Vitamin K supplements
Vitamin K is a fat-soluble vitamin that you primarily get from food, such as green vegetables. Your gut bacteria also produce this vitamin.
But sometimes that is not enough and then supplements are a good addition.
This article will help you understand why vitamin K is important and when you need extra vitamin K.
What does vitamin K do for your body?
The main function of vitamin K is to support blood clotting, so that you do not lose too much blood in the event of an injury.
But it also contributes to the maintenance of strong bones.
If you want to buy vitamin K supplements, it is good to know that there are 2 types of vitamin K.
What is the difference between vitamin K1 and K2?
Vitamin K comes in two major forms: K1, which is primarily found in food, and K2, which is primarily produced by intestinal bacteria.
These are the main differences between K1 and K2:
Vitamin K1
- Also called phylloquinone, phytomenadione or phylloquinone
- It is the form of vitamin K that is primarily involved in blood clotting
- If you eat enough green leafy vegetables such as spinach, kale and broccoli, you usually get enough vitamin K1
Vitamin K2
- Also called menaquinone
- Contributes to blood clotting, but is also good for strong bones (1)
- May also help keep blood vessels supple, which is good for the heart*
- Produced by your gut bacteria, it is also found in fermented foods such as natto (fermented soybeans), hard cheeses, and some animal products such as eggs
Vitamin K in nutritional supplements
Vitamin K supplements are available with only vitamin K1 or K2, but also as a combination (K1 + K2).
You can also choose between tablets or drops. Liquid vitamin K is especially useful for babies, children, and people who have difficulty swallowing tablets.
K1 supplements
Are you looking for vitamin K1?
Then phytomenadione is the primary and most commonly used form for vitamin K1 supplements.
This form is often chosen because it is effective in supporting healthy blood clotting and is easily processed by the body.
K2 supplements
If you want to supplement vitamin K2, the most common forms are MK-7 and MK-4.
The difference between MK-4 and MK-7 is in the length of the molecular chain and the origin, but both fall under the broader category of menaquinone (K2).
- MK-7 is a special form of vitamin K2 that is better absorbed by your body and remains active longer than other forms of vitamin K2 (2). This makes it an effective choice for supplementation, as it stays in your system longer and can thus better deliver its benefits.
- MK-4 is also commonly used in bone health supplements, but higher doses are needed to achieve long-lasting effects as it breaks down quickly.
In short: Choose the MK-7 variant if you're looking to buy a vitamin K2 supplement. This form is better absorbed by your body and remains active longer. There aren't many options for vitamin K1. Phytomenadione is the most commonly used and effective form.
Vitamin D and K
Vitamin K supplements are often combined with vitamin D because they complement each other. Together, these two vitamins play an important role in bone health.
- Vitamin D helps absorb calcium from food, but without enough vitamin K, this calcium may build up in unwanted places, such as your blood vessels.
- Vitamin K helps move calcium to your bones and not into your arteries, where it can clog blood vessels.
This type of combination is often recommended for people who have both vitamin D and vitamin K deficiencies.
Do I need extra vitamin K?
Adults (men and women) need 70 micrograms of vitamin K daily.
Although you can easily get vitamin K1 and K2 from your diet, some people may find it helpful to consider a supplement.
For example, if you:
- You have a vitamin K deficiency, for example by not eating enough green vegetables.
- Taking certain medications. Some medications, such as blood thinners, can prevent your blood from clotting, reducing the amount of vitamin K available. (3)
- Taking antibiotics . These medications kill the good bacteria in your gut, which normally help make vitamin K. (3)
- If you have certain conditions , such as osteoporosis, your bones may need extra support.
- Are a woman and have (or have been) in menopause. A large-scale study of 16 different studies showed that women who had been in menopause and used vitamin K2 had a 57% lower risk of bone fractures compared to those who did not take vitamin K2. (1)
Note: If you are taking blood thinners or anticoagulants, always consult your doctor before taking a vitamin K supplement. Vitamin K can affect the way these medications work, making them less effective. Your doctor can advise you on whether it is safe to use vitamin K and, if so, the dosage.
Vitamin K for babies
Newborn babies do not yet have enough intestinal bacteria to produce the vitamin themselves and vitamin K is not passed on through the placenta.
That's why breastfed babies need extra vitamin K (150 micrograms per day) in the first three months. Special liquid vitamin K supplements are available for this purpose, which you can give to your baby in drops.
Please note : Formula usually contains sufficient vitamin K, but if a baby drinks less than 500 ml per day, additional vitamin K may be necessary.
What do I need, K1 or K2?
Whether you should buy vitamin K1 or K2 depends on your specific health situation and goals:
- K1 - Is ideal for supporting blood clotting.
- K2 - If you're interested in supporting your bones, vitamin K2 is an excellent choice.
Note : If you are unsure about which form of vitamin K you need, it may be helpful to discuss this with your doctor, especially if you are taking medications or have specific health conditions.
Sources used
- Ma, M., Ma, Z., He, Y., Sun, H., Yang, B., Ruan, B., Zhan, W., Li, S., Dong, H., & Wang, Y. (2022). Efficacy of vitamin K2 in the prevention and treatment of postmenopausal osteoporosis: A systematic review and meta-analysis of randomized controlled trials. Frontiers in Public Health , 10 . https://doi.org/10.3389/fpubh.2022.979649
- Sato, T., Schurgers, L. J., & Uenishi, K. (2012). Comparison of menaquinone-4 and menaquinone-7 bioavailability in healthy women. Nutrition Journal , 11 (1). https://doi.org/10.1186/1475-2891-11-93
- 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
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Where is vitamin K2 found and why is it important?
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 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. Read more Sources used Jadhav, N., Ajgaonkar, S., Saha, P., Gurav, P., Pandey, A., Basudkar, V., Gada, Y., Panda, S., Jadhav, S., Mehta, D., & Nair, S. (2022). Molecular Pathways and Roles for Vitamin K2-7 as a Health-Beneficial Nutraceutical: Challenges and Opportunities. Frontiers in Pharmacology, 13. https://doi.org/10.3389/fphar.2022.896920 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 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 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 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 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 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 Smajdor, J., Jedlińska, K., Porada, R., Górska-Ratusznik, A., Policht, A., Śróttek, M., Więcek, G., Baś, B., & Strus, M. (2023). The impact of gut bacteria producing long chain homologs of vitamin K2 on colorectal carcinogenesis. Cancer Cell International, 23(1). https://doi.org/10.1186/s12935-023-03114-2 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 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 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 Ma, M., Ma, Z., He, Y., Sun, H., Yang, B., Ruan, B., Zhan, W., Li, S., Dong, H., & Wang, Y. (2022). Efficacy of vitamin K2 in the prevention and treatment of postmenopausal osteoporosis: A systematic review and meta-analysis of randomized controlled trials. Frontiers in Public Health, 10. https://doi.org/10.3389/fpubh.2022.979649 Zhou, M., Han, S., Zhang, W., & Wu, D. (2022). Efficacy and safety of vitamin K2 for postmenopausal women with osteoporosis at a long-term follow-up: meta-analysis and systematic review. Journal Of Bone And Mineral Metabolism, 40(5), 763–772. https://doi.org/10.1007/s00774-022-01342-6 Kuang, X., Liu, C., Guo, X., Li, K., Deng, Q., & Li, D. (2020). The combination effect of vitamin K and vitamin D on human bone quality: a meta-analysis of randomized
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Vitamin K deficiency? Here's how to recognize it and what you can do about it.
Did you know that almost all babies in the Netherlands receive extra vitamin K because they can't produce it themselves yet? Fortunately, a deficiency is rare in adults, but it can occur in some situations. (1) You only need vitamin K in small amounts, but its role is significant. It helps your blood clot normally and contributes to strong bones. (2) In this article you can read when you need to be extra vigilant, how to recognize a deficiency and what you can do to quickly replenish your vitamin K. Vitamin K deficiency is rare in adults, but can occur with intestinal or liver problems, certain medications, a one-sided diet, or after surgery that affects fat absorption. Signs of deficiency include easy bruising, nosebleeds, bleeding from wounds, and bleeding gums; in the long term, bone weakening may also occur. Babies are routinely given extra vitamin K because they are born with low supplies and breast milk does not contain enough to prevent dangerous bleeding. Table of contents Symptoms of a Vitamin K Deficiency Main Causes of a Vitamin K Deficiency Step- by-step Plan for a Vitamin K Deficiency Vitamin K1 vs K2 (and MK-7) Product Tip How Much Do You Need? Vitamin K for Babies My Personal Advice Symptoms of a Vitamin K Deficiency Vitamin K is a fat-soluble vitamin. Your body can store it in fatty tissue and the liver, making deficiencies less likely to develop than with water-soluble vitamins (such as B and C). Therefore, a deficiency often develops slowly. If you do have a deficiency, you will often notice this in the following ways: Bruising easily Frequent nosebleeds Long-term bleeding from minor wounds Bleeding gums In the long term, a deficiency can also weaken your bones, because important bone proteins don't function properly without vitamin K. (3) Good to know : Without extra vitamin K, newborns can develop a deficiency that leads to vitamin K deficiency bleeding (VKDB). This can cause serious bleeding in the skin, intestines, or even the brain. Therefore, babies in the Netherlands are routinely given extra vitamin K. (1) Main causes of vitamin K deficiency If you're healthy and have a varied diet, a deficiency is almost non-existent. It's especially prevalent in babies and in a few specific situations in adults: Low Stores in Newborns - Babies are born with little vitamin K because little is passed across the placenta. (3) Low Vitamin K in Breast Milk - Breast milk does not contain enough Vitamin K for a baby. (4) Bile duct problems or cholestasis in babies - Liver or biliary diseases make the absorption of fat-soluble vitamins such as K difficult. (5) Bowel diseases in adults (such as celiac disease or Crohn's disease) - In these cases, fat is absorbed less well, and therefore also vitamin K. (6) Long-term use of antibiotics - These also kill the gut bacteria that normally produce K₂. (7) Poor fat absorption - In conditions such as IBD, cystic fibrosis, liver or bile problems, vitamin K is less well absorbed.(8) Bariatric surgery - After gastric bypass or sleeve surgery, the absorption of fat-soluble vitamins is reduced. (8) One-sided diet. Those who eat few green vegetables (K₁) or hardly any fermented/animal products (K₂) can develop deficiencies. (1) Severe liver disease (such as cirrhosis) - The liver plays a key role in processing K. When damaged, this goes wrong. (8) Medicines - Some medicines affect absorption or effect, such as vitamin K antagonists, certain anti-epileptics, painkillers and cholesterol-lowering agents. (9) Eating disorders (such as anorexia or bulimia) - A one-sided diet, vomiting or laxatives can cause a deficiency. (10) Step-by-step plan for a vitamin K deficiency Not sure if you're getting enough vitamin K? Don't worry: You can often get a lot from food or a simple supplement. Safety first - Do you have unexplained bleeding or are you taking blood thinners? Always consult your doctor first. Supplement - A supplement is the fastest way to replenish: 75–100 µg K1 or 90–180 µg K2 (preferably MK-7). Diet - Also eat green vegetables with some fat every day, and occasionally choose cheese, yogurt, eggs or natto. Address the root cause - Does the problem keep recurring, or are you experiencing intestinal or liver problems? Consult a doctor or dietitian for guidance. Vitamin K1 vs. K2 (and MK-7) Vitamin K is a collective name for several substances. The most important are K1 and K2. Both are fat-soluble and contribute to normal blood clotting. K1 is mainly found in green leafy vegetables like spinach and kale. It's absorbed quickly but doesn't stay in your body long. K2 is found in fermented foods like natto and cheese, and in smaller amounts in animal products. This form circulates longer and therefore reaches more tissues. Good to know : Within K2, MK-4 and MK-7 are the most well-known. MK-7 remains active the longest and is therefore the best used. (12) Product tip Our vitamin K supplement contains the potent form of K2, MK-7 , dissolved in high-quality olive oil . This ensures you're getting a highly absorbable form . How much do you need? The recommendation in the Netherlands is approximately 1 microgram of vitamin K per kilogram of body weight per day . For someone weighing 70 kilograms, this amounts to about 70 micrograms. (11) Separate guidelines apply for babies and young children. An upper limit has never been established. This shows that vitamin K is safe with a normal diet or supplementation. Please note : If you are using blood thinners (vitamin K antagonists, such as acenocoumarol or phenprocoumon), you should always consult your doctor or thrombosis service first, because vitamin K can affect their effectiveness. (6) Vitamin K in babies Babies begin life with almost no vitamin K. They receive little through the placenta, and breast milk contains too little. Therefore, all babies in the Netherlands are routinely given vitamin K supplements: Immediately after birth: 1 mg (often as an injection) And breastfed babies then 150 µg per day until 3 months (usually as drops) For bottle-fed babies, extra K is usually not necessary, because bottle feeding is enriched with vitamin K , but it is necessary if your baby gets less than 500 ml of bottle feeding per day (3)(4)(5) My personal advice I personally prefer a supplement that combines vitamin K and vitamin D. This is practical because you take both at once. Vitamin K contributes to normal blood clotting and, like vitamin D, helps keep your bones strong. I also remain a fan of the nutritional foundation : add some green vegetables to your plate (or smoothie) every day and a drizzle of olive oil for better absorption. Add a piece of cheese or an egg every now and then, and you've already got a good mix of K1 and K2. This way you combine the best of both worlds: Healthy food and a smart supplement that does exactly what it should do. 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. Read more Sources used Nutrition Center. (n.d.). Vitamin K for babies (JGZ information and advice). Retrieved August 27, 2025, from https://www.voedingscentrum.nl Nutrition Center. (n.d.). Vitamin K (function, sources, recommendations, and claims). Retrieved August 27, 2025, from https://www.voedingscentrum.nl IJland, MM, Pereira, RR, & Cornelissen, EA (2007). Incidence of late vitamin K deficiency bleeding in newborns in the Netherlands in 2005: evaluation of the current guideline. European Journal Of Pediatrics, 167(2), 165–169. https://doi.org/10.1007/s00431-007-0443-x Van Hasselt, P.M., De Koning, T.J., Kvist, N., De Vries, E., Lundin, C.R., Berger, R., Kimpen, J.L.L., Houwen, R.H.J., Jorgensen, M.H., & Verkade, H.J. (2008). Prevention of Vitamin K Deficiency Bleeding in Breastfed Infants: Lessons From the Dutch and Danish Biliary Atresia Registries. PEDIATRICS, 121(4), e857–e863. https://doi.org/10.1542/peds.2007-1788 Sankar, M. J., Chandrasekaran, A., Kumar, P., Thukral, A., Agarwal, R., & Paul, V. K. (2016). Vitamin K prophylaxis for prevention of vitamin K deficiency bleeding: a systematic review. Journal Of Perinatology, 36(S1), S29–S35. https://doi.org/10.1038/jp.2016.30 Turck, D., Bresson, J., Burlingame, B., Dean, T., Fairweather‐Tait, S., Heinonen, M., Hirsch‐Ernst, K.I., Mangelsdorf, I., McArdle, H.J., Naska, A., Nowicka, G., Pentieva, K., Sanz, Y., Siani, A., Sjödin, A., Stern, M., Tomé, D., Van Loveren, H., Vinceti, M., . . . Neuhäuser‐Berthold, M. (2017). Dietary reference values for vitamin K. EFSA Journal, 15(5). https://doi.org/10.2903/j.efsa.2017.4780 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 Eden, R. E., Daley, SF, & Coviello, J. M. (2023, September 8). Vitamin K deficiency. StatPearls - NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK536983/ 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 Urano, T., Shiraki, M., Ouchi, Y., Inoue, S., & Sasaki, T. (2015). Bone turnover and vitamin K status in anorexia nervosa. Clinical Nutrition , 34(3), 443–448. https://doi.org/10.1016/j.clnu.2014.05.002 Health Council (2017). Vitamin K for infants. Retrieved on August 27, 2025, from https://www.healthcouncil.nl/documents/advisory-reports/2017/04/11/vitamin-k-for-infants Sato, T., Schurgers, L. J., & Uenishi, K. (2012). Comparison of menaquinone-4 and menaquinone-7 bioavailability in healthy women. Nutrition Journal, 11(1), 93. https://doi.org/10.1186/1475-2891-11-93
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Vitamin K: The complete guide!
Vitamin K is an essential nutrient that plays a particularly important role in blood clotting in the body. It also has several other functions. In this article you will read about the functions of vitamin K, sources of vitamin K, the consequences of an excess or deficiency and more. Vitamin K supports blood clotting, bone health, and cardiovascular health; it is found as K1 (plant) and K2 (animal/fermented foods). Vitamin K deficiency is rare, except in infants and with prolonged antibiotic use; symptoms include bleeding, bruising, and delayed wound healing. Dietary vitamin K is better absorbed with fats; supplementation may be necessary for certain medical conditions or medications. Table of contents What is Vitamin K? What types of vitamin K are there? Differences between vitamin K1 and vitamin K2 The benefits of vitamin K in the diet Good for blood clotting Supports bone health Good for heart and blood vessels How much vitamin K do you need daily? Vitamin K for babies Vitamin K during pregnancy Where is vitamin K found? Vitamin K deficiency Why do babies have a vitamin K deficiency? Vitamin K deficiency with antibiotics Symptoms of vitamin K deficiency Too much vitamin K Vitamin K supplements What is Vitamin K? Vitamin K is a fat-soluble essential nutrient. Fat-soluble means it dissolves in fat, not in water. Therefore, it is better absorbed when combined with fat. In addition, your body stores the substance, rather than urinating it out when you have an excess. While there are no downsides to taking too much vitamin K, it's best not to overdo it with supplements, as with any fat-soluble vitamin. The harmful effects of such supplements are unclear. What types of vitamin K are there? There are two different types of vitamin K: Vitamin K1 (phytomenadione) Vitamin K2 (menaquinone) Vitamin K2 is a bit more complex, as there are several different forms of vitamin K2. The most common of these are: Vitamin K2 MK-4 Vitamin K2 MK-7 In addition, there are some forms of vitamin K2 (called menaquinones) such as MK-5, MK-6 and MK-8. However, these are much less common. [4] To give you an idea of the different types of vitamin K , we have worked this out in an image. Differences between vitamin K1 and vitamin K2 Both vitamin K1 and vitamin K2 have similar effects in the body. However, one form (vitamin K1) is broken down more quickly than the other (vitamin K2). For optimal body function, you want to get enough of both types. Here are some differences between the various forms of vitamin K. Vitamin K1: Also called phytomenadione Found mainly in plant foods (green leafy vegetables, broccoli) Is broken down faster by the body Vitamin K2 Also called menaquinone Comes in several forms: MK-7 is the most effective Mainly found in animal foods (meat, dairy, eggs) Also found in fermented products Can be produced by intestinal bacteria Is broken down more slowly by the body The Benefits of Vitamin K in the Diet While many vitamins have a wide range of functions, vitamin K is more concise. The vitamin primarily influences two specific bodily processes: blood clotting and bone health. Good for blood clotting The best-known function of vitamin K is its contribution to normal blood clotting. It supports proteins that, in turn, ensure proper blood clotting. This discovery was made by chance in the late 1920s when animals with a deficiency bleed more. The same was found to be true for humans. Supports bone health In addition, vitamin K supports bone health. It plays a role in both bone formation and bone maintenance. Vitamin K also plays a role in the absorption of calcium from the blood. Good for the heart and blood vessels Vitamin K2 supports calcium metabolism. A vitamin K2 deficiency from food can contribute to higher calcium levels in the blood vessels. This is not beneficial for blood vessel function[1]. How much vitamin K do you need daily? If you eat a healthy and varied diet, a vitamin K deficiency is rare. However, it can happen, for example, with long-term use of antibiotics or an inadequate diet. The Reference Intake (RI) for adults is 75 micrograms per day.[3] The optimal dosage of vitamin K can vary based on age and individual needs. General recommendations are provided below. Age/need Quantity Infants (0-6 months) Varies depending on the situation Infants (7-12 months) 2.5 micrograms per day Children (1-3 years) 30 micrograms per day Children (4-8 years) 55 micrograms per day Children (9-13 years) 60 micrograms per day Teenagers (14-18 years) 75 micrograms per day (boys) 60 micrograms per day (girls) Adults (18 years and older) 70-80 micrograms per day (men), 60-65 micrograms per day (women) Pregnant women 75 micrograms per day Women who are breastfeeding 75 micrograms per day Vitamin K for babies Newborn babies naturally have a vitamin K deficiency. Babies are therefore given vitamin K drops immediately after birth. This supports healthy blood clotting in the baby[2][3]. Breastfed babies should also receive 150 micrograms of vitamin K drops as a supplement from their doctor for the first 12 weeks. Formula already contains vitamin K, so supplementation isn't necessary, provided the baby drinks enough. Of course, discuss this first with a medical specialist. Vitamin K during pregnancy It's very important for a pregnant woman to get enough vitamin K during pregnancy. However, this isn't necessary for the baby, as vitamin K cannot be passed to the baby through the placenta. Getting enough vitamin K is important during pregnancy because a vitamin K deficiency from food can lead to bleeding, which you absolutely want to avoid. What foods contain vitamin K? Below is a table of some good food sources of vitamin K, with the amount of vitamin K per 100 grams. As you can see, the largest amounts are found in green leafy vegetables, herbs, and fermented products like Natto. Plant foods are rich in vitamin K1 , while animal foods and some fermented foods such as natto are rich in vitamin K2. Food Amount per 100 grams Parsley 1640 microgram Swiss chard 830 microgram Kale 817 microgram Natto 775 microgram Spinach 483 microgram Green cabbage 345 microgram Arugula 250 microgram Spring greens 186 microgram Broccoli 141 microgram Chicken liver 60 microgram Plums 59 microgram Asparagus 41 microgram Kiwi 40 microgram Egg yolk 38 microgram Soybeans 35 microgram Avocado 21 microgram Cucumber 16 microgram Pomegranate 16 microgram Bell pepper (green) 4 microgram Olives 1 microgram Pork 0.9 micrograms Helpful tip: Because vitamin K is a fat-soluble vitamin, it's important to combine these foods with some fats. A drizzle of extra virgin olive oil over the salad is not only delicious but also improves the absorption of vitamin K from the green leafy vegetables. Vitamin K deficiency If you eat a healthy and varied diet (including animal products), vitamin K deficiency is generally unlikely. This is different for babies. They do develop vitamin K deficiencies, which is why they receive a supplement at birth and afterward. Why do babies have a vitamin K deficiency? There is a possibility that a newborn baby has a vitamin K deficiency. This can be due to a number of causes: The placenta - Vitamin K cannot reach the baby through the placenta. Intestinal bacteria - Babies do not yet have enough intestinal bacteria, which means they cannot produce vitamin K themselves. Vitamin K deficiency with antibiotics A more common cause of vitamin K deficiency in adults is the use of antibiotics. Antibiotics kill all bacteria, but unfortunately, they also kill the good bacteria that produce vitamin K2 in your intestines. A vitamin K deficiency can therefore occur when killing these bacteria. This risk is greater with prolonged or regular use of antibiotics. Symptoms of vitamin K deficiency Because vitamin K contributes to normal blood clotting and bone health, a deficiency in dietary vitamin K may have the following consequences[2]: Spontaneous or severe bleeding (in infants) Delayed blood clotting Bruising more easily Wounds heal less quickly Long-term bone problems An excess of vitamin K There are no known cases of vitamin K overdose. Therefore, no maximum dosage has been established for vitamin K. People who use blood thinners should be careful when using vitamin K as a supplement.[3] Taking extra vitamin K can hinder the effectiveness of blood thinners. Therefore, do not take high doses of vitamin K if you are taking these types of medications and always consult a medical specialist.[4] Vitamin K supplements Vitamin K is a vitamin with important functions, such as promoting healthy blood clotting and maintaining strong bones. It is important that you get enough vitamin K through a healthy and varied diet rich in green leafy vegetables, other vegetables and sources such as eggs, meat and liver. An inadequate diet or medications can cause a deficiency and it is important to avoid this for healthy bones and good blood clotting. There are many vitamin K supplements on the market, but not all are equally absorbable. When taking a supplement, choose one that's easily absorbed and of good quality. Lauressa Lauressa studied Nutrition & Dietetics and also works as an editor. She enjoys delving deeply into topics related to healthy eating, mental well-being, and hormone balance. When she's not pursuing her passion for health, she enjoys being creative. Read more Sources www.ncbi.nlm.nih.gov/pmc/articles/PMC8596038/ www.ivg-info.nl/voedingssupplementen/vitamines/vitamine-k/vitamine-k-tekort / www.voedingscentrum.nl/encyclopedie/vitamine-k www.ncbi.nlm.nih.gov/books/NBK551578/
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