The Benefits and Uses of Vitamin K

What You Need to Know About Vitamin K

Farm worker inspecting organic kale leaves
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Vitamin K is a nutrient that plays a key role in blood clotting. Found in a number of vegetables such as dark leafy green vegetables, vitamin K is also available in supplement form or as a topical cream. Additionally, a form of vitamin K known as menaquinone, or vitamin K2, is produced in the intestines by certain gut bacteria.

Uses for Vitamin K

Vitamin K is typically used to treat blood clotting conditions and vitamin K deficiency. Vitamin K supplements are also purported to promote bone formation and protect against bone diseases such as osteoporosis. In addition, some people take vitamin K to alleviate itching caused by primary biliary cholangitis (a chronic liver disease).

Proponents claim that applying vitamin K cream to the skin can minimize varicose veins, dark circles under the eyes, bruises, scars, and stretch marks, as well as reduce rosacea symptoms and speed up the healing of wounds and burns.

The Benefits of Vitamin K

Currently, there isn't enough scientific evidence to support the use of vitamin K for conditions other than 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 issues. Here's a look at some key preliminary findings:

Bone Health

Low vitamin K levels may be associated with low bone mineral density, according to a 2015 study published in the Journal of Clinical Biochemistry and Nutrition. The study's authors found that women with higher vitamin K intake had higher bone mineral density in the leg and low back compared to women with the lowest vitamin K intake.

In a clinical trial comparing treatment with vitamin K and the medication risedronate to risedronate alone, researchers did not find that vitamin K plus medication was more effective in preventing fractures than medication alone.

Heart Disease

Although some observational studies and preclinical animal-based studies have suggested a benefit from diets rich in vitamin K, studies involving supplements have not found the same positive effects. In a report published in the Cochrane Database of Systematic Reviews in 2015, for instance, researchers analyzed previously published trials of vitamin K supplementation for three months or longer. Only one small trial met the researchers' quality criteria. The study, which was short-term and conducted on healthy adults, found no effects for vitamin K on blood pressure or blood lipid levels.

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.

Forms of Vitamin K

Vitamin K1 (also known as phylloquinone) is the predominant form of vitamin K found in plants. A synthetic form of vitamin K1 known as phytonadione may also be used in dietary supplements.

Vitamin K2 (menaquinone) may be found in dietary supplements as MK-4 or MK-7.

A synthetic form of vitamin K3 known as menadione has been associated with liver cell damage in laboratory studies is no longer used therapeutically in dietary supplements or fortified foods.

Vitamin K is widely available in topical creams. In most cases, vitamin K creams also contain other natural substances (such as herbal extracts and plant oils).

Deficiency

Rare in adults, vitamin K deficiency may occur if the body can't properly absorb vitamin K from the intestinal tract. This problem may be caused by certain diseases (including malabsorption and gastrointestinal disorders such as cystic fibrosis, celiac disease, and Crohn's disease), long-term use of medications that interfere with vitamin K metabolism (such as certain antibiotics or blood-thinning medications), or treatment with hemodialysis. Signs and symptoms of vitamin K deficiency include excessive bleeding and bruising.

In newborn babies, vitamin D deficiency can occur in the early weeks due to low vitamin K transport across the placenta. Deficiency may cause a condition known as "vitamin K deficiency bleeding," or VKDB. VKDB may also occur later in infancy (during the second to twelfth week), particularly in exclusively breastfed babies or those with malabsorption conditions.

Side Effects and Safety

According to the Institute of Medicine Food and Nutrition Board's 2001 publication, there have been no reports of adverse effects associated with vitamin K consumption from food or supplements, however, caution may be warranted with intake above the recommended daily amount.

Certain medications may interact with vitamin K. People taking anticoagulants such as warfarin, for instance, must be monitored and maintain a consistent level of vitamin K due its effect on blood clotting factors. Therefore, if you take anticoagulant medication, you should not increase your intake of vitamin K from food or supplements without first consulting your physician

Other medications and supplements may decrease vitamin K levels. Antibiotics, for instance, may decrease levels of vitamin K2 (the form of vitamin K produced in the intestines by gut bacteria). In addition, vitamin K may interact with certain supplements (including coenzyme Q10, vitamin E). You can get additional tips on using supplements here.

Keep in mind that self-treating a condition and avoiding or delaying standard care may have serious consequences.

Using Vitamin K for Health

While vitamin K may help with certain health problems, self-treating a condition with vitamin K and avoiding standard care may have serious health consequences. If you are considering taking vitamin K in supplement form, talk to your doctor first to discuss whether it's appropriate for you and to determine a dosage.

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