Vitamins and minerals – there’s a variety of them out there, and most of us have a general idea of what some of them do for our health. For example, vitamin A’s beneficial effects on eye health, calcium’s role in supporting bone health, or the importance of omega-3s on heart health. But what about vitamin K? Few of us have heard of this vitamin, and fewer still are aware of its effects on the body.
What is Vitamin K2?
First things first – vitamin K2 is just one piece of the puzzle. Vitamin K2 (or ‘menaquinones’) is actually a specific form of vitamin K, a fat-soluble vitamin that also comes in the form of vitamin K1 (or ‘phylloquinone’). (1) The different forms of vitamin K are not always distinguished when we talk about this vitamin, but it’s important to recognize their differences:
Vitamin K1 (Phylloquinone)
- Found in green leafy vegetables, vegetable oils, and select fruits (1)
- Can be converted to vitamin K2 (in the form of MK-4) within the body (1)
Vitamin K2 (Menaquinones)
- Found in meat, dairy products, eggs, and fermented foods (1)
- Comes in a variety of forms, identified as MK-4 through to MK-13 (1)
- Some forms can be produced in small amounts by bacteria residing in our intestinal tracts (1)
Why is Vitamin K2 Important?
Vitamin K is traditionally known for its role in coagulating (or clotting) blood, a crucially important function that prevents us from bleeding out from a single cut or scrape. (1) This role is primarily performed by vitamin K1. (2) While vitamin K2 can also play a role in coagulation, it has several other functions that can have a significant impact on our health. (2)
Osteoblasts are cells within the body that are responsible for building bone. (3) These cells secrete a protein called osteocalcin, which needs to be activated by – you guessed it – vitamin K2. (3) Once activated, osteocalcin actually helps to bring calcium into the bones, which is then incorporated into the structure of our bones by osteoblasts. (3) Without the help of vitamin K2, the calcium that we consume from calcium-rich foods would not make it into our bones, resulting in decreased bone density or osteoporosis. Ensuring adequate intake of calcium-rich foods is important, but we also need to make sure our body has what it needs to actually use that calcium to strengthen our bones.
Vitamin K2 has also been found to work with vitamin D3 (which helps to increase the amount of calcium our bodies absorb) to actually inhibit the action of osteoclasts, which would normally result in the loss of some bone mass. (3)
The activation of osteocalcin by vitamin K2 is not only beneficial for bone health; once activated, osteocalcin is able to activate a protein called matrix gla protein, or MGP. (3) This protein has been found to actually remove calcium that can accumulate in our arteries and veins – excessive accumulation of calcium (or calcification) in these areas can eventually form atherosclerotic plaques and may lead to the development of heart disease. (3,4) Interestingly, vitamin K1 has not been found to have the same effect. (4)
How Can You Include More Vitamin K2 in Your Diet?
Vitamin K2 is largely found in animal-based or fermented foods, while vitamin K1 is found in plant-based foods, primarily leafy green vegetables. (1) While most of us are capable of converting some vitamin K1 to vitamin K2 within our bodies, the evidence is mixed on whether this is enough. (5)
Different forms of vitamin K2 are found in different foods. Vitamin K2 MK-4 is found only in animal-based foods, such as butter, eggs, cheese, dark poultry meat, and liver. (5) Vitamin K2 MK-7 is found in fermented foods, including tempeh (pictured above), miso, natto, sauerkraut, and aged cheese. (5) Incorporating foods from one or both of these groups may help to increase your daily vitamin K2 intake.
When consuming foods that contain vitamin K, be sure to include a source of fat to increase the absorption – this may not be necessary when consuming animal products that naturally contain fat (such as butter), but including a fat source with your leafy greens or when consuming fermented foods can help to increase absorption.
Given the challenges of including enough vitamin K2-containing foods to promote any appreciable increase in vitamin K2 intake, it may be beneficial for some people to include a vitamin K2 supplement. (5) A Registered Dietitian can help you determine if incorporating a vitamin K2 supplement is necessary or safe (sudden changes in vitamin K consumption are not recommended for those on blood thinners).
If you’re curious about vitamin K2, Nutrition Assessment Clinic can help you optimize your intake through the use of foods and supplements, as needed.
- National Institutes of Heath – Office of Dietary Supplements. (2020). Vitamin K – Fact sheet for health professionals. Retrieved from https://ods.od.nih.gov/factsheets/vitaminK-HealthProfessional/
- Halder, M., Petsophonsakul, P., Akbulit, A. C., Pavlic, A., Bohan, F., Anderson, E., Maresz, K., Kramann, R., & Schurgers, L. (2019). Vitamin K: Double bonds beyond coagulation insights into differences between vitamin K1 and K2 in health and disease. International Journal of Molecular Sciences, 20(4), 896. https://doi.org/10.3390/ijms20040896. Retrieved from https://www.mdpi.com/1422-0067/20/4/896/htm
- Jacob, A. (2013). Vitamin K2 – A little-known nutrient can make a big difference in heart and bone health. Today’s Dietitian, 15(6):54. Retrieved from https://www.todaysdietitian.com/newarchives/060113p54.shtml
- Cook, D. (2019). Vitamin K2 benefits. What are they? Retrieved from https://www.dougcookrd.com/vitamin-k2-benefits-what-are-they/
- Norris, J. (2014). Vitamin K. Retrieved from https://veganhealth.org/vitamin-k/#fn1
Author: Mikaela Horton, MHSc(c), RD for nutritionassessment.com