Vitamin K1 vs Vitamin K2: What's the Difference?

Controlled studies in people observed that vitamin K2 supplements generally improve bone and heart health, while vitamin K1 has no significant benefits for bone and heart health (Source). However, vitamin K2 is not available in plants.

What is vitamin K and what does it do?

Vitamin K is a nutrient that the body needs to stay healthy. It’s important for blood clotting and healthy bones and also has other functions in the body. If you are taking a blood thinner such as warfarin (Coumadin®), it’s very important to get about the same amount of vitamin K each day.

How much vitamin K do I need?

The amount of vitamin K you need depends on your age and sex. Average daily recommended amounts are listed below in micrograms (mcg).

Life Stage	Recommended Amount
Birth to 6 months	2.0 mcg
7–12 months	2.5 mcg
1–3 years	30 mcg
4–8 years	55 mcg
9–13 years	60 mcg
14–18 years	75 mcg
Adult men 19 years and older	120 mcg
Adult women 19 years and older	90 mcg
Pregnant or breastfeeding teens	75 mcg
Pregnant or breastfeeding women	90 mcg

 

What foods provide vitamin K?

Vitamin K is found naturally in many foods. You can get recommended amounts of vitamin K by eating a variety of foods, including the following:

• Green leafy vegetables, such as spinach, kale, broccoli, and lettuce
• Vegetable oils
• Some fruits, such as blueberries and figs
• Meat, cheese, eggs, and soybeans

Fats from pasture-raised animals* are going to be one of your best sources and will contain more K2 relative to confinement raised animals since they consume grass, which is rich in vitamin K1, which is converted to K2 by certain bacteria in the animal's gut. For example:

•Pasture-raised chicken yolk — 30 to 40 ug K2/yolk

•Confinement raised chicken yolk — 10 ug K2/yolk

Since animal fats are rich in K2 (especially food products from pasture-raised animals), you don't have to go crazy overboard in your fat consumption to consume sufficient amounts. K2 research and understanding is still in its infancy. But 100 to 200 ug daily intake is likely beneficial. Here are three examples, in addition to your other food sources:

1. 1 to 2 oz aged cheese, 2 pasture-raised eggs, 3 oz dark chicken meat
2. 1 to 2 oz aged cheese, 2 pasture-raised eggs, 1 oz beef liver
3. 1 oz aged cheese, 2 pasture-raised eggs, 3.5 oz ground pork

*If eggs are labeled as pasture raised it should mean they were laid by hens that spend their days outside on pasture where they can freely forage for bugs and grasses, exercise and enjoy lots of space to roam. That said, unlike the “free range” and “cage-free” label, “pasture raised” is not monitored by the U.S. Department of Agriculture. This means that “pasture raised” is a marketing claim. So, it’s up to us consumers to do our research and be sure the eggs we buy have the qualities that matter to us.

Vitamin K2 vs K1

Vitamin K is found in multivitamin/multimineral supplements. Vitamin K is also available in supplements of vitamin K alone or of vitamin K with a few other nutrients such as calcium, magnesium, and/or vitamin D. Common forms of vitamin K in dietary supplements are: 

• Vitamin K1 (phylloquinone and phytonadione): Found in plant foods like leafy greens.
• Vitamin K2 (menaquinone-4 and menaquinone-7): Found in animal foods and fermented foods (Source). 

Most people don't get enough of Vitamin K2 (Source). You can get vitamin K2 from high-fat dairy products, egg yolk, liver and fermented foods, such as sauerkraut and miso.

Controlled studies in people also observe that vitamin K2 supplements generally improve bone and heart health, while vitamin K1 has no significant benefits for bone and heart health (Source).

Here are some take home points about Vitamin K2:

• Vitamin K2 is important for metabolic health, bone and dental health, heart and kidney health, hormone production, and cancer prevention.
• Animal products and natto are the best sources of vitamin K2, but one form (MK-4) is only found in animal products.
• Eating animal fats is a practical way to consume this vital nutrient (plus, animal fats tend to be lower in PUFA and higher in SFA, further supporting metabolic health).

Vitamin D ensures that your blood levels of calcium are high enough to meet your body’s demands. However, vitamin D does not fully control where the calcium in your body ends up. That’s where vitamin K steps in.

Am I getting enough vitamin K?

Vitamin K deficiency is very rare. Most people in the United States get enough vitamin K from the foods they eat. Also, bacteria in the colon make some vitamin K that the body can absorb. However, certain groups of people may have trouble getting enough vitamin K:

• Newborns who don’t receive an injection of vitamin K at birth
• People with conditions (such as cystic fibrosis, celiac disease, ulcerative colitis, and short bowel syndrome) that decrease the amount of vitamin K their body absorbs
• People who have had bariatric (weight loss) surgery

What happens if I don’t get enough vitamin K?

Severe vitamin K deficiency can cause bruising and bleeding problems because the blood will take longer to clot. Vitamin K deficiency might reduce bone strength and increase the risk of getting osteoporosis because the body needs vitamin K for healthy bones.

What are some effects of vitamin K on health?

Scientists are studying vitamin K to understand how it affects our health. Here are some examples of what this research has shown.

Osteoporosis

Vitamin K is important for healthy bones. Some research shows that people who eat more vitamin K-rich foods have stronger bones and are less likely to break a hip than those who eat less of these foods. A few studies have found that taking vitamin K supplements improves bone strength and the chances of breaking a bone, but other studies have not. More research is needed to better understand if vitamin K supplements can help improve bone health and reduce osteoporosis risk.

Coronary heart disease

Scientists are studying whether low blood levels of vitamin K increase the risk of coronary heart disease, perhaps by making blood vessels that feed the heart stiffer and narrower. More research is needed to understand whether vitamin K supplements might help prevent heart disease.

Cancer
Interestingly, several studies have been done on vitamin K2 and certain types of cancer. Two clinical studies suggest that vitamin K2 reduces recurrence of liver cancer and increases survival times (Trusted Source, Trusted Source). Additionally, an observational study in 11,000 men found that a high vitamin K2 intake was linked to a 63% lower risk of advanced prostate cancer, whereas vitamin K1 had no effect (Trusted Source).

Can vitamin K be harmful?

Vitamin K has not been shown to cause any harm. However, it can interact with some medications, particularly warfarin (Coumadin®)—see the information below.

Are there any interactions with vitamin K that I should know about?

Yes, some medications may interact with vitamin K. Here are a few examples:

Warfarin (Coumadin®)

Vitamin K can have a serious interaction with the blood thinner warfarin (Coumadin®). If you take warfarin, make sure that the amount of vitamin K you consume from food and supplements is about the same every day. A sudden change in the amount of vitamin K you get can cause dangerous bleeding (if you consume less) or blood clots (if you consume more).

Antibiotics

Antibiotics can destroy the good bacteria in your gut. Some of these bacteria make vitamin K. Using antibiotics for more than a few weeks may reduce the amount of vitamin K made in your gut and therefore, the amount available for your body to use.

Bile acid sequestrants

Some people take bile acid sequestrants (such as cholestyramine [Questran®] and colestipol [Colestid®]) to lower blood cholesterol levels. These medications can reduce the amount of vitamin K your body absorbs, especially if you take them for many years.

Orlistat

Orlistat (Alli® and Xenical®) is a weight-loss drug. It reduces the amount of fat your body absorbs and can decrease the absorption of vitamin K.

Tell your doctor, pharmacist, and other healthcare providers about any dietary supplements and prescription or over-the-counter medicines you take. They can tell you if the dietary supplements might interact with your medicines or if the medicines might interfere with how your body absorbs, uses, or breaks down nutrients such as vitamin K.

Vitamin K and healthful eating

People should get most of their nutrients from food, advises the federal government’s Dietary Guidelines for Americans. Foods contain vitamins, minerals, dietary fiber and other substances that benefit health. In some cases, fortified foods and dietary supplements may provide nutrients that otherwise may be consumed in less-than-recommended amounts. For more information about building a healthy diet, refer to the Dietary Guidelines for Americans and the U.S. Department of Agriculture’s MyPlate.

Where can I find out more about Vitamin K?

• For general information on vitamin K:
  • Office of Dietary Supplements Health Professional Fact Sheet on Vitamin K
  • Vitamin K, MedLinePlus®
• For more information on food sources of vitamin K:
  • Office of Dietary Supplements Health Professional Fact Sheet on Vitamin K
  • U.S. Department of Agriculture’s (USDA) FoodData Central
  • USDA Nutrient Lists for vitamin K as either:
    • Phylloquinone, the form of vitamin K found in green leafy vegetables, listed by food or by content, or
    • Menaquinone, a form of vitamin K found in fermented foods and foods that come from animals, listed by food or by content
• For more advice on buying dietary supplements:
  • Office of Dietary Supplements Frequently Asked Questions: Which brand(s) of dietary supplements should I purchase?
• For information about building a healthy diet:
  • MyPlate
  • Dietary Guidelines for Americans

Disclaimer

This fact sheet by the Office of Dietary Supplements (ODS) provides information that should not take the place of medical advice. We encourage you to talk to your healthcare providers (doctor, registered dietitian, pharmacist, etc.) about your interest in, questions about, or use of dietary supplements and what may be best for your overall health. Any mention in this publication of a specific product or service, or recommendation from an organization or professional society, does not represent an endorsement by ODS of that product, service, or expert advice.

Updated: October 22, 2020

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