Waar zit vitamine K2 in en waarom is het belangrijk?

Where is vitamin K2 found and why is it important?

Geschreven door: Ebrina van der Bijl

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Gepubliceerd op:

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Leesduur: 8 min

Vitamin K2 is vitamin K1's lesser-known sibling. While K1 is primarily found in green vegetables, K2 is found in fermented products and animal foods. Together, they form the vitamin K family, but each has its own role in the body.

In this article I will tell you exactly what vitamin K2 is and in which foods you can find it.

Vitamin K2 plays a crucial role in the proper use of calcium, which contributes to strong bones and helps prevent calcification of blood vessels.

Important dietary sources include fermented products (such as natto and cheeses) and animal products (such as liver, egg yolks, and butter from grass-fed cows).

MK-7 supplements may be useful for the elderly, postmenopausal women, or people who eat a diet low in K2, when consulted with a physician.

Table of contents
What is Vitamin K2? MK-4 and MK-7: The Most Important Forms of Vitamin K2 Why is K2 Important? Where is Vitamin K2 Found? 1. Fermented Foods 2. Animal Products 3. Your Intestines How Much Vitamin K2 Do You Need? K2 Deficiency: How Do You Know? Supplements: Necessary or Not? Things to Keep in Mind When Taking K2 Supplements: Vitamin K2 MK-7 Premium

What is vitamin K2?

Vitamin K is actually a collective name for different forms of vitamin K, of which these are the most important:

  • Vitamin K1 (phylloquinone) - This is mainly found in green vegetables like spinach, kale, and broccoli. K1 helps with blood clotting , so your wounds heal well and you don't lose too much blood.
  • Vitamin K2 (menaquinones) - Found in fermented and some animal products. K2 ensures that calcium reaches the right places in your body, such as your bones, and not in your blood vessels.

MK-4 and MK-7: The most important forms within vitamin K2

It's good to know that vitamin K2 itself is a collective term. K2 comes in several forms, from MK-4 to MK-13. MK-4 (from meat and dairy) and MK-7 (from fermented products) are particularly important.

MK-7 remains in the body longer and is therefore often considered the most effective form .

Want to know more? In this article, I'll focus on K2, specifically MK-4 and MK-7. Want to learn more about the other forms? Then you can read more in my complete guide to vitamin K.

Why is K2 important?

Vitamin K2 helps your body use calcium properly . It activates special proteins in your body that determine where calcium goes.

Two of those proteins are particularly interesting:

  • Osteocalcin – This protein helps calcium be stored in your bones and teeth. It contributes to strong bones, which becomes more important as you age.
  • Matrix Gla protein (MGP) – This protein actually helps prevent calcium from building up in places you don't want it, such as in the walls of your blood vessels. (1)(2)

What foods contain vitamin K2?

You will mainly find vitamin K2 in:

1. Fermented foods

These are the richest sources of vitamin K2, especially in the MK-7 form:

  • Natto (fermented soybeans, popular in Japan) is the absolute best: It is very rich in MK-7. (3)
  • Hard cheeses such as Gouda or Edam, and also some soft cheeses such as blue cheese, provide a lot of MK-7 and also some other forms such as MK-8 and MK-9. (4)(5)
  • Fermented vegetables like sauerkraut also contain K2, but in smaller amounts than natto or cheese. (6)

2. Animal products

Animal foods mainly provide MK-4, a shorter-acting form of vitamin K2:

  • Liver (especially chicken or goose) is rich in MK-4
  • Egg yolks , especially from free-range eggs, also contain a good amount of
  • Butter and cream from grass-fed cows contain more MK-4 than dairy from barn-fed cows (7)

3. Your intestines

The bacteria in your intestines also make some K2, but your body doesn't absorb it very well .

Your intestines contain numerous bacteria that can produce menaquinones (forms of vitamin K2) (such as MK-7, MK-8). However, it is not certain that this intestinal contribution is sufficient to meet your body's needs. (8)

  • Scientific research shows that these bacteria, such as Lactobacillus and Bacteroides, produce K2 in your large intestine, but that location is not ideal for absorption . (9)
  • A recent study suggests that a small portion can be absorbed, but it is usually too little to really rely on . (10)

So for enough K2 you need foods like natto, cheese or egg yolks, or possibly a supplement.

How much vitamin K2 do you need?

A general guideline for adults is approximately 70 micrograms of vitamin K per day . This is a recommendation for all forms of vitamin K combined .

There is no separate recommended daily allowance (RDA) for vitamin K2 yet. However, extensive research is underway, particularly on the MK-7 form.

These studies show that doses of 70 to 180 micrograms of K2 (MK-7) per day are commonly used. These amounts are considered safe.

K2 deficiency: How do you notice it?

A serious vitamin K deficiency is rare. If it does occur, it's usually manifested in bleeding symptoms, such as:

  • Bruising easily
  • Nosebleeds
  • Bleeding from minor wounds

Severe deficiencies occur primarily in newborns or people with severe absorption problems . Sometimes the use of certain medications can also be the cause.

For most people, it's not a real deficiency, but rather a low K2 intake . You won't notice this immediately, but it can have an impact in the long run.

For example, researchers see links between low K2 and:

  • Weaker bones
  • Accumulation of calcium in the blood vessels
  • Possible effects on cardiovascular health (11)

Are you unsure if you're getting enough, or are you experiencing symptoms such as frequent bruising? Always consult a doctor.

Supplements: Necessary or Not?

Do you regularly eat hard cheeses or fermented products like natto? Then you're probably already getting a good amount of K2 from your diet.

But there are situations where some extra support can be useful:

  • For example , older people and postmenopausal women are more likely to experience bone loss (12)(13).
  • Even if you eat few animal or fermented products , it may be more difficult to get enough K2.

In such cases, some people opt for a supplement, often as an addition to their diet.

When taking K2 supplements, keep this in mind:

Do you think you're not getting enough vitamin K2 from your diet? A supplement might be an option. It's important to keep a few things in mind:

  • Choose MK-7 – This is the most commonly used form in supplements. MK-7 remains active in your body longer than MK-4, making it often the preferred choice.
  • Combine with vitamin D – Vitamin K2 and D work together to help your body use calcium. So make sure you also get enough vitamin D through sunlight, oily fish, or possibly a supplement. (14)
  • Be careful with medications – Are you taking blood thinners? Then a K2 supplement can be dangerous, as it can affect the effectiveness of your medication. Only use it if your doctor explicitly approves it.
  • Dosage – Many supplements contain 70–180 micrograms of MK-7 per day. These are dosages often used in research and are considered safe. Always start with a low dosage so you can get a feel for how your body reacts.
  • Not necessary for everyone – For most people, a varied diet with dairy, cheese or fermented products is sufficient.

Vitamin K2 MK-7 Premium

A healthy and varied diet remains the foundation. However, a Vitamin K2 MK-7 supplement can be a valuable addition in some situations. This product is designed to support your vitamin K2 intake safely and effectively.

It contains the MK-7 form, known for its longer duration of action in the body and good absorption. The combination with high-quality olive oil optimally supports absorption.

Ebrina van der Bijl - Natural Performance

Ebrina van der Bijl

Ebrina is a nutritionist with a deep commitment to healthy eating and a sustainable lifestyle, based in beautiful Portugal. Her passion for natural and organic products is at the heart of her work. With a background in Nutrition & Dietetics and experience in product development and writing, she translates complex scientific information into practical advice for a balanced lifestyle.

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Sources used

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  2. Yan, Q., Zhang, T., O'Connor, C., Barlow, J. W., Walsh, J., Scalabrino, G., Xu, F., & Sheridan, H. (2023). The biological responses of vitamin K2: A comprehensive review. Food Science & Nutrition, 11(4), 1634–1656. https://doi.org/10.1002/fsn3.3213
  3. Tsukamoto, Y., Ichise, H., Kakuda, H., & Yamaguchi, M. (2000). Intake of fermented soybean ( natto ) increases circulating vitamin K 2 (menaquinone-7) and γ-carboxylated osteocalcin concentration in normal individuals. Journal Of Bone And Mineral Metabolism, 18(4), 216–222. https://doi.org/10.1007/s007740070023
  4. Vermeer, C., Raes, J., Van 't Hoofd, C., Knapen, M. H. J., & Xanthoulea, S. (2018). Menaquinone Content of Cheese. Nutrients, 10(4), 446. https://doi.org/10.3390/nu10040446
  5. Altuncu, V., Kaymaz, A., Filiz, B. E., Demiralay, E. Ç., & Taş, T. K. (2024). Evaluation of MENAQUINONE‐7 and fat‐soluble vitamin production by starter cultures during fermentation in dairy products using RPLC method. Food Science & Nutrition, 12(11), 9822–9833. https://doi.org/10.1002/fsn3.4474
  6. Tarvainen, M., Fabritius, M., & Yang, B. (2018). Determination of vitamin K composition of fermented food. Food Chemistry, 275, 515–522. https://doi.org/10.1016/j.foodchem.2018.09.136
  7. Elder, S. J., Haytowitz, D. B., Howe, J., Peterson, J. W., & Booth, S. L. (2005). Vitamin K Contents of Meat, Dairy, and Fast Food in the US Diet. Journal Of Agricultural And Food Chemistry, 54(2), 463–467. https://doi.org/10.1021/jf052400h
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  9. Yan, H., Chen, Y., Zhu, H., Huang, W., Cai, X., Li, D., Lv, Y., Si-Zhao, N., Zhou, H., Luo, F., Zhang, W., & Li, The Relationship Among Intestinal Bacteria, Vitamin K and Response of Vitamin K Antagonist: A Review of Evidence and Potential Mechanism. Frontiers in Medicine, 9. https://doi.org/10.3389/fmed.2022.829304
  10. Zhang, T., O'Connor, C., Sheridan, H., & Barlow, J. W. (2024). Vitamin K2 in Health and Disease: A Clinical Perspective. Foods, 13(11), 1646. https://doi.org/10.3390/foods13111646
  11. Zhao, Q., Li, Q., Rashedi, M. H., Sohouli, M., Rohani, P., & Velu, P. (2024). The effect of vitamin K supplementation on cardiovascular risk factors: a systematic review and meta-analysis. Journal Of Nutritional Science, 13. https://doi.org/10.1017/jns.2023.106
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