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.

What is 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 [1].

Vitamin K2 is also important for regulation of cell growth, and maintenance of the arterial wall [2].

Vitamin K2 is also known as menaquinones [3].

There’s two main types of Vitamin K2: MK-4 and MK-7 [3].

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 [3].

Humans can partly convert Vitamin K1 to K2 in the body [3].

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.

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

How it Works

Vitamin K is a cofactor for γ-glutamyl carboxylase, 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 [4].


  • 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) 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) [5].

Osteocalcin needs K2 to become fully activated and bind to calcium [5].

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 [6] and improve bone strength [7].

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 [8].

Vitamin K2 deficiency can lead to arterial defects and osteoporosis [2].

Low levels of Vitamin K were linked to increased inflammation, fractures, and bone pain [9].

2) 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% [10].

Vitamin K2 prevents calcium from being deposited in the arteries, which helps prevent heart disease [11].

Drugs that block vitamin K accelerate the hardening of the arteries in mice [12].

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 [13].

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 [14].

3) 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 [15, 16].

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

4) Decreases Inflammation

High Vitamin K levels are associated with lower inflammation rates [17].

K2 was able to decrease CRP [17].

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 [18].

5) 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 [19].

In people with rheumatoid arthritis, a daily dose of 45mg Vitamin K2 was shown to prevent other diseases [20].

6) Boosts Mitochondrial Function

Science Magazine[21]

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 [22].

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

Vitamin K2 with an electron has anti-oxidant properties [23] and can prevent glutathione depleted neuronal death in cultured neurons [24].

7) May Help Some Cancers

Higher vitamin K2 (but not K1) intake was linked to a 63% lower risk of advanced prostate cancer [25].

In lung cancer cell lines, Vitamin K2 was helpful in destroying cancer [26].

Studies show the clinical benefits of using Vitamin K2 for the treatment of patients with acute leukemia and myelodysplastic syndromes [26].

Clinical trials have shown that vitamin K2 reduces the recurrence of liver cancer and increases survival times (hepatocellular carcinoma) [27, 28, 29].

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) [30].

Vitamin K2 goes well with other treatments such as chemotherapy, where it was shown to help prevent the growth of tumors and cancerous cells [31].

An increase in dietary intake of vitamin K is associated with a reduced risk of cancer in a Mediterranean population at high cardiovascular disease [32].

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 [33].

8) 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 [34].

Studies have found that patients with early-stage Alzheimer’s disease consumed less vitamin K than did cognitively intact control subjects [35].

Vitamin K’s effects are hypothesized as a result of “sphingolipid metabolism” [34].

Vitamin K2 (MK-4) was found to be positively correlated with sulfatides and sphingomyelin [34].

It’s not clear precisely what these do in the brain [36], but when I first took vitamin K2, it helped my brain function.

9) 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 [32].

10) Lowers Insulin Resistance

Vitamin K2 supplementation for 4 weeks increased insulin sensitivity in healthy young men (mechanism was through carboxylation of Osteocalcin) [37].

A different study found insulin resistance to decline in older men, but not women [38].

11) 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 the increased onset of Cardiovascular Disease, Diabetes, Chronic Kidney Disease, bone fractures and even mental disorder [39].

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 [40].

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 [4142].

On the other hand, MGP is a strong inhibitor of vascular calcification, but only when it’s carboxylated [43].

Vitamin K2, but not K1, is needed to carboxylate MGP, which helps avoid calcification in the arteries [43].

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.

Vitamin K2 Deficiency Risks

Population-based studies have linked a high dietary intake of preformed vitamin A (retinol) to a greater risk of osteoporosis and hip fracture [44].

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 [45].

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 [23].

  • Liver disease [46].
  • People with inflammatory bowel disease or cystic fibrosis [47, 48].
  • Babies who are exclusively breastfed [49].

Vitamin K2 Foods

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 [50].

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 [51].

Specifically, Lactic Acid Bacteria produce K2, in the form of MK4 [23].

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 [52]
  • Pork: 0.2-9.9 micrograms/100g [52]
  • Beef: 1.1-9.3 micrograms/100g [52]
  • Egg yolks: 15.5 micrograms/100g [53]
  • Salami: 9 micrograms/100g [54]
  • Milk: 0.8-1.0 [53]
  • Cheese: 4.7-10.2 micrograms/100g [54]
  • Sauer Kraut: 0.4 micrograms/100g [54]
  • Natto (fermented soybeans): 939-998 micrograms/100g of MK7 [50].

Other general categories of food:

  • Fermented foods [23]
  • Liver and other organs [53]
  • Dairy products from grass-fed animals (cheese, curds, yogurt, milk) [50, 55, 52].

Interesting fact: Small Intestinal Bacterial Overgrowth (SIBO) causes a leaky gut and an increase in vitamin K1 [56].

Vitamin K2-producing bacteria

Menaquinones produced by bacterial species commonly used in industrial food fermentations [57]: 

Species/subspeciesFood useMK-5MK-6MK-7MK-8MK-9MK-10
Lactococcus lactis subsp. lactisCheese, buttermilk, sour cream, cottage cheese, cream cheese, kefir√√
Lactococcus lactis subsp. cremorisCheese, buttermilk, sour cream, cottage cheese, cream cheese, kefir√√
Leuconostoc lactisCheese√√
Brevibacterium linensCheese
Brochontrix thermosphactaMeat√√
Hafnia alveiCheese
Staphylococcus xylosusDairy, sausage√√
Staphylococcus equorumDairy, meat√√
Arthrobacter nicotinaeCheese√√
Bacillus subtilis “natto”Natto√√
Propionibacterium shermaniiCheese


Vitamin A and D work synergistically with vitamin K2 [58].


There is no known toxicity associated with this vitamin [59].

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