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Vitamin K

(phylloquinones, menaquinones)

Vitamin K is a fat-soluble vitamin that is stored in the fatty tissue of the body. Vitamin K is not a single vitamin but is a family of compounds including K1, K2 and K3. Vitamin K1 or phylloquinones is made by plants; vitamin K2 or menaquinones is derived from bacteria in our gastrointestinal tract. For this reason, deficiency of this vitamin is not common. Vitamin K3 or menadione is the only form which does not occur naturally in the body.

Vitamin K is best known for it's role in healthy blood clotting. In fact, vitamin K is the shortened version of the German word koagulation to describe this vitamin’s key function. Proper blood clotting ensures that you stop bleeding when you have a cut from injury, surgery, etc.

More recent studies indicate the importance of this vitamin to bone health as it is responsible for converting a bone protein (osteocalcin) from its inactive to active form. Vitamin K also ensures that the process of bone demineralization (minerals are taken out of the bones by osteoclasts) is kept in check. The Nurses Health Study, involving over 72,000 women, showed that post-menopausal women who got the most vitamin K had the lowest incidence of hip fracture.

Vitamin K has been also found to prevent calcification or the build-up of calcium (hardening) in the arteries, which can lead to arteriosclerosis (a build-up that occurs in the middle of the artery; as opposed to atherosclerosis - a build up that occurs on the inside of the artery and is visible). Note, arteriosclerosis is associated with aging and has nothing to do with cholesterol; it has to do with calcification. Vitamin K helps prevent the build up of calcium in the arteries. Individuals with vitamin K deficiency are at greater risk of developing hardening of the arteries.

Vitamin K is a common ingredient found in topical anti-bruising products. Studies have demonstrated that vitamin K applied topically after laser treatment reduces the severity of bruising particularly in the initial days of application. Vitamin K also hastens the resolution of the laser-induced purpura (bruising). Topical vitamin K is also used to diminish broken capillaries, to treat rosacea, aid in fading of hyperpigmentation (hydroquinone) and reduce dark circles under the eyes.

Major Functions of Vitamin K

- Necessary for proper blood clotting

- Essential for bone formation and repair

- Prevents calcification of your arteries

- Resolves bruising more rapidly

- Inhibits a biochemical messenger for the immune system that promotes inflammation

Food Sources

Dark green leafy vegetables - kale, spinach, turnip greens, collards, Swiss chard, parsley, mustard greens; Brussels sprouts, green leaf lettuce, broccoli, endive, romaine lettuce, iceberg lettuce, red cabbage, asparagus, cabbage, cauliflower, liver, oatmeal and soybeans. Fruits like avocado and kiwi. Products derived from bacterial fermentation (e.g., fermented soybeans and cheese) and vegetable oils.

Unlike many other vitamins, freezing, storing and cooking does not reduce the amount of vitamin K in foods. However, commercial production of fruit and vegetable juices does reduce the vitamin K content of these foods.

Recommended Dietary Allowance

The Recommended Dietary Allowance (RDA) for vitamin K for adult men is 120 mcg and for adult women is 90 mcg. A Tolerable Upper Intake Level for vitamin K has not been determined due to lack of data due to adverse events.

If you look on a nutritional supplement facts panel, you'll notice the Amount Per Serving for vitamin K and the % Daily Values is at located at the top of the panel. The Amount Per Serving is based on the Reference Daily Intake (RDI) for this nutrient which is considered to be sufficient to meet the requirements of nearly all (97–98%) healthy individuals in each life-stage and sex group. The Reference Daily Intake for vitamin K is 80 mcgs which represents 100% of the Daily Values. Keep in mind, that the Daily Values is the amount considered sufficient to promote proper blood clotting function. Research indicates that higher amounts are needed to enhance bone and cardiovascular health.


Vitamin K interacts with anticoagulant drugs like Coumadin® (warfarin). This medication is prescribed for people who are at increased risk of forming blood clots. For Coumadin to work effectively, it is important to keep vitamin K intake consistent as sudden increases may decrease the effect of the medication.

Long term use of medications like Coumadin and antibiotics may result in a deficiency of vitamin K. Antibiotics interfere with the normal microbiota and therefore could interfere with the production of vitamin K in the gut. Higher intakes of vitamin E (above 600 IUs daily), could also interfere with vitamin K function.

If you’re taking supplements like ginkgo, garlic or ginger to prevent blood clots (coagulation) and increase blood flow, vitamin K won’t interfere with their effect. Vitamin K works by preventing platelet aggregation a process that is different from coagulation.

VitaMedica Products

Although many patients could benefit from taking vitamin K during the peri-operative period, the supplements in VitaMedica’s Recovery Product line are not formulated with this vitamin. This allows our Recovery programs to be taken by patients who normally take Coumadin. However, our Arnica+K Cream is formulated with vitamin K and is intended to help resolve bruises more rapidly.

A number of the multi-nutrient products in our Wellness Product line are formulated with vitamin K. Vitamin K along with other bone supporting nutrients is included in our Bone Support formulation (75 mcg). Anti-Aging Formula features this nutrient (50 mcg and 25 mcg, respectively).

Last updated September 18, 2018

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