Vitamin K is essential for good health. Without it, bleeding would become uncontrolled, your bones would weaken. and your soft tissues and arteries would be susceptible to calcification. Although vitamin K toxicity from food sources is very rare, certain conditions can cause you to become deficient in this important vitamin, causing serious side effects. In addition, some medical conditions and medications, when combined with vitamin K supplements, can have adverse effects on your health.
What Is Vitamin K?
Vitamin K was identified by a Danish scientist in 1929 who named it koagulation, which is Danish for, of course, coagulation. Vitamin K isn’t just one vitamin. It's composed of a pair of natural fat-soluble vitamins: Vitamin K1(phylloquinone), and vitamin K2 (menaquinone). Each vitamin K plays similar as well as individual roles in your health.
Functions of K Vitamins
The function of vitamin K1 is primarily for the synthesis of a unique protein that has coagulation properties to control bleeding in your body, says News Medical Life Sciences. The benefits of vitamin K2 extend past just blood clotting.
One of vitamin K2's most important functions is to regulate calcium. By promoting calcification in bones and teeth, vitamin K2 improves bone density. Vitamin K2 prevents calcium from being deposited in the kidneys and helps reduce the formation of kidney stones. Vitamin K2 also offers cardiovascular benefits by preventing calcification of your arteries, which helps reduce the risk of heart disease.
Among other health benefits of vitamin K is the potential role in insulin metabolism by increasing testosterone in males and influencing growth in adolescence, according to CanPrev. Vitamin K is also important in pregnancy and to the health of newborns.
Sources of Vitamin K
30 micrograms for children aged 1 to 3
55 micrograms for children aged 4 to 8
for children aged 9 to 13
for children aged 14 to 18
for adult females; 120 milligrams for adult men
Phylloquinone Because of its role in photosynthesis, vitamin K1 is found mainly in the leaves of plants such as leafy greens, spinach, kale, turnip greens, collards, Swiss chard, parsley and romaine. The cruciferous family of vegetables, including broccoli, brussel sprouts, cauliflower and cabbage, also contain vitamin K . Some fruits contain vitamin K such as prunes, kiwi, avocado, berries and dried fruit. Vitamin K1 is best absorbed when consumed with other sources of fat.
Menaquinone In contrast, vitamin K2 is produced by bacteria in your intestine, according to Merck Manual. Vitamin K2 can be found in sources that involve microbial activity, such as animal products, including meat, dairy, eggs, yogurt and fermented cheese, and soybeans. Due to refrigeration, sources of vitamin K2 are not as prevalent as they once were because the general population no longer relies on fermented food, says CanPrev.
Signs of Vitamin K Deficiency
Normally, vitamin K deficiency is uncommon in healthy adults because it is synthesized by bacteria in the intestine, stored in the liver and recycled as needed. Since vitamin K2 is involved in bone and heart health, signs of a deficiency often remain undetected until it’s too late. The buildup of plaque in arteries and bone loss may take years to be detected. Blood tests to measure how quickly your blood clots are necessary to determine a diagnosis.
- Easy bruising of the skin
- Frequent nosebleeds or bleeding gums
- Excessive bleeding from a wound
- Bleeding in the GI tract causing blood in the urine or stool
- Bleeding in the stomach causing bloody vomit
- Heavy, painful menstrual cycles
- Joint pain and inflammation
- Osteopenia (bone loss)
- Frequent bone fractures
Who’s at Risk for Deficiency?
- Overuse of anticoagulants such as warfarin
- Use of barbiturates and salicylates
- Diseases that decrease fat absorption, such as biliary
stones, primary biliary cirrhosis and chronic cholestasis
- Conditions that cause malabsorption such as Crohn's
disease, cystic fibrosis, pancreatitis and colitis
- Diseases that produce coagulation
inhibitors such as paraproteinemia and myeloma
- Prolonged use of some antibiotics, anticonvulsants or
- Diet lacking in vitamin K or restricting the fat in your
Vitamin K in Newborns
Only a minimal amount of vitamin K passes from the mother to the fetus during pregnancy. Newborns are unable to synthesize vitamin K until their guts start to develop the required bacteria. For this reason, all newborns are generally given a vitamin K injection. Since breast milk contains only a small amount of vitamin K, breastfed infants who have not received this injection are at risk. If the mother has taken anticonvulsants, certain antibiotics or anticoagulants, the baby may have an increased risk of vitamin K deficiency. Formulas for infants contain vitamin K.
Vitamin K Toxicity and Precautions
When consumed orally, the natural fat-soluble vitamins K1 and K2 do not cause hypervitaminosis K symptoms — they are not toxic, even in large amounts.
However, toxicity can be caused by menadione, sometimes called vitamin K3, which is a synthetic, water-soluble vitamin K precursor that is used in supplements. Merck Manual notes that menadione should not be taken to treat vitamin K deficiency.
Too much vitamin K may lower blood sugar levels. If you have diabetes, be sure to monitor your blood sugar levels closely if you take a vitamin K supplement.
Don't take vitamin K with anticoagulants, such as warfarin (Coumadin). Vitamin K helps blood to clot — warfarin is used to slow blood clotting. The two substances have a major interaction and can affect how well your medication works, increasing your risk of bleeding.
Vitamin K is not effective to treat clotting problems caused by liver disease. It can actually worsen your condition.
If you have kidney disease, avoid taking excessive amounts of vitamin K. It can cause harmful side effects if you're receiving dialysis treatments.
Osteoporosis and Arthritis
Osteoporosis affects an estimated 200 million women worldwide. Due to calcium being the main mineral in bone, vitamin K2’s ability to build and maintain bone density plays a critical role in bone health.
Osteoarthritis is the most common form of arthritis, with knee osteoarthritis being the leading cause of disability among older adults in the U.S. Because of vitamin K2's role in regulating skeletal mineralization and its potential as a preventive option for treating osteoarthritis and osteoporosis, a study was conducted to examine the relationship between knee osteoarthritics with vitamin K deficiency. Findings, published in the American Journal of Medicine in 2013, verified that participants with subclinical vitamin K deficiencies had an increased incidence of osteoarthritis.
The European Food Safety Authority supports the use of high dose vitamin K to improve bone health. However, to investigate how a low dose of vitamin K benefits bone density, a three-year study in 2013 assessed bone mineral density of the lumbar spine, hip and neck in postmenopausal women who were given a low-dose of vitamin K2. From the findings, published in the journal Osteoporosis International, conclusions were that a lower dose of vitamin K is useful in the prevention of bone loss in postmenopausal women. Further investigation was needed to confirm similar results in children and men.
Vitamin K and Periodontal Health
Many nutrients play a role in dental health, and vitamin K2 may be especially important in preventing tooth decay. Vitamin K2 activates a protein called osteocalcin, needed to bind calcium to bone. This stimulates the growth of new dentin. Dentin is the calcified tissue that makes up the enamel of your teeth.
To assess the relationship of dental plaque and optimal nutrition, a study found that the antioxidants in vitamin K2 play an important role in the prevention of tooth decay. In the results of the study, published in the journal Medical Hypotheses in 2015, researchers found nutrition to be a dominant factor in the health of tooth enamel and suggested vitamin K2 as a viable supplement, especially in children, to prevent tooth decay.
Vitamin K Helps Your Skin
Vitamin K has been shown to benefit not only your bones and heart, but your skin too. In addition to reducing post-operative bleeding after cosmetic surgery, vitamin K may improve the appearance of burst capillaries, symptoms of rosacea and dark circles under the eyes, according to News Medical Life Sciences.
Derivatives of vitamin K applied topically as a cream resulted in a reduction of redness of the skin in a 2018 study published in the Journal of Clinical and Experimental Dermatology Research. The study aimed to assess the safety and effectiveness of cosmetics containing vitamin K on skin with vascular problems. After the four-week study, participants found that the cream increased hydration; did not have any adverse reactions such as burning, itching or pustules; and did not decrease melanin levels. Conclusions indicated that the accelerated effect of vitamin K on blood coagulation makes dilated blood vessels less visible.
Vitamin K Treatment for Cancer
Cancer is the second-leading cause of mortality worldwide. The World Health Organization says 9.6 million people die from cancer each year. Consistent results of clinical studies in animals indicate vitamin K2 may be a significant inhibitor of tumor growth in cancers, including leukemia, colorectal, ovarian, pancreatic and lung cancer.
In an effort to determine an alternative for chemotherapy, a review, published in Oncology Letters in 2018, summarized the effects of vitamin K2 as a potential anti-tumor agent in vivo and in vitro. Conclusions of the study found that vitamin K2 showed positive results in inhibiting cancer cells. Researchers suggested that vitamin K2 is extremely promising for the prevention of cancer without toxicity. They recommended that further investigation be made on the effects of vitamins and minerals in the treatment of cancer.
- News Medical Life Sciences: What Is Vitamin K?
- CanPrev: Vitamin K2: A Complete Primer
- Dietary Guidelines 2015: Nutritional Goals for Age-Sex Groups Based on Dietary Reference Intakes and Dietary Guidelines Recommendations
- Merck Manual: Vitamin K
- VitaminK2: Vitamin K2 Status Checklist
- News Medical Life Sciences: Vitamin K Deficiency
- WebMD: Vitamin K
- OpenHeart: The Health Benefits of Vitamin K
- The American Journal of Medicine: Vitamin K Deficiency Is Associated With Incident Knee Osteoarthritis
- Osteoporosis International: Three-Year Low-Dose Menaquinone-7 Supplementation Helps Decrease Bone Loss in Healthy Postmenopausal Women
- Medical Hypotheses: A Hypothetical Role for Vitamin K2 in the Endocrine and Exocrine Aspects of Dental Caries
- Journal of Clinical & Experimental Dermatology Research: The Evaluation of the Efficacy of Derivatives of Vitamin K
- News Medical Life Sciences: Vitamin K: Uses
- World Health Organization: Cancer
- Oncology Letters: Research Progress on the Anticancer Effects of Vitamin K2
- Critical Reviews in Biotechnology: A Potential Biotechnological Process for the Sustainable Production of Vitamin K1