Vitamin K is a nutrient that is necessary for blood clotting. Found in a number of vegetables, vitamin K is also available in supplement form or as a cream. Additionally, vitamin K is produced by the bacteria lining your gastrointestinal tract.
Benefits of Vitamin K
Vitamin K is typically used to treat blood clotting problems and vitamin K deficiency. Vitamin K supplements are also purported to promote bone formation and protect against bone diseases like osteoporosis. In addition, some people take vitamin K to alleviate itching caused by biliary cirrhosis (a liver disease).
What Is Vitamin K Cream?
Vitamin K is widely available in creams said to treat various skin conditions. Proponents claim that applying vitamin K cream to the skin can remove varicose veins, dark circles under the eyes, bruises, scars, and stretch marks, as well as treat rosacea and speed up the healing of wounds and burns. In most cases, vitamin K creams also contain other natural substances (such as herbal extracts and plant oils).
Vitamin K and Coumadin
If you're taking Coumadin (warfarin), it's important to monitor your intake of vitamin K. (A blood-thinning medication often prescribed to prevent heart attacks and stroke, Coumadin keeps blood clots from forming or growing larger in your blood and blood vessels.) Since vitamin K plays a key role in blood clotting, it can decrease the effectiveness of Coumadin.
When too much Coumadin is given to a patient, vitamin K may reverse the potentially harmful effects of the drug. However, it's crucial for people taking Coumadin to increase their vitamin K intake only under the supervision of their health-care provider.
The Science Behind Vitamin K
There is not yet enough scientific evidence to support the use of vitamin K for any condition apart from vitamin K deficiency and certain bleeding or blood clotting problems, according to the National Institutes of Health (NIH).
However, some studies suggest that vitamin K shows promise for the prevention or treatment of other health problems. Here's a look at some key findings:
1) Vitamin K and Bone Health
Vitamin K may improve bone health, according to a 2001 research review published in Nutrition. Sizing up the available data on vitamin K and bone health, the review's authors found that vitamin K can increase bone mineral density and reduce fracture rates in people with osteoporosis. The authors note that vitamin K may be particularly effective when combined with vitamin D, a nutrient known to play a critical role in bone metabolism.
2) Vitamin K and Heart Disease
Preliminary findings from animal-based studies indicate that vitamin K may protect against atherosclerosis (hardening of the arteries). However, in a 2008 report from Current Opinion in Lipidology, scientists caution that human-based research on vitamin K1 and heart disease has yielded mixed results.
Foods High in Vitamin K
Leafy green vegetables are a top source of vitamin K. In fact, eating just one serving (i.e., a half-cup) of any of the following foods provides more than double your daily requirement for vitamin K:
- kale
- spinach
- turnip greens
- collard greens
- Swiss chard
- parsley
- mustard greens
Brussel sprouts, broccoli, and romaine lettuce are also rich in vitamin K.
Vitamin K1 vs. Vitamin K2
Vitamin K1 (also known as phylloquinone) is the natural form of vitamin K found in plants. However, phytonadione (the synthetic version of phylloquinone) is commonly referred to as "vitamin K1" on supplement labels. Vitamin K is also available in other forms, including vitamin K2 (menaquinone) and vitamin K3 (menaphthone or menadione).
According to the NIH, vitamin K1 is less toxic, faster-acting, stronger, and more effective for certain conditions than other forms of vitamin K. Still, some research suggests that intake of vitamin K2 may offer certain health benefits, such as increased protection against heart disease.
Currently, the U.S. Food and Drug Administration prohibits the sale of vitamin K3 in dietary supplements. Injectable vitamin K3 is sometimes used in medical treatments, but there's evidence that these injectable formulas may cause allergic reactions and toxic effects.
Vitamin K Deficiency
A very rare condition, vitamin K deficiency occurs when the body can't properly absorb vitamin K from the intestinal tract. This problem may be caused by certain diseases (including cystic fibrosis, celiac disease, and Crohn's disease), long-term use of antibiotics or blood-thinning medications, or treatment with hemodialysis. Signs and symptoms of vitamin K deficiency include excessive bleeding and bruising.
Is Vitamin K Safe?
Vitamin K is considered safe for most people. However, taking high amounts of vitamin K may be harmful to pregnant and breastfeeding women, patients receiving dialysis treatments due to kidney disease, and people with clotting problems caused by severe liver disease. In addition, vitamin K may interact with certain supplements (including coenzyme Q10, vitamin E).
Should You Use Vitamin K for Health Purposes?
While vitamin K may help with certain health problems, self-treating a chronic condition with vitamin K and avoiding standard care may have serious health consequences. Before you begin using vitamin K, talk to your doctor to determine a safe and effective dosage.
Sources
American Cancer Society. "Vitamin K". October 2010.
Erkkilä AT, Booth SL. "Vitamin K intake and atherosclerosis." Curr Opin Lipidol. 2008 Feb;19(1):39-42.
Gast GC, de Roos NM, Sluijs I, Bots ML, Beulens JW, Geleijnse JM, Witteman JC, Grobbee DE, Peeters PH, van der Schouw YT. "A high menaquinone intake reduces the incidence of coronary heart disease." Nutr Metab Cardiovasc Dis. 2009 Sep;19(7):504-10.
Geleijnse JM, Vermeer C, Grobbee DE, Schurgers LJ, Knapen MH, van der Meer IM, Hofman A, Witteman JC. "Dietary intake of menaquinone is associated with a reduced risk of coronary heart disease: the Rotterdam Study." J Nutr. 2004 Nov;134(11):3100-5.
