Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate. The effectiveness ratings for VITAMIN K are as follows:
- Bleeding problems in newborns with low levels of vitamin K (hemorrhagic disease). Giving vitamin K1 by mouth or as a shot into the muscle helps prevent bleeding problems in newborns. Shots seem to work the best.
- Low levels of the blood clotting protein prothrombin (hypoprothrombinemia). Taking vitamin K1 by mouth or as an injection into the vein can prevent and treat bleeding problems in people with low levels of prothrombin due to using certain medications.
- A rare inherited bleeding disorder (vitamin K-dependent clotting factors deficiency or VKCFD). Taking vitamin K by mouth or as an injection into the vein can help prevent bleeding in people with VKCFD.
- Reversing the blood-thinning effects of warfarin. Taking vitamin K1 by mouth or as in injection into the vein can reverse too much blood thinning caused by warfarin. However, injecting vitamin K1 under the skin does not seem to work. Taking vitamin K along with warfarin also seems to help stabilize blood clotting time in people taking warfarin. It works best in people who have low vitamin K levels.
Possibly effective for…
- Weak and brittle bones (osteoporosis). Taking a specific form of vitamin K2 seems to improve bone strength and reduce the risk of fracture in most older women with weak bones. But it doesn’t seem to benefit older women who still have strong bones. Taking vitamin K1 seems to increase bone strength and might prevent fractures in older women. But it might not work as well in older men. Vitamin K1 doesn’t seem to improve bone strength in women who have not gone through menopause or in people with Crohn disease.
Possibly ineffective for…
- Bleeding into or around the fluid-filled areas (ventricles) of the brain (intraventricular hemorrhage). Giving vitamin K to women at risk for very preterm births does not seem to prevent bleeding in the brain of preterm infants. It also doesn’t seem to reduce the risk of nerve injury caused by these bleeds.
Insufficient evidence to rate effectiveness for…
- Athletic performance. Early research suggests that taking vitamin K2 by mouth might improve exercise performance by increasing the work of the heart.
- A blood disorder that reduces levels of protein in the blood called hemoglobin (beta-thalassemia). Early research shows that taking vitamin K2 by mouth along with calcium and vitamin D can improve bone mass in children with this blood disorder.
- Cystic fibrosis. People with cystic fibrosis can have low levels of vitamin K due to problems digesting fat. Taking a combination of vitamins A, D, E, and K seem to improve vitamin K levels in people with cystic fibrosis who have trouble digesting fat. But there is no reliable evidence suggesting that vitamin K improves overall health in people with cystic fibrosis.
- Diabetes. Early research shows that taking a multivitamin fortified with vitamin K1 does not lower the risk of developing diabetes compared to taking a regular multivitamin.
- Acne-like rash caused by certain cancer drugs. People who are given a certain type of anticancer medicine often develop a skin rash. Early research shows that applying a cream containing vitamin K1 helps prevent skin rash in people being given this type of medicine.
- High cholesterol. There is early evidence that vitamin K2 might lower cholesterol in people on dialysis with high cholesterol levels.
- Liver cancer. Taking vitamin K2 does not seem to prevent liver cancer recurrence. But some early research shows that taking vitamin K2 reduces the risk of liver cancer in people with liver cirrhosis.
- Multiple sclerosis (MS). Interferon is a medicine that helps people with MS. This medicine often causes a rash and burning of the skin. Early research shows that applying vitamin K cream modestly reduces rash and burning in people treated with interferon.
- Rheumatoid arthritis (RA). Early research shows that taking vitamin K2 along with arthritis medicine reduces markers of joint swelling better than taking arthritis medicine alone. But taking vitamin K1 does not seem to reduce symptoms of RA.
- Spider veins.
- Stretch marks.
- Other conditions.
More evidence is needed to rate vitamin K for these uses.
Side Effects Of Vitamin K
- When taken by mouth: The two forms of vitamin K (vitamin K1 and vitamin K2) are LIKELY SAFE for most people when taken appropriately. Most people do not experience any side effects when taking vitamin K in the recommended amount each day. However, some people may have an upset stomach or diarrhea.
- When applied to the skin: Vitamin K1 is POSSIBLY SAFE for most people when applied as a cream that contains 0.1% vitamin K1.
- When given by IV: The two forms of vitamin K (vitamin K1 and vitamin K2) are LIKELY SAFE for most people when injected into the vein appropriately.
Warnings & Precautions
- Pregnancy and breast-feeding: When taken in the recommended amount each day, vitamin K is LIKELY SAFE for pregnant and breastfeeding women. Don’t use higher amounts without the advice of your healthcare professional.
- Children: The form of vitamin K known as vitamin K1 is LIKELY SAFE for children when taken by mouth or injected into the body appropriately.
- Diabetes: The form of vitamin K known as vitamin K1 might lower blood sugar levels. If you have diabetes and take vitamin K1, monitor your blood sugar levels closely.
- Kidney disease: Too much vitamin K can be harmful if you are receiving dialysis treatments due to kidney disease.
- Liver disease: Vitamin K is not effective for treating clotting problems caused by severe liver disease. In fact, high doses of vitamin K can make clotting problems worse in these people.
- Reduced bile secretion: People with decreased bile secretion who are taking vitamin K might need to take supplemental bile salts along with vitamin K to ensure vitamin K absorption.
Vitamin K Dosage
The following doses have been studied in scientific research:
- For weak and brittle bones (osteoporosis): The MK-4 form of vitamin K2 has been taken in doses of 45 mg daily. Also, vitamin K1 has been taken in doses of 1-10 mg daily.
- For a rare, inherited bleeding disorder (vitamin K-dependent clotting factors deficiency or VKCFD): 10 mg of vitamin K has been taken 2-3 times weekly.
- For reversing the blood-thinning effects of warfarin: A single dose of 1-5 mg of vitamin K1 is typically used to reverse the effects of taking too much warfarin. The exact dose needed is determined by a lab test called the INR. Daily doses of 100-200 micrograms of vitamin K have been used for people taking warfarin long-term who have unstable blood clotting.
WITH A NEEDLE:
- For a rare, inherited bleeding disorder (vitamin K-dependent clotting factors deficiency or VKCFD): 10 mg of vitamin K has been injected into the vein. How often these injections are given is determined by a lab test called the INR.
- For reversing the blood-thinning effects of warfarin: A single dose of 0.5-3 mg of vitamin K1 is typically used. The exact dose needed is determined by a lab test called the INR.
- For bleeding problems in newborns with low levels of vitamin K (hemorrhagic disease): 1-2 mg of vitamin K1 has been given in three doses over 8 weeks. Also single doses containing 1 mg of vitamin K1, 5 mg of vitamin K2, or 1-2 mg of vitamin K3 have been used.
WITH A NEEDLE:
- For bleeding problems in newborns with low levels of vitamin K (hemorrhagic disease): 1 mg of vitamin K1 has been given as a shot into the muscle.
- There isn’t enough scientific information to determine recommended dietary allowances (RDAs) for vitamin K, so daily adequate intake (AI) recommendations are used instead: The AIs are: infants 0-6 months, 2 mcg; infants 7-12 months, 2.5 mcg; children 1-3 years, 30 mcg; children 4-8 years, 55 mcg; children 9-13 years, 60 mcg; adolescents 14-18 years (including those who are pregnant or breast-feeding), 75 mcg; men over 19 years, 120 mcg; women over 19 years (including those who are pregnant and breastfeeding), 90 mcg.
Consult your doctor or pharmacist.
All information has been provided courtesy of MedLinePlus from the National Library of Medicine and from the FDA.