Vitamin K

Nonessential Micronutrient



Though it’s not often supplemented, Vitamin K is needed for proper blood clotting (coagulation) and bone formation. Cases of clinical deficiencies may reveal themselves by excessive nose bleeds or prolonged bruising.

Other names for Vitamin K

Vitamin K1, phylloquinone, phytonadione

Where to find Vitamin K

Most of our Vitamin K supply is created in our intestines by “good” bacteria. But it’s also found in dark green leafy vegetables, broccoli, Brussel’s sprouts, alfalfa, and kelp and in animal sources, such as liver, milk, yogurt, and egg yolks. The greatest amount is found in fat-soluble chlorophyll — the green pigment of plants.

Tip Taking acidophilus or eating foods that contain it, like yogurt, increases the natural production of Vitamin K by aiding the function of healthy bacteria in the intestines.

Popup: Foods highest in Vitamin K


Why athletes use Vitamin K

Although this vitamin is pretty accessible, in all actuality, the only time an athlete would supplement with Vitamin K, which is necessary to promote blood clotting and wound healing, by itself is when clinically found to be deficient and under a doctor’s care. Normal, healthy ranges of Vitamin K can be attained through diets consisting of plenty of greens and/or milk; it’s also commonly found in multivitamin blends.

Ways that Vitamin K can enhance Muscle Gain & Recovery:
Ways that Vitamin K can enhance Longevity:
  • Ensure normal blood clotting and proper healing of wounds
  • Promote healthy liver function by detoxifying the body


Signs of Vitamin K deficiency

Deficiency of Vitamin K has been linked to:

  • Inhibited blood clotting (coagulation)
  • Impaired healing of wounds
  • Excessive bleeding
  • Bone and joint problems
  • Bruising
Potential uses for Vitamin K

Research indicates that Vitamin K may also be useful in the treatment of:

  • Excessive bleeding
  • Nausea
  • Osteoporosis
  • Skin conditions, such as eczema or psoriasis
  • Morning sickness
  • Liver disorders
  • Gallbladder disease
  • Gastrointestinal disorders


More about Vitamin K

Vitamin K is necessary for proper blood clotting or coagulation, though many people are unaware of their needs for this fat-soluble vitamin. While Vitamin K is included in many multivitamins, it’s typically not supplemented alone unless a clinical deficiency has been diagnosed. Although deficiencies are quite uncommon, it certainly doesn’t hurt to know why K is so important.

What it does and why it’s important

Necessary for prothrombin formation, Vitamin K works with proteins to literally transform them into “clotting proteins,” which are necessary for our bodies to heal from cuts and wounds. If a deficiency condition exists, the body is more likely to excessively bleed, and it’s more difficult to recover from bruises.

K also helps direct calcium and potassium through our blood to our bones, helping support bone strength and formation, and even increase bone mass in people experiencing loss, most commonly due to age.

Because Vitamin K is produced in our intestinal tracts by “good” bacteria, it’s important to keep that bacteria healthy. One way to do that is by ingesting live cultures, such as acidophilus, which is found in yogurt. Another way to get adequate amounts of K is to consume plenty of leafy greens, including salads.

Deficiency signs and symptoms

While K deficiency is uncommon, it can occur due to prolonged antibiotic and blood thinner use, various absorption issues, low dietary intakes of K-containing foods, or liver disease. Such clinical deficiencies are treated by a doctor. Fortunately, most diets provide 70 to 150 mcg daily, with normal absorption between 20 and 60% of intake, which is adequate for most people.

Most notably, deficiencies can result in abnormal bleeding, such as excessive nosebleeds or prolonged bruises. Most commonly prescribed to prevent hemorrhaging, K is also given to infants who don’t have the necessary bacteria to synthesize it naturally for their first few days. Supplementing with alfalfa or chlorophyll can also increase K levels.

In conclusion

Vitamin K’s not normally required for those of us who eat our leafy greens (which provide about 75 mg per day). While we don’t usually need to supplement with this vitamin unless we begin to show symptoms of deficiency (which is rare), it can still be found in a number of multivitamin/mineral formulas. Keep in mind that if your body does start warning you of a deficiency, by bleeding excessively, bruising, etc., you should go for a friendly visit with your doctor because supplementing alone may not treat these symptoms, and the results of a deficiency can be serious.



A common recommendation for adults who are found to be clinically deficient in Vitamin K is 2 mcg per kilogram (2.2 lbs) of bodyweight per day. For example, if you weigh 180 lbs, you would need about 160 mcg daily.


Vitamin K should be taken with food in divided doses, though not with Vitamin E, as they compete against one another (Vitamin E being a blood thinner). Also, excess Vitamin A appears to interfere with Vitamin K absorption.


If you are deficient in Vitamin K, you should routinely be monitored by a physician to note the effects on blood clotting. If Vitamin K deficiency is suspected, it may be best to try to first obtain sufficient amounts found naturally in foods before resorting to supplementation.

Synergists of Vitamin K

Vitamin K taken with Vitamin C may reduce morning sickness.

Safety of Vitamin K

Vitamin K supplementation should be avoided during the last few weeks of pregnancy.

Drugs that interact with Vitamin K

Vitamin K consumption should be limited while using blood-thinning drugs such as coumadin or warfarin because it interferes with the actions of these prescription medications.

Toxicity of Vitamin K

None known at recommended amounts.

Bans and restrictions

None reported.


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  • Booth, S.L., et al., “Assessment of Phylloquinone and Dihydrophylloquinone Dietary Intakes Among a Nationally Representative Sample of US Consumers Using 14-Day Food Diaries,” J Am Diet Assoc 99.9 (1999) : 1072-6.
  • Booth, S.L., and Suttie, J.W., “Dietary Intake and Adequacy of Vitamin K,” J Nutr 128.5 (1998) : 785-8.
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  • von Kries, R., et al., “Vitamin K in Infancy,” Eur J Pediatr 147.2 (1988) : 106-12.
  • Vermeer, C., et al., “Role of Vitamin K in Bone Metabolism,” Annual Reviews of Nutrition, Volume 15 (1995) 1-22.