What is vitamin K2?

What is vitamin K2?

Posted by Melanie Winter

Table of Contents

    Vitamin K2: What Is It Good For?

    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 generally more bioavailable than MK-4, resulting in higher serum levels after consumption of foods rich in MK-7.2,3

    Commercial supplements containing MK-7 may be derived from fermented ingredients including chickpeas and soy proteins derived from natto, providing vegetarian and vegan options.2 Synthetic or nature identical forms of MK-7 are also used in supplements.

    Vitamin K2 activates proteins involved in a number of important body processes. Vitamin K2 contributes to normal blood coagulation (clotting), supports blood health and helps support cardiovascular system health.

    Vitamin K2 also plays a role in supporting bone mineralisation and bone strength.

    What Foods Are High in Vitamin K2?

    One of the richest food sources of vitamin K2 is the traditional Japanese food natto (soybeans fermented with Bacillus subtilis). Natto naturally contains vitamin K2 as menaquinone-7 (MK-7).2

    Other food sources of vitamin K2 include fermented cheeses, curd and small amounts found 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 or avocado may assist absorption.5

    What Is Vitamin K2 Good For?

    Supporting bone health and mineralisation

    Vitamin K2 plays a role in supporting bone health, bone strength and bone mineralisation.

    Bone remodelling is regulated by osteoblasts, which help form new bone, and osteoclasts, which are involved in normal bone turnover.6 Osteoblasts produce osteocalcin, a protein involved in binding calcium to the bone matrix. Vitamin K2 is required to activate osteocalcin.6

    Due to its role in activating osteocalcin, vitamin K2 helps support bone mineralisation and healthy bone formation.6

    One trial investigated the effect of daily vitamin K2 (MK-7) supplementation on osteocalcin functionality.3,7 The study included 60 postmenopausal women aged 50 to 69 years who consumed 0, 50, 100 or 200 mcg of MK-7 daily for 4 weeks alongside a controlled diet.

    Results of the study suggested that daily doses of 100 mcg or more improved osteocalcin carboxylation, a marker associated with bone mineralisation.7

    Supporting cardiovascular system health

    Vitamin K2 contributes to normal blood coagulation (clotting), supports blood health and helps maintain cardiovascular system health.

    Research has explored the role of vitamin K dependent proteins in calcium regulation within the body.6 Vitamin K2 is involved in activating matrix GLA protein (MGP), which plays a role in calcium metabolism within blood vessels.6

    Through activation of vitamin K dependent proteins, vitamin K2 may help support healthy calcium utilisation in the body.6

    Maintaining appropriate intake of nutrients including calcium and vitamin K2 may help support cardiovascular system health as well as bone health.6

    Supporting blood health

    Vitamin K’s primary role is in the manufacture of clotting factors including prothrombin and clotting factors VII, IX and X.1 All forms of vitamin K contribute to normal blood clotting.1

    Vitamin K supplements may interact with anticoagulant medications such as Warfarin and Coumadin. Individuals taking these medications should seek advice from their healthcare professional before using vitamin K supplements.

    Vitamin K2 Uses

    Supporting bone health

    Vitamin K supplements may support bone mineralisation in postmenopausal women by supporting osteocalcin activity.1

    Research has explored the role of vitamin K2 in supporting healthy calcium balance and bone health.3 Some studies have investigated the relationship between vitamin K2 supplementation and bone health markers in postmenopausal women.8,9

    One study found that Vitamin K2 as menaquinone-7 (MK-7) supplementation helped support bone health in healthy postmenopausal women.8 Another study investigated the effect of MK-7 on age related changes in trabecular bone in postmenopausal women.9

    Research suggests that higher vitamin K intakes may help support biochemical markers involved in bone mineralisation.6

    Other key uses

    Bone support

    Newly made osteocalcin requires vitamin K2 to become activated and bind calcium, supporting bone mineralisation.6

    Supporting blood vessel and artery health

    Matrix GLA protein (MGP), a vitamin K dependent protein produced by vascular smooth muscle cells, plays a role in calcium regulation within the cardiovascular system.6

    Supporting calcium function

    Calcium contributes to the structure and strength of bones and teeth and supports healthy muscle contraction.6

    Dosage

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

    In Australia, the recommended adequate intake (AI) for vitamin K is 70 mcg per day for adult men and women.11 Requirements may vary depending on age, dietary intake and individual health needs.  

    Some studies have investigated daily intakes of 180 mcg of vitamin K2 in relation to bone and cardiovascular health markers.6

    This is the amount provided in Australian NaturalCare Vitamin K2 180 mcg.  

    Vitamin K2 Deficiency

    Low dietary intake, impaired absorption or certain digestive conditions may contribute to lower vitamin K status.10

    Signs associated with vitamin K deficiency may include:10

    • Reduced bone mineralisation
    • Easy bruising
    • Heavy menstrual bleeding

    Always read the label and follow the directions for use. If symptoms persist, talk to your health professional. This information is general in nature and is not intended to replace medical advice.

    References

    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. Sponsor MenaQ7.
    3. Sato, T. et al. 2012. Comparison of menaquinone-4 and menaquinone-7 bioavailability in healthy women. Nutrition Journal.
    4. Kresser, C. 2017. Vitamin K2: Are You Consuming Enough?
    5. Vitamin K. Linus Pauling Institute. Oregon State University.
    6. Maresz, K. 2015. Proper Calcium Use: Vitamin K2 as a Promoter of Bone and Cardiovascular Health.
    7. Inaba, N. et al. 2015. Low-dose daily intake of vitamin K2 (menaquinone-7) improves osteocalcin y-carboxylation.
    8. Knapen, M, HJ. et al. 2013. Three-year low-dose menaquinone-7 supplementation helps decrease bone loss.
    9. Ronn, S, H. et al. 2016. Vitamin K2 prevents age-related deterioration of trabecular bone microarchitecture.
    10. Lab Tests Online. 2017. Vitamin K Deficiency.
    11. eatforhealth.gov.au. (n.d.). Nutrients. Nutrient Reference Values for Australia and New Zealand. NHMRC
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