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I’ve been taking Vitamin K2 for over 5 years now, and it’s one of the most stable supplements in my regimen.  I really like how it makes me feel and it has a great safety profile.

Introduction to Vitamin K2

Vitamin K2, also known as the menaquinones, is involved in blood clotting, bone health, and the regulation of some cellular functions in the human body [R].

Vitamin K2 is also important for regulation of cell growth, and maintenance of the arterial wall [R].

Vitamin K2 is also known as menaquinones [R].

There’s two main type of Vitamin K2: MK-4 and MK-7 [R].

Vitamin K2 in the form of MK-7 has a much longer half-life than the synthetic K1, which means it stays in your system for longer [R].

Humans can partly convert Vitamin K1 to K2 in the body [R].

Vitamin K2 is preferred by the liver tissues and this may be produced as MK4 by the animal from K1 or may be of bacterial origin [R].

Note that there aren’t many clinical trials on K2, but nevertheless, it’s a good supplement to “Selfhack” with.

How Vitamin K2 Works

Vitamin K is a cofactor for γ-glutamylcarboxylase, which increases the rate of the carboxylation of glutamic acid to γ-carboxyglutamic acid.

The carboxylation of glutamic acid makes it possible for proteins to be able to bind with calcium, which in turn is important in blood clotting (coagulation). Calcium binding is also an integral part of bone health and strength [R].

Vitamin K2 Snapshot


  • Promotes strong bones and teeth.
  • Improves Cognitive performance.
  • Decreases inflammation and helps some autoimmune conditions.
  • Reduces risk for heart disease and improves circulation.


  • People on blood thinners should limit their K2 intake to amounts typically found in the diet.

Benefits of Vitamin K2

1) Vitamin K2 Helps Prevent Osteoporosis and Improves Bone Health

In order for your bone to take in calcium, it needs something called osteocalcin to bind to the calcium, which is released by bone cells (osteoblasts) [R].

Osteocalcin needs K2 to become fully activated and bind to calcium [R].

Vitamin K2 maintains and improves bone mineral density. In a study done on post-menopausal women, participants with a higher level of Vitamin K2 helped prevent bone fractures [R] and improve bone strength [R].

If the bone isn’t taking in the calcium, then more of it is getting stuck in your arteries, which cause them to harden.

Studies have found up to an 80% reduction in fractures in osteoporosis patients with K2 supplements [R].

Vitamin K2 deficiency can lead to arterial defects and osteoporosis [R].

Low levels of Vitamin K were linked to increased inflammation, fractures, and bone pain [R].

2) Vitamin K2 Helps Prevent Heart Disease

There’s an association between higher intake of vitamin K2 and lower risk of heart disease. For every 10 micrograms of K2 consumed per day, the risk of heart disease was reduced by 9% [R].

Vitamin K2 prevents calcium from being deposited in the arteries, which helps prevent heart disease [R].

Drugs that block vitamin K accelerate the hardening of the arteries in mice [R].

People with the highest intake of Vitamin K2 were 52% less likely to develop calcification of the arteries and had a 57% lower risk of dying from heart disease, over a 7-10 year period [R].

In a 3 year, double-blinded randomized controlled trial, 500μg/d of K1 supplementation was associated with reduced calcification of the arteries in the heart [R].

3) Vitamin K2 Makes Your Teeth Stronger

As mentioned, K2 is important for osteocalcin to work fully.

Osteocalcin stimulates the growth of new dentin, which makes your teeth stronger [R, R2].

If I ever floss and start to get pain in my gums, K2 takes it away pretty fast.

4) Vitamin K2 Decreases Inflammation

High Vitamin K levels are associated with lower inflammation rates [R].

K2 was able to decrease CRP [R].

Vitamin K2 is also involved with inflammatory cytokines.

Poor levels of Vitamin K are associated with a high level of cytokines, which cause bone loss. However, even when patients took Vitamin K2 supplements, their cytokine concentration did not change [R].

5) Vitamin K2 May Help Autoimmune Conditions

Vitamin K2 administration was shown to help fight against an animal model of a brain autoimmune condition similar to multiple sclerosis [R].

In people with rheumatoid arthritis, a daily dose of 45mg Vitamin K2 was shown to prevent other diseases [R].

6) Vitamin K2 Boosts Mitochondrial Function

Science Magazine(R)

Vitamin K2 helps transport electrons in the mitochondria, similar to ubiquinone, which helps boost mitochondrial function and create energy.

However, in mice liver cells, it wasn’t able to replace all the functions ubiquinone (R).

In a fly model of Parkinson’s, K2 was able to help by improving the mitochondria (R).

Vitamin K2 with an electron has anti-oxidant properties [R] and can prevent glutathione depleted neuronal death in cultured neurons [R].

7) Vitamin K2 May Help Some Cancers

Higher vitamin K2 (but not K1)  intake was linked to a 63% lower risk of advanced prostate cancer [R].

In lung cancer cell lines, Vitamin K2 was helpful in destroying cancer [R].

Studies show clinical benefits of using Vitamin K2 for the treatment of the patients with acute leukemia and myelodysplastic syndromes [R].

Clinical trials have shown that vitamin K2 reduces recurrence of liver cancer and increases survival times (hepatocellular carcinoma) [R, R2, R3].

Meta-analyses failed to find any benefits regarding recurrence of liver cancer after a year of supplementation, but slight benefits in years 2 and 3 (3-year study) [R].

Vitamin K2 goes well with other treatments such as chemotherapy, where it was shown to help prevent the growth of tumors and cancerous cells [R].

An increase in dietary intake of vitamin K is associated with a reduced risk of cancer in a Mediterranean population at high cardiovascular disease [R].

Technical: Growth arrest-specific gene 6 (Gas6) is a protein that is dependent on Vitamin K. Gas6 kills cancer cells and stops cancer growth. Without Vitamin K, Gas6 would not be able to function [R].

8) Vitamin K Helps the Brain

Vitamin K2 is the principal form of vitamin K that the brain uses.

Vitamin K2 (MK-4) was found to represent greater than 98% of total vitamin K in the brain, irrespective of age [R].

Studies have found that patients with early-stage Alzheimer’s disease consumed less vitamin K than did cognitively intact control subjects [R].

Vitamin K’s effects are hypothesized as a result of “sphingolipid metabolism” [R].

Vitamin K2 (MK-4) was found to be positively correlated with sulfatides and sphingomyelin [R].

It’s not clear precisely what these do in the brain [R], but when I first took vitamin K2, it helped my brain function.

9) Vitamin K2 Lowers the Risk of Dying From All Causes

An increase in dietary intake of vitamin K is associated with a reduced risk of dying from all causes in a Mediterranean population at high cardiovascular disease [R].

10) Vitamin K2 Lowers Insulin Resistance

Vitamin K2 supplementation for 4 weeks increased insulin sensitivity in healthy young men (mechanism was through carboxylation of Osteocalcin) [R].

A different study found insulin resistance to decline in older men, but not women [R].

11) Vitamin K2 MAY Prevent Some of the Negative Effects of Statins and Vegetable Oils

Vegetable oils, Statins and warfarin share, in part, a common mechanism to inhibit vitamin K2-dependent processes, which is interpreted to lead to increased onset of Cardiovascular Disease, Diabetes, Chronic Kidney Disease, bone fractures and even mental disorder (R).

Therefore, taking K2 can help with the side effects of these drugs and oils.

Vitamin K2 and Varicose Veins

Some hypothesize that vitamin K can help with varicose veins (R).

Based on what I’m reading, the study that people are citing doesn’t say vitamin K2 helps.

The study says that there is increased MGP (Matrix GLA Protein) in varicose veins as a result of calcification in the blood vessels, and it’s thought that this contributes to varicose veins (RR).

On the other hand, MGP is a strong inhibitor of vascular calcification, but only when it’s carboxylated (R).

Vitamin K2, but not K1, is needed to carboxylate MGP, which helps avoid calcification in the arteries (R).

It could be that by shunting calcium to the bones instead of arteries, it can reduce varicose veins.  But given the MGP is involved in causing varicose veins, it might be a net value of zero or less.

Bottom line: I don’t see sufficient evidence that K2 will help varicose veins.  You can infer based on the evidence that is available that it can make varicose veins better or worse.


Any issue that is worsened by calcification may be helped by K2.  For example, kidney stones, heel spurs or even skin health, but I haven’t seen studies for these.

Increasing Vitamin K2 Naturally

K2 is generally higher in the fat of animals, especially those that are grass fed. K1 is found in plants.

Dietary intake of vitamin K2 accounts for up to 25% of total vitamin K intake [R].

Humans can partly convert vitamin K1 to K2 in the body, but the conversion process is inefficient.

Vitamin K2 is also produced by gut bacteria in the large intestine [R].

Specifically, Lactic Acid Bacteria produce K2, in the form of MK4 [R].

Here are the levels of K2 from animals in the US that aren’t grass fed.  Japan has higher values for all of these foods, while the Netherlands is mixed.

If you want to find out how to use these vitamin K rich foods to make healthy and delicious meals check out the Lectin Avoidance diet and its cookbook.

  • Ghee from grass fed animals
  • Chicken: 13.6–31.6 micrograms/100g [R]
  • Pork: 0.2–9.9 micrograms/100g [R]
  • Beef: 1.1–9.3 micrograms/100g [R]
  • Egg yolks: 15.5 micrograms/100g [R]
  • Salami: 9 micrograms/100g [R]
  • Milk: 0.8–1.0 [R]
  • Cheese: 4.7–10.2 micrograms/100g [R]
  • Sauer Kraut: 0.4 micrograms/100g [R]
  • Natto (fermented soy beans): 939-998 micrograms/100g of MK7 [R].

Other general categories of food:

  • Fermented foods [R]
  • Liver and other organs [R]
  • Dairy products from grass-fed animals (cheese, curds, yogurt, milk) [R] [R] [R].

Interesting fact: Small Intestinal Bacterial Overgrowth (SIBO) causes a leaky gut and an increase in vitamin K1 [R].

Vitamin K2 Deficiency Risks

Population-based studies have linked high dietary intake of preformed vitamin A (retinol) to a greater risk of osteoporosis and hip fracture (R).

When I take retinol (vitamin A), it makes me become deficient in K2.

This is because vitamin A competes with Vitamin K2 and Vitamin D3, both of which are important for bone health.

Broad-spectrum antibiotics can contribute to K2 deficiency as a result of killing bacteria that produce K2 [R].

If you are taking a bile acid sequestrant such as cholestyramine, that will increase your need for K2, since K2 is absorbed in the bile [R].

Bacteria Which Produce Vitamin K2

Menaquinones produced by bacterial species commonly used in industrial food fermentations [R]:  

Species/subspecies Food use MK-5 MK-6 MK-7 MK-8 MK-9 MK-10
Lactococcus lactis subsp. lactis Cheese, buttermilk, sour cream, cottage cheese, cream cheese, kefir √√
Lactococcus lactis subsp. cremoris Cheese, buttermilk, sour cream, cottage cheese, cream cheese, kefir √√
Leuconostoc lactis Cheese √√
Brevibacterium linens Cheese
Brochontrix thermosphacta Meat √√
Hafnia alvei Cheese
Staphylococcus xylosus Dairy, sausage √√
Staphylococcus equorum Dairy, meat √√
Arthrobacter nicotinae Cheese √√
Bacillus subtilis “natto” Natto √√
Propionibacterium shermanii Cheese

K2 Synergies

Vitamin A and D work synergistically with vitamin K2 [R].

Safety of Vitamin K2

There is no known toxicity associated with this vitamin [R].

Buy Vitamin K2

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  • donnagail

    I’m using extra aged dutch gouda for my k2 mk4…i eat an ounce a day…should i eat it all at once or spread throughout the day so it will be in my bloodstream over time? I don’t have a gallbladder so i’m not sure bile will be present exactly when i eat it…should i take a bile acid supplement together with my gouda? is an ounce too much? I also chose gouda to try to reach my calcium needs as a postmenopausal woman, for CLA, and for some animal-sourced Vit A. Is this a good plan? I have clogged arteries and I’m also using raw cacao powder and serrapeptase to try to help unclog them.

  • Wal

    Any thoughts on how K2 would effect ADHD would love any kind of feedback on it

  • ROB

    Be careful with MK7. I find it builds up in the system and once it gets to a certain level I experience severe anxiety. This is not a problem with MK4. If you react this way only take MK7 every third or fourth day.

  • Jennifer Cowan

    what the heck are MK4 and MK7? Were we talking about K2? I am confused. I am wondering if I even need K2. I am 57 and working. Father has had a 5-way heart bypass and corroded op. Brother had a stroke recently 53yr and one corroded is 100% blocked the other about 80%blocked, too risky to operate. my other brother and sister have very high cholesterol. mine is 6.1

  • ruth kogon

    it is surprising that the article says that there is no known toxicity with taking K2 . I and many otheres have quite a severe skin reaction.
    I would like to keep taking K2 for its benefits but how can i avoind the skin reaction?

  • John hayword

    Vitamin k2 also boost testosterone by bypassing the HTPA loop. It boost testosterone through “osteocalcin” which activates the G proteins in the testis. The leydig cells in testis through the activation of the G protein GRPC6a cause the leydig cells to release testosterone. This is actually one of the only ways to activate testosterone without the HTPA axis. I use Vitamin K2 as a bonus with my weightlifting stack and the results are great.

  • NehaShah

    Great article! I have just recently learned about k2 and have been curious about it. K2 seems to be a bit of a mystery to a lot of people. From my knowledge base, K2 can still affect coagulation to some extent even though k1 and k2 are very different. However, K2 can also aid in preventing artery calcification from Warfarin (the main anti-clotting med). I would advise people to speak to their doctor regarding the use of K2 if they are prescribed anti-coagulants…it may be totally safe and I believe it is beneficial but these anti-coagulants are extremely sensitive and I would make sure its safe.

  • Phil Alcoceli

    The best source of MK4 I’ve found is from Relentless Improvement. I have received many of the benefits listed here. It’s truly a “sleeper” supplement! (not very impressive on the outside but excellent inside)

  • Jeff

    I’m 79 years old and have two cardiac stents to keep my heart working. I take one baby aspirin each day as a blood thinner. I have spinach salads three or four times a week. How dangerous is it for me to take Vitamin K-2? Should I avoid it?

  • Samantha

    I’m a little confused regarding the vitamin A.. It states that it competes with vitamin K and vitamin D in one section and then in another section it says it works synergistically with vitamin K and vitamin D. So, do I take my vitamin A along with my vitamin K2 and vitamin D?

    1. Nattha Wannissorn

      Competes for absorption and also when it changes gene expression, but it works together inside the cells. These things often come together in foods anyway so make sure you have enough of each.

  • Will Schlinsog

    Have you heard that there is a naturally occurring Vitamin K2 MK4 source which is higher than goose liver and way better than natto.
    Walkabout Health Products CFO Dr. Will Schlinsog

    1. Kelly

      Emu oil is higher than all of them.

  • CM

    I have been taking Cholestyramine. So K2 is absorbed by it? I wonder what else that CSM is absorbing? Hmmmmm. Any other stuff I should know about?

    1. Joseph M. Cohen
  • Alan

    Is it possible that vitamin K2 can cause insomnia by directing calcium from the brain to the bones?

    1. Joseph M. Cohen

      Anything is possible, but that’s unlikely

  • zmkd

    I like that you prefer MK-4 over MK-7. I’ve never been convinced that MK-7 is preferable, even though the vast majority of health bloggers say it is. They say that MK-7 has a longer half-life in the blood… but what if that’s because the body is greedily using up the MK-4 first?

  • Joseph M. Cohen


    1. Jake

      Considering you’re Jewish, you should check your genome if possible for any heterozygous Ashkenazi mutations.

      I’m really curious if you have any.

      1. Joseph M. Cohen

        Yes, I’m Ashkenazic, I should check…

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