What is vitamin K2?

There are two main forms of Vitamin K2, menaquinone-4 (MK-4) and menaquinone-7 (MK-7). 2  Studies have shown that MK-7 is the more absorbable form of vitamin K2 resulting in increases in serum levels of MK-7 in the blood stream after consumption of foods rich in the MK-7 form of vitamin K2. The MK-4 form of vitamin K2 did not contribute to vitamin K2 status in the blood stream, demonstrating poorer bioavailability. 2,3


Due to bacterial processes of production, commercial supplements in the market of MK-7 can be derived from fermented ingredients from chickpeas and soy proteins derived from natto, therefore providing vegetarian and vegan options.2 However, these can be very costly, which is why synthetic forms of MK-7 are also used in supplements.


Vitamin K2 activates proteins which play a role in a number of key body processes. Vitamin K2 contributes to blood coagulation (clotting) thereby supporting blood health. It has also been found to contribute to inhibiting calcium deposits in the arteries and blood vessels2 which supports and maintains cardiovascular system health.

Vitamin K2 also has an essential role in supporting bone mineralisation






The best food source of vitamin K2 is the traditional Japanese food natto (soybeans which have been fermented with Bacillus subtilis). Natto contains a significant amount of natural vitamin K2 as menaquinone–7 (MK-7).2 And its consumption has been linked to bone health and reduced risk of fractures. Japanese postmenopausal women who consumed the most natto, the richest food source of vitamin K2, had less bone loss over time.4


Other food sources of vitamin K2 are fermented cheeses, curd, and small amounts in egg yolk.2


As vitamin K is a fat-soluble vitamin, taking a vitamin K2 supplement with a meal containing healthy fats such as olive oil, avocado and coconut oil will improve absorption.5                        




Vitamin K2 helps support bone health:

Vitamin K2 supplements (MK-7) could beneficially affect bone health.

Bone remodelling is regulated by osteoblasts—cells that build up the skeleton and form new bone— and osteoclasts—cells that break down the skeleton.6 

Osteoblasts produce osteocalcin. Osteocalcin is a protein hormone found in bone and is also known as bone gamma-carboxyglutamic acid-containing protein (BGLAP). It helps take calcium from the blood circulation and binds it to the bone matrix. Osteocalcin influences and supports bone mineralization through its ability to bind to hydroxyapatite, the mineral component of bone.6 

The newly made osteocalcin, however, is inactive, and it needs vitamin K2 to become fully activated and bind calcium.

Due to vitamin K2’s role in activating osteocalcin it plays a pivotal role in supporting bone health and maintaining bone mineralisation, formation and building.6 

One trial investigated the effect a daily dose of vitamin K2 (MK-7) on improving osteocalcin functionality.3,7  This study took 60 post-menopausal women aged 50-69 years old who were allocated to one of four dosage groups and consumed 0, 50, 100 or 200mcg of menaquinone-7 (MK-7) daily for 4 weeks with a controlled diet.

Results of the study showed that taking doses 100 micrograms and over a day of MK-7 improved osteocalcin functionality and therefore supported bone health.7


Supporting cardiovascular system health and function:

Vitamin K2 contributes to blood coagulation (clotting), supports blood health and is becoming recognized for its pivotal role in supporting bone mineralisation, as well as helping to reduce calcium deposits in the arteries and blood vessels2 thereby supporting cardiovascular system health.

Recent scientific evidence suggests that excess calcium can reduce cardiovascular system health and can be connected to the deposition of calcium in blood vessel walls and soft tissues.6

Vitamin K2 is associated with helping to reduce arterial calcification and arterial stiffening due to the excess deposition of free-floating calcium.6

Through its activation of vitamin K– dependent proteins, vitamin K2 can optimize calcium use in the body, preventing any potential health impacts associated with increased calcium intake including the excess deposition of calcium on the arterial walls.6 

By striking the right balance of intake of calcium and K2, it can be possible to support cardiovascular system health and also support healthy bones.6

An adequate intake of vitamin K2 has been shown to lower the risk of vascular damage because it activates matrix GLA protein (MGP) in blood vessels which inhibits the deposits of calcium on the walls.6


Supporting blood health – Is vitamin K2 a blood thinner?

Vitamin K’s primary role is in the manufacture of clotting factors like prothrombin and clotting factors VII, IX, and X.

All three forms of vitamin K (1, 2 and the synthetic 3) function similarly in helping with blood clotting, but vitamin K1 seems to have more functions overall rather than K2.1


Both vitamins K1 and K2 may affect the way medications can work that thin the blood (anti-coagulants) which includes Warfarin and Coumadin. They can reduce the effect of blood thinners.




Vitamin K2 and its uses:

  • Supporting bone health: Vitamin K supplements support bone mineralisation in postmenopausal women by boosting blood levels of osteocalcin and also by decreasing calcium excretion through the urine.
  • Studies have shown that vitamin K2 can slow the process of bone resorption and decrease risk of fracture. Vitamin K2 supports both bone and cardiovascular health via regulation of calcium balance in the body. It aids calcium in reaching the bone and then being incorporated into the bone, where it is needed for bone building and strengthening. Furthermore, it helps reduce calcium deposition in the cardiovascular system.3
  • One study found that Vitamin K2 menaquinone-7 (MK-7) supplementation helped decrease bone loss in healthy postmenopausal women.8
  • Another study found that Vitamin K2 as menaquinone-7 (MK-7) prevented age-related deterioration of trabecular bone at the tibia in postmenopausal women.9
  • Research suggests that vitamin K intakes that are much higher than the current recommendations improve biochemical markers of bone formation (mineralisation) and can help promote bone density.


Other Key Uses:

  • Bone: Newly made osteocalcin (a protein hormone found in bone) is inactive, and it requires vitamin K2 to become fully activated and bind calcium, therefore supporting bone mineralisation. 6   
  • Supports blood and cardiovascular health:  The vitamin K–dependent protein, matrix GLA protein (MGP) is a central calcification inhibitor produced by the cells of vascular smooth muscles and helps to regulate calcium in the cardiovascular system.6   
  • Indirectly supporting other roles of Calcium:  (1) providing structure and strength to bones and teeth, (2) supporting healthy muscle contraction, (3) helps prevent dietary calcium deficiency.6



Recommended daily intake of vitamin K is 120 mcg/day (US) for men, 90 mcg/day (US) for women, and 30-55 mcg/day (US) for children.2

The researchers found that a daily dose of 180 mcg was enough to improve bone mineral density, bone strength, and cardiovascular health.6

The therapeutic dose is 180mcg.



Vitamin K2 Deficiency:

Lack of good health of the gut microbiota or low levels of microbiota can cause deficiency of vitamin K2 as they can produce vitamin K2. Modern lifestyles with unhealthy eating patterns and consumption of junk food changes gut microbiota, as well as those with digestive conditions, mild gastrointestinal tract inflammation and those who have not been able to restore good gut flora after antibiotic use.10


Signs of vitamin K2 Deficiency include:10

  • Lack of bone mineralisation
  • Increase calcium in the blood stream
  • Easily bruising including the appearance of ruptured capillaries
  • Heavy menstrual periods



1.Murray, M, T.  1996. Encyclopedia of Nutritional Supplements. The Essential Guide for Improving Your Health Naturally. Three Rivers Press.


2. MenaQ7, Vitamin K2 as MK-7. SponsorMenaQ7. Date viewed: 15.11.19. Accessed from: http://menaq7.com/




3. Sato, T. et al. 2012. Comparison of menaquinone-4 and menaquinone-7 bioavailability in healthy women. Nutrition Journal. Sponsor not listed. Date viewed: 15.11.19. Accessed from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3502319/pdf/1475-2891-11-93.pdf


4. Kresser, C. 2017. Vitamin K2: Are You Consuming Enough? Date viewed: 15.11.19. Accessed from: https://kresserinstitute.com/vitamin-k2-consuming-enough/


5. Vitamin K. Linus Pauling Institute. Micronutrient Information Center. Oregon State University. Date viewed: 15.11.19. Accessed from:  https://lpi.oregonstate.edu/mic/vitamins/vitamin-K


6. Maresz, K. 2015. Proper Calcium Use: Vitamin K2 as a Promoter of Bone and Cardiovascular Health. Sponsor not listed. Date viewed: 15.11.19. Accessed from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4566462/  


7. Inaba, N. et al. 2015. Low-dose daily intake of vitamin k2 (menaquinone-7) improves osteocalcin y-carboxylation: A double blind, randomised controlled trial. Journal of Nutritional Science and Vitaminology. Vol. 61. pp:471-480.


8. Knapen, M, HJ. Et al. 2013. Three-year low-dose menaquinone-7 supplementation helps decrease bone loss in healthy postmenopausal women. Sponsor not listed. Date viewed: 15.11.19. Accessed from: https://www.ncbi.nlm.nih.gov/pubmed/23525894


9. Ronn, S, H. et al. 2016. Vitamin K2 (menaquinone-7) prevents age-related deterioration of trabecular bone microarchitecture at the tibia in postmenopausal women.

European Journal of Endocrinology.  Sponsor not listed. Date viewed: 15.11.19. Accessed from:  https://eje.bioscientifica.com/view/journals/eje/175/6/541.xml


10: Lab Tests Online.2017. Vitamin K Deficiency. Sponsor not listed. Date viewed: 15.11.19. Accessed from: https://labtestsonline.org/conditions/vitamin-k-deficiency