What Is a Vitamin K Deficiency?

The fat-soluble vitamin K helps blood clot and maintains bone health. A deficiency in the nutrient could lead to significant bleeding and osteoporosis. A vitamin K deficiency is uncommon in healthy adults because most get it from green vegetables and bacteria in the intestine. However, newborns are at risk and may receive a vitamin K injection at birth. Sources of vitamin K include dark leafy greens and fermented plant foods.

Read on to learn what vitamin K is, its role in the body, and the signs and symptoms of a deficiency. This article also explains what foods can increase levels of vitamin K.

The “K” comes from the German word “Koagulation,” meaning to clot blood and prevent hemorrhage.

The nutrient is part of a group of fat-soluble vitamins, including:

• Vitamin K1, phylloquinone: Aids in blood clotting.
• Vitamin K2, menaquinone-4 (MK-4), and vitamin K2, menaquinone-7 (MK-7): Your body synthesizes these vitamins and more in your bone, cartilage, and blood vessel walls. Vitamin K2 helps transport calcium, preventing calcium deposits from building up in the lining of blood vessel walls and helping improve bone density.
• Vitamin K3, menadione: Vitamin K3 is a potentially toxic manufactured form of vitamin K. Researchers are studying vitamin K3 to find out whether it can help with prostate and hepatocellular cancer therapy and some skin disorders.

According to the National Institute of Health (NIH), the table below shows how much vitamin K is required daily in micrograms (mcg) to ensure nutritional adequacy or adequate intake (AI), depending on age and sex.

Research shows that your body needs vitamin K to produce proteins that help blood clot and maintain calcium levels.

Adequate levels of vitamin K may contribute to improved cognition in older adults.  

Your body uses vitamin K in proteins that may help lower calcification. Vascular calcification is an active process that can cause cardiovascular disease.

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Some studies link vitamin K intake to contributing to a higher bone mineral density and lower hip fracture incidence.

One study of Japanese patients suggested that those who increased their levels of vitamin K2 by eating fermented soybeans had fewer hip and vertebra fractures. Other studies, however, did not show an improvement in bone density.

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Research suggests that insufficient levels of vitamin K may lead to mineral deposits in your cartilage and bones. These deposits may contribute to the symptoms of osteoarthritis.

Evidence suggests that supplementing vitamin K2 may reduce inflammation resulting from arthritis.

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Vitamin K helps your body produce proteins that play a role in the peripheral and central nervous systems. So increased levels of vitamin K may improve cognitive function in healthy older adults.

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One study showed that taking a vitamin K supplement of 10 mcg a day reduces the risk of developing diabetes by 7%.

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Sources of vitamin K include green vegetables and fruits. K1 is predominately found in green vegetables and plant chlorophyll.

Sources of vitamin K1 include:

• leafy greens
• asparagus
• Brussels sprouts
• grapes
• kiwi
• avocado

Sources of vitamin K1 include:

Bacteria in your gut synthesize vitamin K2. The top sources of vitamin K are those in which bacteria are part of the production process of food.

• nattō, which is fermented soy
• sauerkraut
• dairy products, especially hard cheeses

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The most typical sign of a vitamin K deficiency is usually bleeding, but other signs may occur, such as:

• bruising easily
• gastrointestinal hemorrhage
• hemorrhagic disease of the newborn

A vitamin K deficiency is uncommon in healthy adults but can occur in newborns. Vitamin K transport across the placenta is usually weak, increasing the risk of a deficiency in newborn babies.

People with malabsorption syndromes and other gastrointestinal disorders, such as cystic fibrosis, celiac disease, ulcerative colitis, and short bowel syndrome, may not absorb sufficient vitamin K.

Antibiotics can destroy vitamin K-producing bacteria in the gut. You can potentially develop a vitamin K deficiency if you also have a low vitamin K intake.

This is more likely with cephalosporin antibiotics, such as Cefobid. These antibiotics might also inhibit the action of vitamin K in the body.

You can treat a vitamin K deficiency by increasing your intake through diet or supplementation.

A vitamin K deficiency may cause complications in newborn babies, as it does not cross over from the placenta well. During the first few weeks of life, vitamin K deficiency can lead to vitamin K deficiency bleeding (VKDB).

This is associated with bleeding in the umbilicus, gastrointestinal tract, skin, nose, and other areas. To prevent VKDB, the American Academy of Pediatrics recommends administering a single intramuscular dose of 0.5 to 1 milligram (mg) of vitamin K1 at birth.

Current research does not show that high doses of oral vitamin K1 or vitamin K2 are harmful. However, there is evidence that IV administration of vitamins can contribute to bronchospasm and cardiac arrest.

Certain medications can interfere or interact with vitamin K. These can include:

• anticoagulants such as warfarin
• antibiotics
• bile acid sequestrants, which reduce cholesterol levels
• orlistat, a weight loss drug

Vitamin K contributes to blood clotting and maintains bone health. A vitamin K deficiency is uncommon in adults but can occur in newborns.

You can help maintain your levels of vitamin K by including green leafy vegetables, fruits, nuts, fermented foods, meats, and cheeses in your diet.