Your Guide to Vitamin K2: Benefits, Risks, Dosage

Medically Reviewed By Katherine Marengo LDN, R.D.
Was this helpful?
3

Vitamin K2 is a fat-soluble vitamin that is important for a variety of your body’s functions. Benefits can include stronger bones, teeth, lowered risk of heart disease, and more. It plays an especially important role in calcium deposition. You can get vitamin K2 through your diet or with supplements. It is found in some fermented and animal foods, such as natto, sauerkraut, organ meats, egg yolks, and certain cheeses.

This article discusses the benefits of vitamin K2. It also looks at the risks of getting too much or too little, dosage, and more.

What is vitamin K2?

there is an egg yolk against a blue background
Juan Moyano/Stocksy United

Vitamin K is a fat-soluble vitamin that comes in two major forms:

  • vitamin K1 (phylloquinone)
  • vitamin K2 (menaquinone)

Vitamin K2 is divided into the subtypes MK-2 through MK-14, with MK-4, MK-7, and MK-9 being the most well-studied.

Functions of vitamin K2

Vitamin K2 is essential for activating proteins involved with calcium, blood clotting, and heart health.

One of its main functions is to regulate the deposition of calcium. It removes calcium from your blood vessels and kidneys and deposits it into your teeth and bones.

Food sources of vitamin K2

Food sources high in vitamin K2 include:

  • natto
  • hard cheeses
  • eel
  • sauerkraut
  • miso
  • egg yolk
  • organ meats such as beef, chicken, and goose liver
  • grass-fed butter

Vitamin K2 for heart health

Vitamin K2 may lower your risk of cardiovascular damage and improve overall heart health. It activates matrix GLA protein (MGP), which keeps calcium deposits out of your arterial walls.

One of the main roles of vitamin K2 is to remove calcium from soft tissues, such as your arteries and kidneys. It is associated with decreased arterial calcification and stiffening.

Calcification of the arteries can lead to heart disease. A test called the calcium score test is used to measure calcification in your arteries. It is a predictive measure of your risk of heart disease.

A 2020 study found that people who had higher intakes of vitamin K2 had a lower risk of coronary heart disease. However, researchers in a 2021 review concluded that further evidence may be needed to establish more specific recommendations.

Learn more about heart healthy foods.

Vitamin K2 for bone health

Vitamin K2 promotes healthy bone mineral density by increasing mineralization and preventing bone loss. It activates a protein called osteocalcin, which helps bind calcium to bones.

Clinical trials have demonstrated that vitamin K2 maintains or even increases bone mineral density. It also may help prevent fractures, even in older patients who have already developed osteoporosis.

Several studies have also shown that poor vitamin K intake is linked to low bone mass, osteoporosis, and higher risk of fractures. Similarly, a 2021 meta-analysis found that higher dietary vitamin K intake was associated with a lower risk of fractures.

Researchers in a 2021 comprehensive review concluded that vitamin K2 plays an important role in the maintenance of bone and vascular health.

Vitamin K2 for weight loss

Vitamin K2 may play a role in weight loss, but current research is limited.

A 2018 randomized controlled trial looked at the effect of vitamin K2 in 214 post-menopausal women. It found that 180 micrograms (mcg) per day for 3 years resulted in a significant decrease in abdominal fat compared with a placebo.

The researchers also reported a significant increase in adiponectin, which is associated with insulin sensitivity.

Learn how to talk with your doctor about your weight.

Vitamin K2 against cancer

Some research suggests that vitamin K2 may inhibit the progression of liver cancer.

A 2018 review concluded that vitamin K2 could inhibit the growth of cancer cells in humans. This may make it a potentially useful approach for the prevention and clinical treatment of cancer.

Side effects and toxicity from vitamin K2

Vitamin K toxicity is rare. The only reported toxicity comes from menadione, a synthetic form of vitamin K3. This type of toxicity can cause:

  • yellowing skin
  • high levels of bilirubin in the blood
  • brain damage

Vitamin K toxicity can also occur in people taking warfarin or similar anticoagulants. Excessive blood clotting or hemorrhaging can occur if vitamin K intake is not closely monitored.

Even though no toxic dose has been established, it is important not to take excessive amounts of vitamin K.

Who should not take vitamin K2?

Vitamin K can interfere with warfarin (Coumadin) and similar anticoagulants, such as:

  • tioclomarol
  • phenprocoumon
  • acenocoumarol

Changes in vitamin K intake while taking these drugs can make them less effective, and may be dangerous.

Learn about other interactions of warfarin.

How much vitamin K2 do I need each day?

There are no specific recommendations for vitamin K2.

According to the National Institutes of Health, adequate intake of vitamin K for people aged 19 and older is 90 mcg for females and 120 mcg for males. Those with certain medical conditions may require more than this amount.

Contact your doctor before making significant changes to your diet. They can advise you on vitamin K2 supplementation as a treatment or as preventive therapy.

Learn about signs of vitamin K deficiency.

Is vitamin K2 supplementation worth it?

The 2020–2025 Dietary Guidelines for Americans notes that you should meet your nutritional needs primarily through foods. However, in some cases, dietary supplements may be useful when this is not possible.

Adults at risk for vitamin K deficiency include those taking certain medications and those with significant liver damage or disease. Also, people with fat malabsorption disorders may be at increased risk of vitamin K deficiency. These include conditions such as inflammatory bowel disease and cystic fibrosis.

Summary

Vitamin K2 prevents calcium from entering soft tissues and helps deposit it in your bones and teeth.

Vitamin K2 deficiency may cause calcification of the kidneys and blood vessels, increasing the risk of kidney stones or heart disease.

You can get vitamin K2 from your diet and through supplements. Changing your vitamin K2 intake can be dangerous when taking certain medications. Talk with your doctor before making changes to your diet.

Was this helpful?
3
Medical Reviewer: Katherine Marengo LDN, R.D.
Last Review Date: 2022 Nov 28
View All Food, Nutrition and Diet Articles
THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.