Vitamin K | Health Notes at WWSM | Health Information at WWSM

Vitamin K

Also indexed as: Phylloquinone, Phytonadione

Vitamin K is needed for proper bone formation and blood clotting. In both cases, vitamin K does this by helping the body transport calcium. Vitamin K is used by doctors when treating an overdose of the drug warfarin. Also, doctors prescribe vitamin K to prevent excessive bleeding in people taking warfarin but requiring surgery.

Where is it found?

Leafy green vegetables, such as spinach, kale, collards, and broccoli, are the best sources of vitamin K. The greener the plant, the higher the vitamin K content.¹ Other significant dietary sources of vitamin K include soybean oil, olive oil, cottonseed oil, and rape seed oil.²

Vitamin K has been used in connection with the following conditions (refer to the individual health concern for complete information):

Science Ratings	Health Concerns
	Coeliac disease (for deficiency only) Crohn’s disease Cystic fibrosis Osteoporosis
	Acute myeloid leukaemia (vitamin K2 only) Morning sickness Myelodysplastic syndromes (vitamin K2 only) Phenylketonuria (if deficient)
Reliable and relatively consistent scientific data showing a substantial health benefit. Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit. For a herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support and/or minimal health benefit.

Science Ratings

Health Concerns

Coeliac disease (for deficiency only)

Crohn’s disease

Cystic fibrosis

Osteoporosis

Acute myeloid leukaemia (vitamin K2 only)

Morning sickness

Myelodysplastic syndromes (vitamin K2 only)

Phenylketonuria (if deficient)

Reliable and relatively consistent scientific data showing a substantial health benefit.
2Stars

Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.
1Star

For a herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support and/or minimal health benefit.

Who is likely to be deficient?

A vitamin K deficiency, which causes uncontrolled bleeding, is rare, except in people with certain malabsorption diseases. However, there are reports of severe vitamin K deficiency developing in hospitalised patients who had poor food intake and were receiving antibiotics.³ All newborn babies receive vitamin K to prevent deficiencies that sometimes develop in breast-fed babies.

How much is usually taken?

The recommended dietary allowance for vitamin K is about 1 mcg per 2.2 pounds of body weight per day or about 65 to 80 mcg per day for most adults.⁴ This level of intake may be achieved by consuming adequate amounts of leafy green vegetables. However, studies have shown that many men and women aged 18 to 44 years ingest less than the recommended amount of vitamin K.⁵ ⁶

Are there any side effects or interactions?

Allergic reactions to vitamin K injections have been reported on rare occasions.⁷

Vitamin K facilitates the effects of calcium in building bone and proper blood clotting.

Are there any drug interactions?
Certain medicines may interact with vitamin K. Refer to drug interactions for a list of those medicines.

References
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The information presented in Healthnotes is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or chemist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires September 2008.

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Where is it found?

Who is likely to be deficient?

How much is usually taken?

Are there any side effects or interactions?