Important: This page is general information, not medical advice. It does not recommend or prescribe any treatment. Always consult your doctor or pharmacist before starting, stopping or changing any medicine.
About Vitamin K
Vitamins are substances that your body needs to grow and develop normally. Vitamin K helps your body by making proteins for healthy bones and tissues. It also makes proteins for blood clotting. If you don't have enough vitamin K, you may bleed too much.
Newborns have very little vitamin K. They usually get a shot of vitamin K soon after they are born.
If you take blood thinners, you need to be careful about how much vitamin K you get. You also need to be careful about taking vitamin E supplements. Vitamin E can interfere with how vitamin K works in your body. Ask your health care provider for recommendations about these vitamins.
There are different types of vitamin K. Most people get vitamin K from plants such as green vegetables, and dark berries. Bacteria in your intestines also produce small amounts of another type of vitamin K.
It sits within Food and Nutrition.
The lead U.S. institute for this subject is the NIH Office of Dietary Supplements.
When to speak to someone. Reading about a topic cannot tell you whether it applies to you. Speak to a doctor or pharmacist if symptoms are severe, sudden, getting worse, or simply not going away — and seek emergency care immediately for chest pain, breathing difficulty, sudden weakness or confusion, or a serious allergic reaction.
Research on Vitamin K
265 studies areregistered for this condition on ClinicalTrials.gov, the U.S. National Library of Medicine's public registry. A selection is below — the links go straight to the registry entry, not to a summary of ours.
What a registered study does and does not mean. Registration means a study exists and has been declared publicly. It says nothing about whether the treatment being tested works, is safe, or is available to you. Many studies find no benefit — that is what research is for. Never seek out an experimental treatment on the strength of a registry entry alone.
Research currently under way
- Plasma Lipids-Dependent Vitamin E Metabolism During Dynamic HyperlipidemiaNational Heart, Lung, and Blood Institute (NHLBI)
- The Role of Vitamin K on Knee Osteoarthritis OutcomesBoston University
- Post Marketing Observational Study on Safety of BALFAXAR vs. KCENTRA for Reversal of Vitamin K Antagonist Induced Anticoagulation in Adults Undergoing Urgent Surgery or Invasive ProcedureOctapharma
- Long-term Anticoagulation With Oral Factor Xa Inhibitor Versus Vitamin K Antagonist After Mechanical Aortic Valve ReplacementJoon Bum Kim
- Comparison of Anti-Thrombotic Treatments Between Aspirin and Warfarin During Initial Six Months After Bioprosthetic Heart Valve ReplacementAsan Medical Center
- Optimizing Anticoagulation in Pregnancies With Mechanical Heart ValvesMount Sinai Hospital, Canada
Research already completed
- The Efficacy and Safety of Non-vItamiN K antaGonist oraL Anticoagulants for intermEdiate Stroke Risk in Patients With Atrial Fibrillation (SINGLE-AF)Yonsei University
- Factors Associated to the Instability of the INR (International Normalized Ratio ) in the Prevention of Thromboembolism AVK (Anti Vitamin K) in Atrial Fibrillation in the Elderly: Instead of ComorbiditiesNantes University Hospital
- Aortic Calcification and Vitamin K AntagonistsCentre Hospitalier Universitaire, Amiens
Study data from ClinicalTrials.gov, a service of the U.S. National Library of Medicine. Retrieved 2026-07-30. Registry entries are supplied by study sponsors and investigators; ClinicalTrials.gov does not verify their scientific validity. PocketsInfo is not affiliated with, and not endorsed by, the NLM or the NIH.
Where to read more
Rather than paraphrase, we point you to the primary sources. Every link below is to a government health agency, a national institute or a recognised medical body — grouped by what you are trying to find out.
Learn More
- Find a Nutrition ExpertAcademy of Nutrition and Dietetics
- Protect Your Baby from BleedsCenters for Disease Control and Prevention
- Rare Clotting Factor DeficienciesWorld Federation of Hemophilia
- Vitamin KNational Institutes of Health, Office of Dietary Supplements
- Vitamin KHarvard School of Public Health
- Vitamin K deficiency bleeding of the newbornMedical Encyclopedia
Clinical Trials
- ClinicalTrials.gov: Vitamin KNational Institutes of Health
Medical subject headings
Clinicians and researchers index this subject under Vitamin K. These are the terms to use when searching medical literature.
This page is built from the MedlinePlus health topic record for Vitamin K, a service of the U.S. National Library of Medicine (NLM), National Institutes of Health. Information is from MedlinePlus.gov. PocketsInfo is not affiliated with, and is not endorsed by, the NLM or the NIH. Retrieved 30 July 2026.