What is vitamin K?

Kathleen Dunn
Nutrition & Dietetics
Many people recognize vitamin K as the “blood-clotting vitamin.” In your body, it acts as a coenzyme, a sort of biochemical spark plug, that activates key proteins involved in the normal clotting of blood. But this fat-soluble vitamin also activates several proteins that help build and maintain strong bones. That's why you’ll often find it in high-quality supplements for bone health.

A little goes a long way - Although your healthy gut flora can make some vitamin K, you need to consume a minimum amount in your daily diet to meet your body’s basic needs. Vitamin K is measured in micrograms. For adults and children over 4 years of age, 100% of the Daily Value is 80 micrograms per day.

Fill your plate with greens - If your daily menu includes plenty of greens, you’re likely consuming an adequate intake of vitamin K. In fact, certain vegetables are packed with 100% or more of the Daily Value in each one-half cup serving (cooked). These high-potency options include kale, spinach, collard greens, beet greens, broccoli, Brussels sprouts and cabbage.

Add a daily supplement - If greens aren’t making a regular appearance at your meals, consider adding a high-quality multivitamin or bone health supplement with vitamin K to your daily routine. It helps fill any nutrient gaps that may occur between what your typical diet provides and what your body really needs.

As with all dietary supplements, talk to your doctor or other licensed healthcare professional prior to use if you have or suspect a medical condition, if you are taking over-the-counter or prescription drugs or if you are pregnant or lactating.
Harris H. McIlwain, MD
Vitamin K is a vitamin that has a vital role in calcium absorption. It has an indirect role in preventing bone loss with osteoporosis.  
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Vitamin K helps the blood to clot or coagulate and is instrumental in bone health. It is classified as a fat-soluble vitamin because it is found in the body's fat tissue and liver. Vitamin K is found in broccoli, turnip greens, spinach, kale, asparagus, cabbage, green tea, beef liver and lettuce. It is also produced by intestinal bacteria. This is why it is very rare to have a vitamin K deficiency. If you do have a vitamin K deficiency, there are many supplements that can provide extra vitamin K. These medications are available by prescription or over-the-counter and go by different names like Mephyton Tablets, Menadione, Vitamin K Tablets, Menaphthone, Vitamin K1 Tablets, Menaquinone, Vitamin K2, Phylloquinone and Vitamin K3. Vitamin K is available in tablet, capsule, injection and liquid forms.
There are two forms of vitamin K: menaquinone and phylloquinone. Menaquinone is synthesized by the bacteria that exist naturally in your intestinal tract. Phylloquinone is found in green plants, and is the primary source of vitamin K in your diet.

An easy way to remember vitamin K’s major function is to associate the letter with “klotting.”

Vitamin K plays a major role in blood coagulation, or clotting. Blood clotting is a complex chain of events involving substances in your blood, many of which are proteins, called clotting factors. Vitamin K plays a role in synthesizing four of these clotting factors.

Without vitamin K, a simple cut on your finger would cause uncontrollable bleeding.

Green leafy vegetables are a good source of vitamin K.
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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.