vitamin K

Also indexed as
Phylloquinone, Phytonadione
Introduction
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 canola 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
** - Celiac disease (for deficiency only)
** - Crohn’s disease
** - Cystic fibrosis
** - Osteoporosis
* - Acute myeloid leukemia (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 an 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 hospitalized patients who had poor food intake and were receiving antibiotics.3 All newborn infants receive vitamin K to prevent deficiencies that sometimes develop in breast-fed infants.
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.
Drug Interactions
Certain medicines interact with vitamin K: Some interactions may increase the need for vitamin K (+), other interactions may be negative (-) and indicate vitamin K should not be taken without first speaking with your physician or pharmacist, others may require further explanation (?). Refer to the individual drug article for specific details about an interaction.
Note: The following list only includes the generic or class name of a medicine. To find a specific brand name, use the Medicines index.
Aminoglycoside Antibiotics (+)
Amoxicillan–Potassium Clavulanate (+)
Amoxicillin (+)
Ampicillin (+)
Antibiotics (+)
Anticonvulsants (+)
Azithromycin (+)
Bile Acid Sequestrants (+)
Cephalosporins (+)
Chlorhexidine (+)
Ciprofloxacin (+)
Clarithromycin (+)
Clindamycin Oral (+)
Clindamycin Topical (+)
Colestipol (+)
Cycloserine (+)
Dapsone (+)
Dicloxacillin (+)
Doxycycline (+)
Erythromycin (+)
Gabapentin (+)
Gentamicin (+)
Isoniazid (+)
Levofloxacin (+)
Loracarbef (+)
Macrolides (+)
Mineral Oil (+)
Minocycline (+)
Neomycin (+)
Nitrofurantoin (+)
Ofloxacin (?)
Oral Corticosteroids (?)
Penicillin V (+)
Penicillins (+)
Phenobarbital (+)
Quinolones (+)
Sulfamethoxazole (+)
Sulfasalazine (+)
Sulfonamides (+)
Tetracycline (+)
Tetracyclines (+)
Tobramycin (+)
Trimethoprim (+)
Trimethoprim/Sulfamethoxazole (+)
Valproic Acid (+)
Warfarin (?)