amount to continue the calcium regulating activities in the body.


– Taking antibiotics can reduce vitamin K production in the gut by nearly 74%.

– Regular consumption of processed or fast foods that contain hydrogenated oils, increase risk of vitamin K deficiency. Canola and Soy may contain some vitamin K but their hydrogenating processing makes them useless.

– Deficiency of vitamin K is more likely in people with digestive problems such as irritable bowel disease or celiac disease, as they increase the likelihood of fat malabsorption.

– Absorption of vitamin K, like that of other fat-soluble nutrients (A, D and E), depends on healthy liver, gallbladder and digestive function.

– Older adults require more to get the desired effects.

– Warfarin leads to vitamin K deficiency.


There are 3 basic types of vitamin K (K1, K2 & K3):

  1. Vitamin K1 (phylloquinone, phytonadione, phytomenadione), which is found in plants, especially green leafy vegetables like spinach, kale & collard greens. It is also used as a dietary supplement.
  2. Vitamin K2 (menaquinone) exsists in the form of MK4, MK7, MK8 & MK9:

MK-4 is present in animal foods (meat, eggs, cheese, etc.). However, I don’t recommend animal foods as good vitamin K sources because they greatly increase risk of developing cancer and other serious diseases. MK4 has a limited life in our body.

– There is also another type of vitamin K2, called MK-7, which comes from fermented natto and is regarded as the best and most bioavailable type of vitamin K. Sauerkraut and kimchi can also contain vitamin K2, but typically in significantly lower amounts around 10-15 mcg per cup.

– MK8 and MK9 which come primarily from dairy products (especially cheese) are far less effective than MK4 and especially MK7.

  1. Vitamin K3 (menadione) – synthetic variant. Because synthetic form can be toxic by interfering with the function of glutathione, it is no longer used to treat vitamin K deficiency.

Plants synthesize vitamin K1 and animals eat plants with vitamin K1 and convert it to MK4 form of vitamin K2. Therefore, animal foods, such as dairy and meats, contain MK4 but at levels much smaller than those studied and shown to be helpful in humans. For this reason consuming animal foods that contain vitamin K2 (MK4) doesn’t seem to solve the problem all the more the same foods greatly increase risk of many dangerous diseases. It is therefore much safer and reasonable to take supplements with K2 MK4 combined with MK7.

In contrast, MK7 is produced by bacteria. Humans nor animal cannot make MK7. It can be consumed with foods such as natto or in the form of supplements.


We need Vitamin K1 for blood clotting and our liver preferentially uses Vitamin K1 to activate clotting factors. Its deficiency in infants and children has been linked to serious bleeding disorders.

Our need for vitamin K is based on the amount necessary to maintain a normal balance between blood clotting and thinning. Blood shouldn’t be excessively “thinned” and prone to abnormal bleeding, nor excessively “thick”. Unfortunately, research provides evidence that unlike Vitamin K2 Vitamin K1 doesn’t work on our bones and it does not promote heart health.

Vitamin K1 in 1 cup of the cooked vegetable:

Kale: 1,000 mcg

Collard greens: 1,000 mcg

Spinach: 900 mcg

Turnip greens: 500 mcg

Broccoli: 200 mcg

Brussels sprouts: 200 mcg


Our body can convert Vitamin K1 into K2 however studies show that the amount of K2 produced by this process alone is insufficient.

Fermented foods such as natto and raw sauerkraut are considered the better food sources of K2.

Our intestinal bacteria produce some Vitamin K2 but this is of no benefit to our body as it can’t be absorbed from the gut and is removed with the stool.

The vitamin K2 content in 3.5 ounces (100 grams):

Natto: 1,000 mcg

Hard cheeses: 70 mcg

Chicken (leg/thigh): 60 mcg

Soft cheeses: 50 mcg

Egg yolk: 30 mcg

Sauerkraut & Kimchi: 10-15mcg



Our body needs vitamin K to help wounds heal, by making sure our blood clots properly. It seems that both K1 and K2 increase blood clotting.

One study showed that a single serving of natto rich in vitamin K2 altered measures of blood clotting for up to four days and this effect stronger than from foods high in vitamin K1 (>).


Vitamin K improves absorption of vitamin D and prevents calcification caused by overdosing vitamin D.

To maximize the benefits of vitamin D supplementation while also minimizing the potential risk of toxicity vitamin D should be taken with K2.

Vitamin K activates the MGP, a protein that helps direct calcium to the right places (bones) and lead calcium away from the undesirable areas (pineal gland, kidneys and arteries) eliminating risk of hypercalcaemia and calcification of these organs.

Apart from Vitamin K also Magnesium plays crucial role in proper conversion and absorption of Vitamin D. As a matter of fact, taking even highest doses of supplemental Vitamin D gives no benefits in people who are deficient in Magnesium.


Together with vitamin D vitamin K make sure that the calcium in your body is stored in bones and used to make them strong and healthy. Without these two vitamins calcium cannot be stored in bones! For this reason calcium supplement should always be taken with vitamin D3 and K2 MK7!

Take vitamins D3 and K2 to ensure proper assimilation of the calcium into the bones to maintain bone strength so it doesn’t end up in places that will cause pain and inflammation.

Vitamin K is required for the production (in osteoblasts) and proper function of enzyme osteocalcin required for proper bone-forming process. Vitamin K2 has been found to be far more effective in this process than Vitamin K1.

Inadequate K2 inhibits osteocalcin production and reduces calcium flow into bone tissue.  This leads to reduced bone mass.

Japanese trials have demonstrated that vitamin K2 can reverse bone loss and increases bone mass in people with Osteoporosis. The evidence shows that Vitamin K2 supplementation produces a 60% reduction in vertebral fractures and an 80% reduction in hip and other non-vertebral fractures.

A two-year study found that 45 mg/day of vitamin K2 reduced the incidence of vertebral (spine) fractures by 52% in 120 patients with osteoporosis, compared with patients who did not receive this nutrient.

Numerous clinical trials using 45 mg per day of MK4 indicate that this mega dose of MK4 taken daily may decrease fractures more than 80%. For instance, a 2006 study concluded that 45 mg of MK4 can decrease vertebral fractures by approximately 60%, hip fracture by 70%, and all non-vertebral fractures (ribs & wrist) by 80%.

Postmenopausal women taking 1,500 mg of calcium along with 45 mg of vitamin K2 daily experienced an increase in bone mineral density and a 55.9% reduction in inactive osteocalcin levels, a marker which is elevated in osteoporotic patients and related to an increased hip fracture risk.

Another study revealed that when 180 mcg of vitamin K2 daily was used for 3 years, it produced significant improvements in bone mineral density and increased bone strength.


Never take calcium supplements without vitamin K2 MK7, D3 and good magnesium, because if you are deficient in these nutrients (and almost all people today are), calcium you get from supplements, hard water or milk and dairy, instead of strengthening your bones will be deposited in pineal gland (leading to its calcification), kidneys (causing kidney stones), joints (osteoarthritis), veins (varicose veins and haemorrhoids), colon (constipation), and arteries (causing their hardening and leading to heart attacks and strokes).


Studies gave strong evidence that higher calcium intake through supplements can significantly increase heart attacks because calcium builds up in the blood vessels causing their hardening and contributing to thickening and blockage. A 139% increase in risk was noted in one study (>).

One of the most important activities of vitamin K is to protect the entire cardiovascular system by preventing calcification of the arteries. In one study Vitamin K2 reduced blood vessel calcification whereas vitamin K1 did not.

In our blood, Vitamin K2 participates in carboxylation of Matrix Gla Protein (MGP), the most potent inhibitor of arterial calcification known. In this way Vitamin K2 prevents vascular damage by lowering the risk of calcification (hardening) of arteries. This effect is more beneficial when Vitamin K2 is combined with Vitamin D3 and Magnesium. Vitamin K and vitamin D work to increase a substance called Matrix GLA protein (MGP).  This protein protects the blood vessels from calcification by congregating around the elastic fibres of the arterial lining and guarding against calcium crystal deposition. Some experts maintain that MGP is the most powerful inhibitor of soft tissue calcification currently known.

Animal studies have shown that vitamin K2 not only prevents hardening of blood vessels but actually has the potential to reverse arterial calcification by activating MGP. A trial followed 16,000 people for 10 years found that each additional 10 mcg of K2 in the diet reduces cardiac events by 9 percent!

The 2004 Rotterdam Study revealed that people who consume 45 mcg of Vitamin K2 per day live seven years longer than people getting only 12 mcg per day. It also demonstrated that they had a 50% lower risk of death from heart disease than people with the lowest rates of K2.


A long-term study published in 2016 evaluated the health status of 257 men and women aged 55-65 who at that time were free from hypertension and cardiovascular disease. Most of them were deficient in vitamin D and K as they had increased uncarboxylated matrix Gla-protein levels (MGP). Since the MGP becomes carboxylated from vitamin K their uncarboxylated MGP levels indicated vitamin K deficiency.

After six years approximately half of the participants developed hypertension. The researchers determined that both low vitamin D and high uncarboxylated MGP levels were associated with an increased risk for developing hypertension.

The risk of developing hypertension was much higher with both low vitamin D and high uncarboxylated MGP levels compared to the risk with only low vitamin D levels or merely high uncarboxylated MGP levels.


Not only Calcium but also Vitamin D supplements should be always taken with Vitamin K2 (50 mcg of K2 MK7 per every 1000 IU of Vitamin D), especially when high doses of vitamin D are taken for a long time. Taking vitamin K2 will prevent Vitamin D from depositing calcium in joints, calcification of blood vessels or kidney stones caused by long-term overdosing of vitamin D. I myself always recommend vitamin D3 supplementation due to its widespread deficiency but it should always be accompanied by proper intake of Vitamin K2 and Magnesium (without enough Magnesium in the body Vitamin D cant be converted and is useless).

The main consequence of vitamin D toxicity is a build-up of calcium in the blood (hypercalcaemia), which may cause weakness, nausea and vomiting, frequent urination, etc. These symptoms might progress to arterial calcification, bone pain and the formation of calcium stones in kidneys.

Taking over 50,000 international units (IU) a day of vitamin D for longer time such as several months may lead to toxicity. Such mega doses can be taken but only for shorter periods of time (1 to 3 months) followed by the reduction of the dosage to 5-10,000 IU per day and always with 100-200mcg K2 and 2 times a day 400-800mg of Magnesium (such as citrate).

Treatment of Vitamin D toxicity includes stopping vitamin D intake and restricting dietary calcium until recovery.


Fit and trim at age 67, Walter had no reason to believe that he had any hidden health conditions. However, when he decided to undergo a computed tomography heart scan his heart scan score was as high as 3,367 which indicated a dangerous content of calcified atherosclerotic plaque in his coronary arteries, pointing to a high risk of heart attack.

At the same time, another test showed that he had bone density of someone 20 years older, revealing an advanced state of osteoporosis.

His arterial calcification and osteoporosis were likely connected through the common mechanism of inadequate levels of vitamin K.

Lack of this vitamin caused calcium to be deposited in his arteries instead of bones, leading at the same time to their decalcification.


It seems that calcium build-up in the veins may be a cause of varicose veins and vitamin K2 supplementation prevents it.

New research shows vitamin K deficiency leads to accumulation of calcium in muscle cells found in the walls of the veins causing varicose veins (Toumanizntz, Boularan, Schurgers, et al. 2007).


Vitamin K protects against cancer by suppressing the genes that make cells abnormal (cancerous) and expressing the genes that make cells healthy.

The European Prospective Investigation into Cancer study, discovered that high intake of Vitamin K2 (as opposed to K1) lowers risk of dying from cancer by thirty percent.

A German study showed that men taking the highest amounts of K2 have about 50 percent less prostate cancer.

A National Cancer Institute funded study concluded that vitamin K2 could help reduce the risk for non-Hodgkin lymphoma. It discovered that people with the highest intake of vitamin K2 had a 45 percent lower risk for this type of cancer.


Vitamin K is known to support cognitive brain functions and prevents dementia, Alzheimer’s disease and calcification of brain’s pineal gland.


A dreaded adverse effect of chemotherapy treatment is bone marrow failure, known as myelodysplastic syndrome in which the patient’s bone marrow is unable to make platelets and blood cells. Without weekly platelet and red cell transfusions, the patient would not survive. However, Dr Takami reported in 1999 successful therapy of myelodysplastic syndrome using extremely high dosage of 45 mg (not mcg) a day of Vitamin K2 supplementation. That seems a lot as recommended daily intake for adults is about 100 mcg and available on the market supplements contain between 50 and 500 mcg per dose.


Newer research shows the importance of vitamin K in carbohydrates and energy metabolism. In addition to assisting in producing pancreatic cells, vitamin K also increases production of an insulin-sensitizing hormone called adiponectin, which is produced by fat cells and improves insulin sensitivity and glucose tolerance. It means that Vitamin K helps cells in our body remain very sensitive to insulin and lover blood sugar when its higher than normal, protecting against diabetes and preventing accumulation of fat.


Vitamin K plays an important role in protecting skin elasticity. Currant research revealed that people who cannot metabolize vitamin K develop premature skin wrinkling. (Gheduzzi, Boraldi, et al. 2007).

Vitamin K2 intake reduces wrinkles because it helps prevent calcium from depositing in elastin fibres. Since vitamin K protects elastin (protein that gives the skin the ability to spring back) from excess calcium, it is free from calcification and able to keep the skin smooth and wrinkle free.


Vitamin K and D also play very important role in joint health.  When body tissues are damaged due to oxidative stress the body responds by triggering inflammation which results in calcium accumulation in the damaged tissues which builds up a plaque in blood vessels and also creates degenerative bone spurs in joints. Vitamin K2 MK7 prevents calcium from being deposited in joints.


According to a 2015 study results “Vitamin K2 in the form of menaquinone-4 (MK-4) has been shown to reduce the proliferation of rheumatoid synovial cells. Recently, it was found that 45 mg per day of MK-4 reduced clinical and biochemical markers of disease activity. For these reasons, MK-4 has been recommended as a new agent for the treatment of RA either alone or in combination with standard RA therapy. MK-7 is a form of vitamin K2 that has greater bioavailability than MK-4 after oral administration, but the therapeutic utility of MK-7 in RA had not been investigated previously. The present study revealed that administration of MK-7 (100 µg/d) to RA patients for 3 months decreased levels of CRP, ESR, DAS28-ESR, and MMP-3, suggesting that this form of vitamin K2 is also effective in the treatment of RA.” (>)


Vitamin K promotes sexual health by helping us optimize sex hormones. Vitamin K2 MK4 is used for steroid production in the male testis. Studies in rats have showed that 75 mg/kg of MK4 enhanced testosterone levels compared to the control.

Vitamin K increases testosterone and fertility in males, while lowers the excess of the same male sex hormone (testosterone) in women. In women high testosterone is triggered by high insulin levels (insulin resistance) which leads to polycystic ovarian syndrome (PCOS). Polycystic ovary syndrome is also characterized by an overproduction of DHEA sulfate (DHEAS).

Vitamin K2 supplementation helps women to recover from PCOS. K2 will give even better results combined with D3, magnesium, chromium, karela, alfalfa and alpha lipoic acid. Read more about PCOS >

One randomized control trial showed that Vitamin D, K and calcium (citrate not carbonate!) co-supplementation for two months among Vitamin D-deficient women with PCOS managed to lower DHEAS levels and testosterone levels.


Vitamin K helps improve exercise performance by enhancing our ability to utilize energy during bouts of physical activity.


Vitamin K can be available as a supplement, either as K1 or K2.

Vitamin K2 can be either MK-4, MK-7, MK8 or MK9.

– MK4 has a short life in our body but it is highly bioavailable. Naturally MK4 is found in eggs and meat but in concentrations way too low to give the same results as in studies where high doses were used. In addition animal foods shouldn’t be recommended as a source as they are the key nutritional cause of numerous dangerous diseases including cancer. For this reason MK4 should be used only in the form of nutritional supplements and combined with MK7. MK4 used in dietary supplements is a plant-derived, natural product created and purified in a manufacturing facility.

Although the life of MK4 in our body is much shorter than that of MK7 yet on the other hand MK4 is taken up by our tissues very rapidly after we ingest it. While it hasn’t been studied as extensively as MK7, and it may be less effective than MK7 at reaching liver and bones but it may be more effective at reaching other body tissues and protecting them from calcium deposits, cancer and supporting sex hormone production.

– MK7 (Menaquinone-7) seems to be the best nutritional source and very good supplemental form of vitamin K as it is much more bioavailable and bio-efficient than MK1 and in our body it is converted to MK4. MK7 is extracted from Japanese fermented soy product called natto which is the best natural food source of this form of vitamin K2. Unfortunately, since most people are not used to consume natto and can’t tolerate its smell and taste supplementation is the way to obtain this form of vitamin K2.

Vitamin K2 as MK7 requires a minimum dose of 45 µg/day to activate osteocalcin carboxylation in healthy subjects; while MK4 needs a minimum dose of 1500 μg/day.

MK4 is cleared from the body in only six to eight hours while MK7 remains active in the body for several days being able to accumulate to provide a constant reserve of bioavailable K2.

MK4 works only in in the form of high strength supplements. The amount of this form present in animal food does not improve serum vitamin K levels. MK-7, however increases serum levels even if ingested with food such as natto.

– MK8 and MK9 which come primarily from dairy products (especially cheese) are far less effective than MK4 and MK7.

So, to make it clear, plants synthesize vitamin K1, animals eat those plants with vitamin K1 and convert it to vitamin K2 MK4. Therefore, animal foods, such as dairy and meats, contain MK4 but at levels much smaller than those studied and shown to be helpful in humans. For this reason consuming animal foods that contain vitamin K2 (MK4) doesn’t seem to solve the problem all the more the same foods greatly increase risk of many dangerous diseases.

In contrast, MK7 is produced by bacteria. Humans nor animals cannot make MK7. It can be consumed with foods such as natto or in the form of supplements. In our body MK7 is converted to MK4.

Taking into consideration the above mentioned facts it seems reasonable to aim at taking a good quality supplements which contain MK7 (50-1,000 mcg) combined with MK4 (1,500-50,000 mcg) or MK7 alone.


Some individuals suggest that only Vitamin K1 increases blood clotting (coagulation) while regular supplementing with K2 may even reduce coagulation (blood clotting). As a proof they suggest to take 500mcg of vitamin K2 MK7 every day for at least one week or longer and then pierce your finger with a needle to check how quickly the blood coagulates. If it doesn’t clot for a long time, they say, it so because of high levels of Vitamin K2. Therefore, in order to increase coagulation, they suggest to reduce K2 and either eat more kale and spinach or use Vitamin K1 supplementation to increase levels of K1.

On the other hand, there seems to be an evidence that Vitamin K in any form does clot blood. Also people who use K2 supplementation confirm it increases fibrinogen levels. However, the good thing about Vitamin K2 supplementation is that even if it is taken in high doses on a regular basis it doesn’t seem to increase coagulation but rather regulates it. But, if you are prone to excessive clotting or take warfarin you must be careful, have your fibrinogen level checked, and always consult medical practitioner before taking either Vitamin K1 or K2.


It is very interesting that in spite of all the warnings suggesting that people who are on blood thinning medications should avoid vitamin K, studies have found that supplementing with low-dose vitamin K (50-150 mcg per day) help stabilize the daily fluctuations in blood clotting time (INR) caused by varying dietary intakes of vitamin K.

For instance, according to the five-week study on 60 adults taking warfarin, when vitamin K intake was increased, INR became more stable. On the other hand, when vitamin K intake was reduced, INR became more unstable! (>)

Another study comparing the dietary habits of two groups of patients on warfarin (26 with stable and 26 with unstable control of anticoagulation) showed that the daily intake of vitamin K in those with unstable control was more than 2.5 times lower than that for patients with stable control during the two-week study. The researchers concluded that “Daily supplementation with oral vitamin K in unstable patients could lead to a more stable anti-coagulation response to warfarin.” (>)

In the article Is your Coumadin killing you? (The remarkable potential of vitamin K to stop arterial calcification) Dr. Ronald Hoffman wrote the following bottom line advice:

“If you’re at risk for heart disease, and especially if you’re taking a statin, you should be taking generous doses of Vitamin K2 MK7—from180 to 360 mcg per day. If you’re taking Coumadin (warfarin), don’t avoid vitamin K-rich foods, just consume moderate amounts on a regular basis and continue to monitor your INR via scheduled blood tests. Because it can be a little tricky, if you’re desirous of harnessing the benefits of MK7 supplements while on Coumadin, work with a nutritionally-oriented health professional to gradually ramp up while carefully following blood tests, if necessary adjusting your dose of medication to accommodate the additional vitamin K. It no longer makes sense to subject yourself to vitamin K deficiency, which could end up killing you just as assuredly as a blood clot!“(source >)

For instance, it is suggested to not take natural blood thinners such as Vitamin E, Serrapeptase, Cayenne pepper, etc. with blood thinners such as warfarin, aspirin, etc. as taken together they may increase the risk of bleeding. However, according to Dr. Robert Redfern, “Serrapeptase is safe to use with all drugs including warfarin, statins & aspirin.” (>) In addition, those who are on blood thinners and would like to use serrapeptase or other blood thinners at the same time, are often advised to take about 100mcg of vitamin K to reduce risk of bleeding. Vitamin K Helps, Not Harms Patients on Warfarin. A new clinical trial suggests that patients on warfarin benefit from increasing their vitamin K intake, as long as they keep their intake levels consistent (>).


Children under 1 year: 2-3 mcg

Children 1-3 years: 40 mcg

Children 4-13 years: 50-70 mcg

Adolescents 14-18 years: 80 mcg

Adult men: 130 mcg

Adult women: 100 mcg

Women who are pregnant or breastfeeding: 100 mcg


Although allergic reaction from supplementation is possible, no known toxicity is associated with high doses of the vitamin K1 or K2, and therefore no tolerable upper intake level (TUL) has been set.


Natural vitamin K in the form of vitamin K2 (MK4 and MK7) is safe, even in extremely high doses. The US Institute of Medicine (IOM) concluded that natural vitamin K has no known tolerable upper limit (TUL).

Blood clotting (coagulation) studies in humans using 45 mg (45,000 mcg!) per day of vitamin K2 (as MK4) and even up to 135 mg (135,000 mcg!) per day (45 mg three times daily) of K2 (as MK4), showed no increase in excessive blood clot risk.

In rats even doses as high as 250 mg/kg, body weight did not alter the tendency for blood-clot formation to occur. It means that in case of an average adult weighing about 150 pounds (70-80kg), that dose would be equivalent to approximately 17,000 mg of MK4, which is nearly 400 times more per day than the 45 mg/day used in clinical trials.

The only people taking warfarin (coumadin) should consult a knowledgeable practitioner before taking any vitamin K-containing dietary supplements.

On the other hand, unlike the natural forms of vitamin K1 and K2 and their various isomers, a synthetic type of vitamin K, vitamin K3 (menadione), is toxic at high levels, causes allergic reactions, haemolytic anaemia, and liver cytotoxicity.


For a very small number of people the MK7 form of Vitamin K2 may lead to trouble sleeping because it has been shown to boost the production of energy in the mitochondria (power stations) in nerve cells in the brain. With regards to cellular energy production Vitamin K2 actually has a similar function as CoQ10.

Although normally it is an excellent benefit as it improves cognitive function of the brain but in some individuals with genetic tendencies to store Vitamin K2 longer it may interfere with sleeping. For this reason it’s better to take vitamin K rather in the form of MK4 (due to much shorter life in the body) instead of MK7 and only with first meal.

In case it doesn’t solve the problem try to reduce the dosage and take magnesium citrate before bed.

The only problem with MK4 is that unlike MK7 it requires much higher supplemental dosage of 5-50 milligrams compared MK7 in which case 50-1000 micrograms is regarded as sufficient.


Both K1 and K2 are capable of reversing the anticoagulant activity of warfarin (Coumadin) which works by blocking recycling of vitamin K, so that the body and tissues have lower levels of active vitamin K.

Supplemental vitamin K reverses the vitamin K deficiency caused by warfarin, and therefore reduces the intended anticoagulant action of warfarin and related drugs.

However, sometimes small amounts of vitamin K are given orally to patients taking warfarin so that the action of the drug is more predictable.

The action of warfarin and vitamin K both require two to five days after dosing to have maximum effect, and neither warfarin nor vitamin K shows much effect in the first 24 hours.

If you are on a blood thinning medicine, such as warfarin (coumadin), consult your doctor before taking vitamin K supplements because it may affect the blood clots.

The newer anticoagulants apixaban, rivaroxaban and dabigatran work in a different way which do not interact with vitamin K, and may be taken with supplemental vitamin K.


For adults 100-300 mcg of K2 MK7 per day is considered a standard dose. However, 500mcg per day for certain conditions may be more effective in some cases, all the more since vitamin K is harmless in larger doses and they may provide additional benefit.

In case of children under 12 about 50 mcg per day is recommended.

If you suffer from osteoarthritis you may need 200 to 500mcg of K2 MK7 per day or for optimal results a combination of 200 to 500mcg of K2 MK7, 20 – 45 mg (20,000 – 45,000 mcg) of K2 MK4, 5,000 IU of D3, 2 times a day 400 mg magnesium citrate, 50 mg of calcium citrate (don’t take carbonate), 3 mg of boron, and 10-50 mg of zinc citrate.

Patients with chronic kidney disease may require doses as high as 500 mcg per day or even much higher. However, the use of mega doses in attempt to treat any condition should always be done under medical supervision, especially when patient is taking medication.


MK7 supplements can be either natural (for instance derived from natto) or synthetic. Synthetic MK7 supplements can be bioidentical or not. If you don’t have access to the natural then try to choose bioidentical option, if possible.

There are two chemical isomers of MK7: Trans and CIS. The Trans is found in nature and in food sources such as natto and other fermented products. CIS form, on the other hand, is not found in nature, and therefore we don’t know if it will produce exactly the same benefits in our body. For this reason it seems better to choose K2 MK7 supplements derived from fermented foods such as natto. If the label doesn’t indicate the source then I would assume it contains the probably inferior CIS form.

Those who wish to have an entirely natural supplement should opt for MK7 derived from the fermentation of soybeans, beans or chickpeas.

The K2 MK4 supplements available on the market are synthetic, but they are bioidentical, meaning they have the same chemical structure as the natural form.

The problem with MK4 supplements is that they are expensive due to the fact that this form should be taken in much higher dosage such as 20-50 mg per day as this strength was used in most studies that resulted in positive results.


Some sources suggest that we need about 50 mcg of Vitamin K2 MK7 per every 1000 IU of Vitamin D3. The optimal daily intake of vitamin D3 should be 5,000 IU therefore for this amount we need 250 mcg of vitamin K2 MK7 per day.

Please keep in mind that, as previously mentioned, supplement vitamin D without K2 can have disastrous effect, as it leads to calcification and increases demand for more Vitamin K2 in our body. Vitamin D must be also accompanied by good magnesium supplementation as without enough magnesium in the body it is useless and in addition leads to magnesium deficiency with its serious consequences.


Since some research seems to suggest that D3 is more effective if not taken at the same time as K2 is recommended to take Vitamin D3 with breakfast while Vitamin K2 with the next meal unless you experience sleep problems as a result of taking K2. In this case take it also in the morning (with breakfast).


However Vitamin K is a ‘fat soluble’ vitamin and therefore vitamin K supplements should be taken with some form of healthy fat such as coconut oil, olive oil, avocado, etc. for improved absorption. Combined with fat, vitamin K2 bioavailability (absorption) can rise to 13%.

Usually vitamin K supplements are combined with a fat base and if not try to have it with a meal which contains some fat. Vitamin K1 foods such as green vegetables should be consumed with some olive oil or flax oil.


Vitamin K is not very sensitive to heat, but it is extremely sensitive to light. So much so that when it is exposed to daylight, 80 percent of the vitamin K disappears within two days. Therefore, to make sure that your food source or supplements retain vitamin K content, keep them in the refrigerator or store in a cool dark place.


The synergistic relationship between vitamin D and vitamin K



– Akiyama N, Miyazawa K, Kanda Y, et al. Multicenter phase II trial of vitamin K2 monotherapy and vitamin K2 plus 1[alpha]-hydroxyvitamin D3 combination therapy for low-risk myelodysplastic syndromes. Leukemia Research. 2010;34(9):1151-1157. [article]

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– Iketani T, Kiriike N, Murray, et al. Effect of menatetrenone (vitamin K2) treatment on bone loss in patients with anorexia nervosa. Psychiatry Res. 2003;117(3):259-269. [article]

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Chris Masterjohn PHD December 9, 2016

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Am J Clin Nutr February 2003 vol. 77 no. 2 512-516

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