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Vitamin K Deficiency: Causes, Symptoms & Health Risks

The information provided herein does not constitute an expert or medical advice, nor intended to replace such advice.

Health and Wellness

Micronutrients, including vitamins and minerals, are important for maintaining your health. In general, vitamins can’t be made inside your body, and have to be obtained through foods or supplements.

Vitamin K is important in a variety of processes throughout the body. How do you know whether you’re getting enough vitamin K? What causes vitamin K deficiency, and what are the signs of vitamin K deficiency?

Vitamin K deficiency symptoms

Vitamin K’s main action in the body is to help with blood clotting.  If you have low vitamin K levels, symptoms are primarily related to blood clotting. 

People who don’t have enough vitamin K may bleed and bruise easily. It may be difficult to stop the bleeding from even a minor cut. This can even lead to a hemorrhage, or a severe loss of blood.

Vitamin K deficiency diseases list

Besides blood clotting, vitamin K has actions in the bones and blood vessels. Because of this, lack of vitamin K symptoms may include effects on these structures.

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Some studies have linked low levels of vitamin K to an increased risk of fractures due to osteoporosis. However, studies of supplementation with vitamin K have not consistently shown that taking vitamin K reduces the risk of fractures. This issue is still controversial, but some experts advocate ensuring that you get enough vitamin K to protect your bones.

In addition, vitamin K may be linked to the risk of heart disease. It appears to help prevent calcium from depositing in the walls of arteries. Calcium deposition makes arteries stiff, which increases the risk of a heart attack or stroke. Supplementing with a specific form of vitamin K known as vitamin K2 has shown promising results in some studies for reducing the risk of heart attacks.  

Lack of vitamin K causes

Deficiency of vitamin K can potentially be caused by not eating enough of this vitamin, but this is very rare. In the US, most people’s diet contains enough vitamin K. 

If your body can’t absorb enough vitamin K, then this can lead to a deficiency. This may happen after bariatric surgery, which shortens the bowel to reduce absorption of calories and lead to weight loss. It can also happen with certain diseases that affect absorption in the intestines, such as celiac disease and ulcerative colitis.

Newborns often have low vitamin K levels, because this vitamin doesn’t easily cross the placenta to enter the baby’s blood. This can lead to bleeding in newborns. To prevent this issue, it’s standard medical practice to give newborns a single injection of vitamin K at birth.

Vitamin K daily dose

For adults, the recommended daily dose of vitamin K differs for men and women. This is because men have a larger average body size. The recommended daily dose is:

  • 90mcg for women

  • 120mcg for men

Vitamin K food sources

The best dietary sources of vitamin K are green leafy vegetables, such as spinach, kale, collard greens, chard, Brussels sprouts, cabbage, and lettuce. Broccoli also contains a lot of vitamin K. Soybeans are also high in this vitamin, especially natto (made from fermented soybeans). Meats and cheeses also have it at lower levels.

Vitamin K is fat-soluble, so the absorption in your digestive tract is best if you have your vitamin K with a little fat. For example, if you’re getting your vitamin K from leafy greens, you could drizzle some olive oil over them. This will help your body to absorb the vitamin K.

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Vitamin K toxicity

If you’re concerned that you might be deficient in vitamin K, then you might consider taking a supplement. With any supplement, it’s important to know whether there are any risks. Some vitamins and minerals can cause side effects if you take too much.

Fortunately, vitamin K toxicity is very rare. Although you shouldn’t take excessive doses, it’s also not considered to be particularly dangerous to take a vitamin K supplement.

Vitamin K and warfarin interaction

However, it’s important to be careful with vitamin K if you’re taking warfarin. This is a medication that’s given to people who are at risk for blood clots. It works by inhibiting the activation of vitamin K. This causes a decrease in the amount of clotting factors that the body can synthesize, which makes you less likely to get a blood clot.

If you’re taking warfarin, it’s important to keep your intake of vitamin K as consistent as possible. Higher levels of vitamin K require higher amounts of warfarin, while lower levels require lower amounts. If your vitamin K intake is always changing, then the dose of the medication may sometimes be too high and sometimes too low. This can lead to excessive bleeding at some times, and the potential for clots at other times. Try to keep your intake of vitamin K-rich foods as consistent as you can.

Vitamin K deficiency health risks

If you’re concerned about vitamin deficiencies in your diet, you could consider micronutrient testing. This will usually not be paid for by insurance, because it’s not considered to be cost effective to test everyone. However, you can order your own test kit and have it delivered to your home. You then take a blood sample by fingerprick, and send it back to the lab for testing.


Hariri E, Kassis N, et al. Vitamin K2-a neglected player in cardiovascular health: a narrative review. Open Heart. 2021 Nov;8(2):e001715. doi: 10.1136/openhrt-2021-001715.

Fusaro M, Cianciolo G, et al. Vitamin K and Osteoporosis. Nutrients. 2020 Dec; 12(12): 3625. doi: 10.3390/nu12123625

Warfarin. National Library of Medicine. https://ncbi.nlm.nih.gov/books/NBK470313/. Accessed 31 Jan 2023.

Vitamin K: Fact Sheet for Health Professionals. National Institutes of Health. https://ods.od.nih.gov/factsheets/VitaminK-HealthProfessional/. Accessed 31 Jan 2023.

Vitamin K Deficiency. National Library of Medicine. https://www.ncbi.nlm.nih.gov/books/NBK536983/. Accessed 31 Jan 2023.

Dr. Patricia Shelton

Dr. Patricia Shelton

Feb 06, 2023

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