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August 17, 2021


Lindsay Delk, RDN
Benefits Of Vitamin K

Fact Checked By Lindsay Delk, RDN
 August 17, 2021

Benefits Of Vitamin K

Although you don’t hear as much about vitamin K, it’s still a vitally important nutrient.

Research estimates that up to 31% of Americans have a vitamin K deficiency or insufficiency (1).

Vitamin K is one of four fat-soluble vitamins, along with vitamins A, D, and E.

Two Types of Vitamin K

The two primary types of vitamin K are vitamin K1 (phylloquinone) and vitamin K2 (menaquinone).

  • Vitamin K1 – Your body needs vitamin K1 for blood clotting (2).
    Prothrombin is a protein that is dependent on vitamin K for effective blood clotting. Blood clotting causes a wound to stop bleeding and start healing, inside and outside your body. Vitamin K1 is found in plants, especially green leafy vegetables.
  • Vitamin K2 – Vitamin K2 is important for bone health and preventing the calcification of arteries (3).
    A buildup of calcium in the walls of the arteries can lead to heart disease. Vitamin K2 is produced by bacteria that live in your intestines and is found in some animal-based foods and fermented foods.
  • There are two important subtypes of vitamin K2: MK-4 and MK-7. MK-4 and MK-7 are the most studied subtypes of vitamin K2.

    MK-7 is the most effective type of vitamin K2 because of its higher bioavailability and longer half-life. Higher bioavailability means that more of the vitamin is absorbed and used by your body. A longer half-life means that the vitamin stays in your body longer (4).

    Research shows that MK-7 improves bone quality and strength (5).


Benefits of Vitamin K2

  • Heart disease prevention – Vitamin K2 helps calcium get into the bone instead of your arteries.

    A buildup of calcium in the walls of your arteries and other blood vessels can lead to the hardening of arteries and heart disease (6).

    This calcification is a risk factor for coronary heart disease because it reduces the elasticity of your aorta and arteries (7).

Matrix-Gla protein (MGP) requires vitamin K and decreases the buildup of calcium in your blood and soft tissues.

One large study of men and women aged 55 years and older showed that people eating the highest amounts of vitamin K2 had a 57% lower risk of coronary heart disease death than those eating the lowest amounts of vitamin K2 (8).

  • Healthy bones – Vitamin K is required by certain proteins to make bone (9).

    Osteocalcin is a protein that requires vitamin K to produce healthy bone tissue and prevent the weakening of bones.

    The European Food Safety Authority even approved a health claim for vitamin K that “a cause and effect relationship has been established between the dietary intake of vitamin K and the maintenance of normal bone.” (10)

Some studies show that people who eat more vitamin K have stronger bones and are less likely to break a hip (11).

Recent research found that people who ate the highest amount of vitamin K had a 22% less risk of broken bones than people who ate the lowest amount of vitamin K (12).

Vitamin K Deficiency and Insufficiency

While getting enough vitamin K in your diet isn’t difficult, certain situations can raise your risk of vitamin K deficiency or insufficiency.

Causes of deficiency

  • Malabsorption disorders – If you have certain digestive or malabsorption disorders, such as celiac disease, Crohn’s disease, or cystic fibrosis, you may not absorb enough vitamin K from your gut.

  • Weight-loss surgery – If you have had bariatric (weight-loss) surgery, you have a higher risk of vitamin K deficiency.

  • Antibiotics – Antibiotics may kill good bacteria in your gut that produce vitamin K. If you are taking antibiotics for long periods, you are at greater risk for a deficiency.

  • Cholesterol-lowering medicines – Certain cholesterol medicines, such as cholestyramine and colestipol, can lower how well you absorb fat-soluble vitamins, such as vitamin K (13).

  • Warfarin – Vitamin K can interact with the blood thinner, warfarin. You don’t have to cut vitamin K from your diet if you take warfarin, but you should make sure to get about the same amount of vitamin K every day, whether from foods or a supplement.

Signs or symptoms of deficiency

There are few signs or symptoms of vitamin K deficiency or insufficiency.

You usually won’t know if you have weak bones until you start breaking them.

And you won’t know if you have a buildup of calcium in your blood vessels until you have a heart attack or start having problems with your circulation.

One possible sign of a vitamin K deficiency is that your wounds won’t clot quickly and continue to bleed.

Another sign is that you bruise easily, which is actually bleeding under the skin.

Your doctor may order a prothrombin time (PT) test to check your body’s ability to clot blood.

Should You Take Vitamin K with Vitamin D

Many vitamins and other nutrients don’t work alone in your body and depend on each other.

Having a good intake of vitamin D and calcium can be dangerous if you don’t also get enough vitamin K.

Vitamin K helps get calcium into the bones.

If you are low in vitamin K, the calcium gets into your arteries instead of your bones, which contributes to heart disease. This leads to weak bones and hardened arteries.

If you and your doctor decide that you need to take a vitamin D supplement, make sure it also contains vitamin K2.

Ways to Get Vitamin K

  • Your gut – Bacteria in your gut make some vitamin K.

  • Diet – Vitamin K is found naturally in many foods.

    Vitamin K1 is found in green leafy vegetables (spinach, kale, lettuce), broccoli, blueberries, and some vegetable oils.

    Vitamin K2 is found in natto (a traditional Japanese food made from fermented soybeans), meat, cheese, egg yolks, and sauerkraut.

    There is no recommended dietary allowance (RDA) for vitamin K, but the adequate intake (AI) for adults is 120 mcg/day for men and 90 mcg/day for women (14).

  • Supplements – If you are not getting enough vitamin K from your diet or you have risk factors for vitamin K deficiency, talk to your doctor about a supplement.

    Look for a supplement with the MK-7 type of vitamin K2.

    If you are taking a vitamin D supplement, make sure it also contains vitamin K2 to protect your blood vessels.

Because vitamin K is fat-soluble, your supplement should be taken with a meal or snack that has some fat.

The fat in the food will help your body absorb the vitamin.

Supplements are not regulated by the Food and Drug Administration (FDA), so make sure you are buying high-quality supplements from a reputable source.

Avoid buying supplements made outside of the U.S., which may not be regulated at all.