Vitamin K

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Vitamin K plays a key role in blood clotting and bone health. There are certain blood thinning medications such as warfarin that require a strict amount of vitamin K consumption per day. Deficiency in vitamin K is uncommon, especially in the United States where most people get enough of this vitamin from their diet. Vitamin K is also produced by bacteria in the colon. Populations who are at an increased risk of deficiency include:

  • Newborns who do not receive an injection of vitamin K at the time of birth
  • Those with cystic fibrosis
  • Those with celiac disease
  • Those with ulcerative colitos (UC)
  • Those with short bowel syndrome
  • Those who have previously had weight loss surgery

Vitamin K deficiency can result in bruising and bleeding issues as blood clotting will be impacted by this deficiency.

Also known as:  Vitamin K1: Methylphytyl Naphthoquinone, Phylloquinone, Phytomenadione, Phytonadione, 2-Methyl-3-Phytyl-1, 4-Naphthoquinone. Vitamin K2: Menaquinone, Ménaquinone, Menatetrenone, Menatétrenone, MK-1, MK-2, MK-4, MK-5, MK-6, MK-7, MK-8, MK-9, MK-10, MK-11, MK-12, MK-13. Vitamin K3: Menadione, Ménadione, Menadione Sodium Bisulfite, 2-Methyl-1, 4-Naphthoquinone. Vitamin K4: Menadiol Diacetate, Menadiol Sodium Diphosphate, Menadiol Sodium Phosphate, Menadiolum Solubile Methylnaphthohydroquinone. Vitamin K5: 4-Amino-2-Methyl-1-Naphthol. Fat-Soluble Vitamin, Vitamina K, Vitamine K, Vitamine Liposoluble, Vitamine Soluble dans les Graisses.

Diseases and Conditions

Vitamin K is effective for the following conditions:

  • Hemorrhagic disease
  • Hypoprothrombinemia
  • Vitamin K-dependent clotting disorders
  • Warfarin anticoagulation

Vitamin K is possibly ineffective for intraventricular hemorrhage.

There is insufficient information on the effectiveness of vitamin K for the following conditions:

  • Breast cancer
  • Cancers
  • Colorectal cancer
  • Coronary heart disease
  • Cystic fibrosis
  • Diabetes
  • Hypercholesterolemia
  • Liver cancer
  • Lung cancer
  • Osteoporosis
  • Prostate cancer
  • Stroke


Vitamin K is likely safe when K1 (phytonadione) or vitamin K2 (menaquinone) is used orally and appropriately. Vitamin K1 (phytonadione) is also likely safe to use parenterally. Vitamin K1 (phytonadione) in oral and injectable form has been approved by the FDA as a prescription drug. It is likely safe for children, pregnant, and breastfeeding women to take vitamin K1 (phytonadione) orally and appropriately, and under the supervision of a physician.

Avoid use of vitamin K3 supplements as the U.S. Food and Drug Administration (FDA) has banned vitamin K3 (a synthetic menadione) from over-the-counter supplements, due to the potential for allergic reactions, hemolytic anemia, jaundice, and liver toxicity. Avoid use of menadiol (not available in the United States), due to the potential for damage to red blood cells, causing anemia (hemolysis). Intravenous or intramuscular vitamin K has been associated rarely with anaphylactoid reactions.

Medication Interactions

Vitamin K may interact with the following medications, particularly antidiabetic drugs:

  • Glimepiride (Amaryl)
  • Glyburide (DiaBeta, Glynase PresTab, Micronase)
  • Insulin
  • Pioglitazone (Actos)
  • Rosiglitazone (Avandia)
  • Chlorpropamide (Diabinese)
  • Glipizide (Glucotrol)
  • Tolbutamide (Orinase)
  • Warfarin (Coumadin)

Supplement and Food Interactions

Vitamin K may interact with the following supplements or foods:

  • Coenzyme Q-10
  • Devil's claw
  • Fenugreek
  • Guar gum
  • Panax ginseng
  • Siberian ginseng
  • Tiratricol
  • Vitamin A
  • Vitamin E


The U.S. Dietary Reference Intake for an adequate intake (AI) of vitamin K is as follows:

  • 120 mcg daily for adult males
  • 90mcg daily for adult females
  • 2-2.5mcg daily for infants
  • 30-75mcg daily for children and adolescents


Foods which contain vitamin K include:

  • Spinach
  • Broccoli
  • Asparagus
  • Watercress
  • Cabbage
  • Cauliflower
  • Green peas
  • Beans
  • Olives
  • Canola
  • Soybeans
  • Meat
  • Cereals
  • Dairy products

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