Vitamin K is a fat-soluble vitamin. It gets its name from the German word for clotting, which is "koagulation."[1] There is a group of K vitamins, but the only one used in the United States is K1 (phytonadione). Other forms of vitamin K are not considered as safe or effective.[1]
Uses
Vitamin K is primarily used as a coagulant to aid blood clotting. It is often administered to counteract the undesirable effects of blood-thinning medications. Also, it's used as a supplement in newborns lacking adequate amounts of the vitamin to prevent clotting problems.[1, 2]
Other uses
Vitamin K is also used for:
- Deficiency prevention and treatment
- Osteoporosis
- Itching (for those with biliary cirrhosis, a liver disease)
- Burns
- Scar removal
- Spider veins
- Rosacea (skin condition that causes facial redness and pimples)
- Bruise prevention
- Skin healing
Dosage
Blood tests are used to set the proper dosage of vitamin K. The tests, which determined how long it takes for blood to clot, are known as the International Normalized Ratio (INR) and Prothrombin Time (PT) tests. Generally, 2.5mg to 25mg are prescribed for bleeding disorders, while 1mg to 5mg is the preferred dose to counteract bleeding due to taking too much anticoagulant.[2]
Does vitamin K work
According to research, vitamin K seems to be effective for treating and preventing deficiency of the vitamin as well as for preventing blood clots. There isn't enough evidence for its use to treat other conditions, such as heart disease, brittle bones and swelling.
Interactions
Do not mix vitamin K with warfarin (Coumadin), which is a blood thinner. The vitamin may reduce the effectiveness of the drug. As for other interactions, do not take vitamin K with:[1, 2]
| Drug/Supplement | Interaction |
|---|---|
| Vitamin A | Interferes with vitamin K's ability to aid clotting in animals. The effect on people isn't known. |
| Vitamin E | Taking more than 800 units daily can adversely affect vitamin K's clotting ability. It also can increase the chance of bleeding in those who are on Warfarin or who don't get a lot of vitamin K in their diet. Avoid high doses. |
| Tiratricol | It interferes with vitamin K's clotting ability. |
| Coenzyme-Q10 (CoQ10) | Also a clotting aid, taking them at the same time can increase the intensity of their effects. |
| Antibiotics | These may lower the amount of vitamin K in the body or make it less effective. |
If you're taking any medication, consult your healthcare provider before taking vitamin K.
Safety
- It's generally safe to take vitamin K in recommended doses, even if you are breastfeeding or pregnant.[1]
- Don't alter vitamin K intake when taking blood thinners. Keep it consistent daily.[2]
- Do not use too much vitamin K if you're on dialysis for kidney disease.[1]
- If you have clotting issues related to severe liver disease, excessive amounts of vitamin K could worsen the problem.[1]
Vitamin K sources
Examples of foods containing vitamin K are:
- Green leafy vegetables -- spinach, kale, Swiss chard
- Brussels sprouts
- Broccoli
- Cabbage
- Avocado
- Raw berries (black and blue)
- Peas
- Tuna (canned in oil)
Forms
The vitamin is also available in tablet, capsule, and liquid form, as part of a multivitamin or by itself. Vitamin K can be injected for patients with clotting disorders.
References
- MedlinePlus; "Vitamin K;" Reviewed 2012
- National Institutes of Health Clinical Center, Drug-Nutrient Interaction Task Force; "Important Information to Know When You Are Taking: Warfarin (Coumadin) and Vitamin K;" September 2012
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Vitamin K Price Alerts
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