Vitamin K Supplement Uses, Benefits, Dosages & Side Effects

Vitamin K is the name given to a group of fat-soluble vitamins involved in blood coagulation and bone metabolism.

Vitamin K helps the body to form blood clots and stops blood vessels from bleeding excessively in a process called hemostasis.

This vitamin is also important for maintaining heart health, building strong bones and various other physiological processes. It plays a role in regulating levels of calcium in the blood and is involved in wound healing.

Vitamin K can form a solution with lipids (fats) and the body stores it in both fat cells and the liver. [1] If you do not have adequate levels of this vitamin, you may experience excessive bleeding.

This article will discuss how vitamin K works in the body, the five different forms of this vitamin, common uses, known health benefits, deficiency symptoms, safety and side effects, and interactions. Food and supplement sources are also discussed.

Vitamin K

Vitamin Supplement

Bone Health

Blood Clotting

Heart Health

How It Works:

• Important for normal blood coagulation
• Supports cardiovascular health & function
• Supports healthy bone formation

Dosage:

120 mcg for Males; 90 mcg for Females

Safety:

Rated Likely Safe

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How Does Vitamin K Work in the Body?

In German, vitamin K is called “Koagulationsvitamin”. It is perhaps best known for its important roles in the body related to blood platelet coagulation.

The University of Maryland Medical Center (UMM) states that vitamin K is often called the “forgotten vitamin” and that its important benefits to health frequently go unrecognized. [1]

According to the National Institutes of Health (NIH), Vitamin K is actually a blanket name for a group of compounds called naphthoquinones. Vitamin K compounds are all chemically related and perform similarly in the body. [2]

These five forms of vitamin K are:

• Vitamin K1 (phytonadione)
• Vitamin K2 (menaquinone)
• Vitamin K3 (menadione)
• Vitamin K4 (menadiol sodium diphosphate)
• Vitamin K5 (4-Amino-2-methyl-1-naphthalenol) [2]

Of the five forms, vitamin K1 is the one that is found naturally in plants. It is also the most prevalent food-based source of naphthoquinones in humans.

The NIH states that vitamin K is needed for controlling calcium binding to proteins that form bones and other tissues. Without this vitamin, these proteins cannot bind to calcium.

This impairs clotting abilities, weakens bones and encourages abnormal calcification in soft tissues and blood vessels. [2]

Dr. Andrew Weil states that vitamin K is a necessary adjunct to vitamin D. He says if you are deficient in either vitamin D or K, then neither of them will be able to work as effectively inside the body. [3]

Only small amounts of vitamin K are stored in humans. Dr. Joseph Mercola states that prominent vitamin K researchers seem to agree that “just like with vitamin D, nearly everyone is deficient in vitamin K.” [4]

Dr. Mercola says that most people get enough vitamin K to allow them to form blood clots when necessary, but not enough to keep them safe from developing an array of serious health problems.

The UMM states that those with chronically low levels of vitamin K are more likely to develop varicose veins, atherosclerosis, cardiovascular disease, osteoporosis (brittle, fragile bones), several forms of cancer, brain dysfunction, tooth decay, and infectious illnesses like pneumonia. [1]

Babies are born with very low levels of this vitamin. Newborns typically are given an injection of Vitamin K shortly after birth to ensure proper clotting activity.

Vitamin K Uses and Health Benefits

The Natural Medicines Comprehensive Database (NMCD) lists dozens of uses that people take vitamin K supplements for including:

• Cancer
• Cardiovascular health
• Cognitive function
• Diabetes
• Normal blood clotting
• Menstrual cramps
• Osteoporosis
• Rheumatoid arthritis
• Tooth and gum health [5]

The NMCD has rated vitamin K as Effective for hemorrhagic disease, hypoprothrombinemia, vitamin k-dependent clotting factors deficiency (VKCFD), and Warfarin anticoagulation. It has also been rated as Possibly Effective for Osteoporosis.

According to NMCD, studies are currently investigating the effects of vitamin K supplementation in cardiovascular health, bone and joint disorders, bleeding disorders, cancer, diabetes, cystic fibrosis, osteoporosis, and strokes. [5]

Dr. Mercola says that vitamin K helps to prevent hardening of the arteries (atherosclerosis). He says this is likely due to it working to keep calcium out of the body’s soft tissues and artery linings (endothelium).

By preventing calcification in the coronary arteries, vitamin K might help to support cardiovascular health and reduce some of the risk factors linked to heart disease.

Enzymes are proteins that catalyze chemical reactions. Coenzymes are nonprotein compounds that are required for proper functioning in enzymes.

NIH reports that vitamin K is an important coenzyme for an enzyme called vitamin K-dependant carboxylase. This enzyme is involved in metabolizing bone tissue, blood clotting and a number of other physiological processes.

According to NMCD, population studies show that higher dietary intake of vitamin K2 from foods is correlated with a lower risk of:

• Coronary heart disease
• Coronary calcification
• Breast arterial calcification
• Mortality from coronary heart disease [5]

There have been promising results from studies using vitamin K for cancer, coronary heart disease, cystic fibrosis, hypercholesterolemia, multiple sclerosis, and rheumatoid arthritis.

However, these results are preliminary and Vitamin K supplements are not approved as drugs for the prevention or treatment of these conditions. More research is still needed to determine the therapeutic efficacy of this vitamin for these and other common uses.

Vitamin K1 is sold in both oral and injectable forms. It is approved as a prescription drug by the Food and Drug Administration (FDA) in the United States.

Low-dose K1 tablets are also available as dietary supplements, along with K2 pills. These products do not require a prescription to purchase online or in stores.

If you are interested in learning more about vitamin K supplements, then talk with your doctor about possible benefits for your specific health needs.

Vitamin K for Bone Health

Vitamin K is very important for building and maintaining healthy bones. Being deficient in this vitamin can increase the risk of osteoporosis and other bone problems.

Dr. Weil says one of the best ways to ensure healthy bones is to give the body the raw materials it needs to form and maintain them. He says this can be accomplished by ensuring adequate consumption of fresh, whole, raw, organic foods in the diet.

Increasing your intake of vitamin K helps to ensure that your body has the raw materials it needs to develop hard, strong bones. Dr. Weil says vitamin K “helps plug calcium and other important minerals into your bone matrix.” [3]

Studies in Japan show vitamin K supplementation in the form of 45 mg vitamin K2 daily not only reverses bone loss in osteoporosis, it even increases bone mass in some cases and reduces the risk of fracture. [5]

Dr. Mercola cites research from 7 different Japanese trials that show routine vitamin K supplementation reduces vertebral fractures by 60%, and non-vertebral fractures by 80%. [4]

Bone building inside the body is largely controlled by a protein that acts like a hormone called osteocalcin. According to researchers from the Netherlands, vitamin K2 is 300% more effective for raising osteocalcin levels than vitamin K1 is. [4]

Dr. Mercola says that bone health depends on more than just calcium. He says that bones are comprised of more than a dozen separate minerals.

He states that taking calcium alone will likely weaken the bones and increase the risk of osteoporosis; not strengthen and harden them. This is why using a complete bone supplement with multiple ingredients may be a better option.

The NMCD has rated vitamin K as Possibly Effective for osteoporosis. More research is needed to fully determine the effects vitamin K supplementation has on osteoporosis and other conditions that affect bone and joint health. [5]

You should discuss the possible bone health benefits of vitamin K with a qualified health professional to better understand them.

Cancer Research

There is some epidemiological data that suggests getting more of certain forms of Vitamin K in your diet could help to lower the risk of death from cancer. However, this data is preliminary and clinical trials are needed to confirm findings.

Vitamin K is being studied in in vitro models of breast, colorectal, liver, lung, and prostate cancer. [5] At this time the association between this vitamin and cancer-related mortality is unclear and contradictory. [5]

According to the NMCD, “One large population study involving healthy German patients suggests that people who consume more than 42-46 mcg of vitamin K2 (menaquinones) daily have a 27% reduced risk of cancer mortality but not cancer incidence compared to those who consume less than 23-26 mcg daily.” [5]

They also report that in another population study, people who consumed 630 mcg of vitamin K1 (phylloquinone) daily were found to have a 46% lower risk of cancer mortality in comparison to participants who consumed 171 mcg per day.

In another study, higher dietary intake of menaquinones (87 mcg per day) did not have a lower risk of cancer mortality compared to people with lower intake of 79 mcg daily. [5]

The difference in intake between these two groups is very small which may explain why no difference in mortality rates was observed.

Dr. Mercola references a study published in the International Journal of Oncology that found vitamin K to slow down the growth of lung cancer cells.

He also says that previous studies have shown vitamin K to be beneficial for treating cancers of the blood cells and lymphatic system (leukemia). [4]

According to Dr. Mercola, “Vitamin K has also been found beneficial in the fight against non-Hodgkin lymphoma, colon, stomach, nasopharynx, and oral cancers.” [4]

Vitamin K has not been studied enough to determine if or how it can affect carcinogenesis or cancer progression. It has not been approved by the FDA as a drug for the prevention or treatment of cancer.

Most available research is population studies, and more large-scale clinical trials are needed to determine the therapeutic efficacy of vitamin K for various cancers in humans.

Symptoms of Vitamin K Deficiency

Vitamin K deficiency is rare in healthy adults. This vitamin is found in various common foods and is synthesized within the intestinal tract by certain bacteria.

According to Dr. Weil, taking antibiotics sometimes kills the microorganisms that produce vitamin K, possibly causing mild deficiency. He says the following may also contribute to low levels: [3]

• Celiac disease
• Crohn’s disease
• Cystic fibrosis
• Excessive bleeding
• Gallbladder disease
• Liver disease
• Routine use of blood thinners like warfarin
• Ulcerative colitis
• Using statin drugs to lower cholesterol

According to the UMM, long-term hemodialysis and serious burns can also contribute to vitamin K deficiency.

Dr. Mercola suggests that those with family histories of cardiovascular disease and/or osteoporosis speak with their doctors about vitamin K supplementation. He says people who do not consume a lot of green leafy vegetables might benefit from a dietary supplement.

If you are deficient in this vitamin, you may experience some or all of the following symptoms:

• Increased bruising
• Secretions from the nose or gums
• Heavy menstrual flow
• Excessive bleeding from wounds
• Blood in urine or stool
• Increased prothrombin time (PT)
• Stomach pains or gastrointestinal bleeding
• Cartilage calcification
• Malformation of developing bones
• Accumulation of insoluble calcium salts in the arteries
• Potential for birth defects

Vitamin K Food Sources

Dark green leafy vegetables like spinach, kale, Swiss chard and dandelion greens are some of the best sources of vitamin K. Dr. Weil says phytonadione (vitamin K1) is directly involved in plant photosynthesis.

Vitamin K2 is the other natural form of vitamin K. It is comprised of a subset of ten compounds called menaquinones which are referred to as MK-1 through MK-10.

This form of vitamin K is found in animal muscle meat and organs, eggs, and certain dairy products, like cheese. [3]

MK-7 through MK-10 are also produced in the intestinal tract by colonic bacteria. However, the NMCD states that absorption of vitamin K2 from the colon is very limited. [3]

Dr. Mercola notes that because vitamin K is fat-soluble, it is good to consume healthy fats along with foods you eat. For instance, you could sauté Swiss chard in organic coconut oil to provide vitamin K1 and both medium- and long-chain fatty acids.

Dr. Mercola says that fermented foods normally have the highest amounts of vitamin K. A traditional Japanese food made from soybeans called natto is a rich source.

Many people in the US do not eat a lot of fermented foods or green leafy vegetables. Dr. Mercola says this contributes to the high rates of vitamin K deficiency that he and some other physicians believe exists.
Some foods he recommends that are high in vitamin K2 include raw cheese, raw butter, raw milk, kefir, and sauerkraut.

He recommends eating vitamin K2 foods from animals that have been grass-fed and raised in open-range environments when possible to get the highest vitamin levels.

The following are some foods that are rich in this vitamin and the amount each contains per serving:

• 3.5 ounces of natto contains roughly 1000 micrograms (1 mg) of vitamin K2
• 8 ounces of duck or lamb meat: 6 mcg
• 8 ounces of beef liver: 5 mcg
• 8 ounces of dark turkey meat: 5 mcg
• 8 ounces chicken liver: 3 mcg

Vitamin K Supplements

Of the five known vitamin K forms, K3, K4, and K5 are synthetic. That means they are not naturally occurring, and are manufactured in laboratories.

Vitamin K1 is chiefly associated with blood clotting and liver health. K2 is thought to be mainly helpful for maintaining healthy bones, blood vessels and other tissues besides the liver.

Vitamin K1 and K2 are the forms most commonly found in supplements. Dr. Mercola recommends vitamin K2 for supplementation purposes. [4]

The most common dosage of supplements is 100 mcg per dose. There are some higher-strength formulations available, with dosages of between 400-500 mcg, but these are less common.

Vitamin K is sometimes paired with vitamin D in combination supplement products. It has been seen in research that these two vitamins have a synergistic relationship in the body and that optimal levels of both vitamins are beneficial for bone and cardiovascular health.

The NMCD states that there are thousands of dietary supplement products that contain vitamin K. Not all supplements are equal in quality. Always choose high-quality, naturally-sourced supplements from reputable manufacturers.

Dosage Guidelines

The NIH reports the following adequate intake (AI) recommendations for vitamin K: [2]

• 2 mcg/day for infants between 0 and 6 months of age
• 2.5 mcg/day for infants between 7 and 12 months
• 30 mcg/day for children between 1 and 3 years
• 55 mcg/day for children between 4 and 8 years
• 60 mcg/day for children between 9 and 13 years
• 75 mcg/day for children between 14 and 18 years
• 90 mcg/day for women over 19
• 120 mcg/day for men over 19

Pregnant/nursing teens between 14 and 18 are advised to consume 75 mcg/day. Women over 19 years old who are pregnant or nursing are recommended to consume 90 mcg/day.

When taken as a dietary supplement, most formulations provide 100 mcg per dosage. Higher dosage supplements are also available that typically provide 400 mcg or 500 mcg per dosage.

Some dosages that have been used in various research trials include:

• Coronary heart disease: 500 mcg K1 per day for 3 years
• Cystic fibrosis: 1-5 mg per day
• Hypercholesterolemia (high cholesterol): 45 mg K2 per day for one year
• Hypoprothrombinemia (impaired blood clotting): 2.5-25 mg K1 per day
• Liver cancer: 45 mg K2 per day for up to 8 years
• Osteoporosis: 1-10 mg K1 per day, or 45 mg K2 per day up to 4 years
• Rheumatoid arthritis: 100 mcg K2 per day for three months

If you are interested in taking vitamin K supplements then speak with your doctor or healthcare provider. It is always recommended to consult with your doctor to help determine the best dosage for your needs.

Vitamin K Side Effects

The Natural Medicines Comprehensive Database has rated Vitamin K1 and K2 supplements as Likely Safe when taken orally and appropriately.

The NMCD states that vitamin K causes few side effects when taken orally. When administered intravenously, rare hypersensitivity reactions have been noted. [5]

Very rare side effects have been noted with high doses of vitamin K, including one case of hyperbilirubinemia (excess blood bilirubin) in a premature neonate (newborn).

According to Dr. Mercola, pregnant and nursing women should not exceed 65 mcg/day doses unless monitored by their physicians.

He says anyone with a history of cardiac arrest, ischemic stroke or blood clotting disorders should not use vitamin K supplements without discussing it with their doctors first. [4]

Drug and Supplement Interactions

Vitamin K can interact with some drugs, herbal supplements, and health conditions. The following interactions are reported by the NMCD.

Coenzyme Q10 can have additive effects when used with vitamin K. Using these two together can increase the risk of blood clotting, especially in those using anticoagulant medications or herbs.

Be careful using vitamin K supplements along with herbs with hypoglycaemic properties or herbs that cause blood sugar levels to decrease.

This combination might excessively increase sensitivity to insulin and/or reduce blood glucose levels after meals. Some of these herbs include ginseng, guar gum, fenugreek, turmeric, and ginger.

A thyroid hormone analogue called tiratricol might exacerbate the prothrombinemic effects of vitamin K. In theory, this could upregulate the breakdown of clotting factors that are dependent on this vitamin.

In animals, high doses of retinol (vitamin A) can antagonize the effects of vitamin K. Researchers are not yet sure if this occurs in humans as well.

Vitamin E (alpha tocopherol) can antagonize or inhibit vitamin K effects, possibly increasing the risk for bleeding in those with low levels, or those who routinely take Warfarin (Coumadin).

Vitamin E also seems to inhibit vitamin K absorption, and prevent its activities by binding to vitamin K-dependant enzymes.

Some drugs that can influence the absorption of vitamin K include antibiotics, anticonvulsants, bile acid sequestrants, mineral oil, rifampin, and orlistat.

If you have any serious health condition, or use any prescription medications, then speak with your doctor before beginning to use a vitamin K supplement.

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