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Vitamin K

Alternative
Vitamin K Vitamin
names

Vitamin K deficiency; Deficiency - vitamin K
Definition

Vitamin K is a fat-soluble vitamin that plays an important role in blood clotting.

Function

Vitamin K is known as the clotting vitamin, because without it blood would not clot. Some studies indicate that it helps in maintaining strong bones in the elderly.

Food Sources

Vitamin K is found in cabbage, cauliflower, spinach and other green leafy vegetables, cereals, soybeans, and other vegetables. Vitamin K is also made by the bacteria that line the gastrointestinal tract.

Side Effects

Vitamin K deficiency is very rare and occurs when there is an inability to absorb the vitamin from the intestinal tract. Vitamin K deficiency can also occur after prolonged treatment with oral antibiotics.

Individuals with vitamin K deficiency usually have an increased propensity to bruising and bleeding.

Recommendations

Recommended dietary allowances (RDAs) are defined as the levels of intake of essential nutrients that the Food and Nutrition Board judges to be adequate to meet the known nutrient needs of almost all healthy persons.

Specific recommendations for each vitamin depend on age, gender, and other factors (such as pregnancy). The U.S. Department of Agriculture offers a PDF file that lists these recommendations.

The best way to get the daily requirement of essential vitamins is to eat a balanced diet that contains a variety of foods from the food guide pyramid.

It is important for people taking warfarin (a blood thinner) to know that vitamin K or foods containing vitamin K may reduce the effectiveness of this medication. Ask your health care provider before increasing intake or for advice on maintaining proper levels of vitamin K if you are taking warfarin.

Forms of vitamin K: The name "Vitamin K" refers to a group of chemically similar fat-soluble compounds called naphthoquinones. Vitamin K1 (phytonadione) is the natural form of vitamin K, which is found in plants, and provides the primary source of vitamin K to humans through dietary consumption. Vitamin K2 compounds (menaquinones) are made by bacteria in the human gut, and provide a smaller amount of the human vitamin K requirement. Vitamin K1 is commercially manufactured for medicinal use under several brand names (Phylloquinone, Phytonadione, AquaMEPHYTON, Mephyton, Konakion). A water-soluble preparation is available for adults only as vitamin K3 (menadione).

Natural sources: Vitamin K is found in green leafy vegetables like spinach, broccoli, asparagus, watercress, cabbage, cauliflower, green peas, beans, olives, canola, soybeans, meat, cereals, and dairy products. Cooking does not remove significant amounts of vitamin K from these foods. People who eat a balanced diet including these foods are likely ingesting enough vitamin K and do not require supplementation.

Blood clotting: Vitamin K is necessary for normal clotting of blood in humans. Specifically, vitamin K is required for the liver to make factors that are necessary for blood to properly clot (coagulate), including factor II (prothrombin), factor VII (proconvertin), factor IX (thromboplastin component), and factor X (Stuart factor). Other clotting factors that depend on vitamin K are protein C, protein S, and protein Z. Deficiency of vitamin K or disturbances of liver function (for example, severe liver failure) may lead to deficiencies of clotting factors and excess bleeding. For example, if prothrombin levels fall to 10-15% of normal levels, bleeding may occur even with minor traumas. If prothrombin levels fall beneath 10%, potentially serious spontaneous bleeding (hemorrhage with no clear cause) may occur.

Deficiency: Vitamin K deficiency is rare, but can lead to defective blood clotting and increased bleeding. People at risk for developing vitamin K deficiency include those with chronic malnutrition (including those with alcohol dependency), or conditions which limit absorption of dietary vitamins such as biliary obstruction, celiac disease or sprue, ulcerative colitis, regional enteritis, cystic fibrosis, short bowel syndrome or intestinal resection (particularly of the terminal ileum, where fat-soluble vitamins are absorbed). In addition, some drugs may reduce vitamin K levels by altering liver function or by killing intestinal flora (normal intestinal bacteria) that make vitamin K (for example, antibiotics, salicylates, anti-seizure medications, and some sulfa drugs). Vitamin K is routinely given to newborn infants to prevent bleeding problems related to birth trauma or when surgery is planned.

Warfarin (Coumadin): Warfarin is a blood-thinning drug that functions by inhibiting vitamin K-dependent clotting factors. Warfarin is prescribed by doctors for people with various conditions such as atrial fibrillation, artificial heart valves, history of serious blood clot, clotting disorders (hypercoagulability), or placement of indwelling catheters/ports. Usually, blood tests must be done regularly to evaluate the extent of blood thinning, using a test for prothrombin time (PT) or International Normalized ratio (INR). Vitamin K can decrease the blood thinning effects of warfarin, and will therefore lower the PT or INR value. This may increase the risk of clotting. Therefore, people taking warfarin are usually warned to avoid foods with high vitamin K content (such as green leafy vegetables), and to avoid vitamin K supplements. Conversely, vitamin K is used to treat overdoses or excess anticoagulant effects of warfarin, or to reverse the effects of warfarin prior to surgery or other procedures.

Dosing

The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.

Dietary intake
Foods rich in vitamin K: Green, leafy vegetables such as spinach, broccoli, asparagus, watercress, cabbage, cauliflower, green peas, beans, olives, canola, soybeans, meat, cereals, and dairy products. Cooking does not remove significant amounts of vitamin K from these foods.

Adults (18 years and older)
Vitamin K deficiency: Management should be under medical supervision. If the PT is only slightly elevated and poor dietary intake is thought to be the cause, increasing the ingestion of vitamin K-rich foods can be tried. In non-emergency situations, oral vitamin K1 (Phytonadione, AquaMEPHYTON, Mephyton, Konakion) can be given in a daily dose of 5-10mg (single doses up to 25mg are given in some cases). If there is a concern of bile salt deficiency or malabsorption in the ileum, a water-soluble oral form of vitamin K can be considered. If necessary, vitamin K1 can be injected at a dose of 10mg, repeated after 8-12 hours, or administered daily until the deficiency is corrected.

Elevated PT/INR (warfarin reversal): Management should be under medical supervision. Generally, if the INR is higher than intended but less than 6, and the patient is not bleeding, then warfarin can be held for 2-3 days then restarted when the range is acceptable. If the INR is 6-10 without bleeding, then 1-2mg of vitamin K1 (Phytonadione, AquaMEPHYTON) can be given subcutaneously. If the INR is greater than 10 without bleeding, then 3mg of vitamin K1 can be administered subcutaneously. In cases of serious bleeding or very high INR (greater than 20), 10mg of vitamin K1 can be given subcutaneously with fresh frozen plasma or prothrombin complex concentrate. If oral administration is preferred, doses between 50-200mg have been given. During treatment, blood tests for PT/INR should be followed to check for normalization. If the PT/INR does not correct, a physician should consider causes such as severe liver disease or disseminated intravascular coagulation (DIC). In urgent situations, a dilution of vitamin K can be given intravenously, although there is a risk of serious allergic (anaphylactoid) reactions. In cases of life-threatening bleeding, hospitalization and treatment with fresh frozen plasma (FFP) may be necessary.

Pre-procedure (warfarin reversal): Management should be under medical supervision. In general, for minor procedures such as tooth extractions, some eye operations, or biopsies, reversal may not be necessary if the INR is 2.5 or lower. For more serious procedures, the approach depends on the initial reason for anticoagulation. For patients taking warfarin for prosthetic heart valves, the warfarin can be held for four days prior to surgery while the patient is given low-molecular-weight heparin for up to 12 hours before the procedure. Warfarin can be restarted after surgery. For patients with atrial fibrillation or cardiomyopathy, warfarin can be held for four days prior to surgery, and then restarted afterwards. In high-risk patients with a history of deep venous thrombosis (DVT) or a pulmonary embolus (PE), after warfarin is held, intravenous unfractionated heparin coverage can be given until six hours before surgery, then restarted 12 hours after surgery. Warfarin can then be restarted. More aggressive measures may be necessary in patients with recent or multiple past blood clots. In patients with a history of an arterial clot, warfarin can be held for four days, and the INR can be checked on the day before surgery. If the INR is greater than 1.7, then 1mg of vitamin K can be given subcutaneously. On the day of surgery, if the INR is still elevated, fresh frozen plasma should be administered.

Acute liver dysfunction: A minority of patients with severe acute liver dysfunction has subclinical vitamin K deficiency at the time of presentation, which is corrected by a single dose of intravenous K1. The intestinal absorption of mixed-micellar K1 has been shown to be unreliable in adults with severe acute liver dysfunction.

Children (younger than 18 years)
Recommended dose at birth: Vitamin K1 given by injection has been shown in newborns and young infants to prevent "hemorrhagic disease of newborn," also known as vitamin K deficiency bleeding (VKDB). The American Academy of Pediatrics therefore recommends administering a single intramuscular injection of 0.5 to 1mg of vitamin K1 to all newborns. Oral dosing is generally not regarded as adequate for prevention, particularly in breastfeeding infants.

Warfarin toxicity/reversal: Should be under strict medical supervision. Initial doses of 1-5mg of vitamin K1 (Phytonadione, AquaMEPHYTON) have been used, with daily increases based on PT/INR values.

Note: Menadiol (not available in the U.S.) should not be given to infants or children due to rare reports of liver damage and blood cell toxicity (hemolytic anemia).

Safety

The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.

Allergies
Intravenous or intramuscular vitamin K has been associated rarely with anaphylactoid reactions, including shock, heart attack, respiratory arrest, and death. Therefore, these routes of administration should be avoided if possible. If given intravenously, preparations should be dilute and administration should be slow, under strict medical supervision.

Skin hypersensitivity reactions are rare, and may occur in particular with injections of vitamin K1 (Phytonadione, AquaMEPHYTON). A raised, itchy plaque may arise at the injection site which may take 1-2 months to resolve, and can cause a scar.

Side Effects and Warnings
Gastrointestinal: An unusual taste in the mouth has been rarely reported with vitamin K injections. Liver damage has been reported rarely in infants and children with use of the vitamin K preparation Menadiol (not available in the U.S.). Conditions that interfere with absorption of ingested vitamin K may lead to deficiency, including short gut, cystic fibrosis, malabsorption (various causes), pancreas or gall bladder disease, persistent diarrhea, sprue, or ulcerative colitis.

Skin (Dermatologic): Red, painful swelling at vitamin K injection sites has been reported. A raised, itchy plaque can arise at the injection site which may take 1-2 months to resolve, and can cause a scar. Transient flushing has been reported.

Neurologic: Dizziness has rarely been reported with vitamin K injections.

Blood (Hematologic): Damage to red blood cells causing anemia (hemolysis) has been reported rarely in infants and children with the use of the vitamin K preparation Menadiol (not available in the U.S.). This type of vitamin K should be avoided in people with glucose-6-phosphate dehydrogenase (G6PD) deficiency, because vitamin K may cause hemolytic episodes. Vitamin K deficiency decreases blood factors needed for clotting, and increases the risk of bleeding.

Cancer: Although initial concerns were voiced about the possible cancer risk of universally administering vitamin K by injection to newborns, there is no scientific evidence to support this risk. This is generally considered not to be a concern in the medical community.

Pregnancy and Breastfeeding
Pregnancy: Vitamin K is categorized by the Food and Drug Administration (FDA) as Pregnancy Category C. There is not sufficient scientific evidence in animals or humans to clearly conclude the effects on the fetus. Vitamin K given to mothers soon before birth is generally not recommended. Regular supplementation with vitamin K during pregnancy (beyond normal dietary intake) may increase the risk of jaundice in the newborn.

Birth: The American Academy of Pediatrics recommends administering a single intramuscular injection of vitamin K1 to all newborns to prevent vitamin K deficiency bleeding (VKDB), a potentially life-threatening condition. Excessive amounts of vitamin K supplementation in newborns may lead to serious complications, including hemolytic anemia, hemoglobinuria, kernicterus, brain damage, or death. Reactions may be particularly severe in premature infants.

Breastfeeding: Vitamin K ingested by mothers is generally considered to be safe during breastfeeding. There is very little vitamin K transmitted to infants through breastmilk (as opposed to many infant formulas which do include vitamin K). It is not known if the amount of vitamin K in breastmilk is increased if mothers take vitamin K supplements, but the scientific evidence suggests that this likely would make little if any difference. If an infant formula is used that is not fortified with vitamin K, a physician should be consulted to find another way for the infant to receive vitamin K.

Interactions

Most herbs and supplements have not been thoroughly tested for interactions with other herbs, supplements, drugs, or foods. The interactions listed below are based on reports in scientific publications, laboratory experiments, or traditional use. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy.

Interactions with Drugs
Warfarin (Coumadin): Warfarin is a blood-thinning drug that functions by inhibiting vitamin K-dependent clotting factors. Warfarin is prescribed by doctors for people with various conditions such as atrial fibrillation, artificial heart valves, history of serious blood clot, clotting disorders (hypercoagulability), or placement of indwelling catheters/ports. Usually, blood tests must be done regularly to evaluate the extent of blood thinning, using a test for prothrombin time (PT) or International Normalized Ratio (INR). Vitamin K can decrease the blood thinning effects of warfarin, and will therefore lower the PT or INR value. This may increase the risk of clotting. Therefore, people taking warfarin are usually warned to avoid foods with high vitamin K content (such as green leafy vegetables), and to avoid vitamin K supplements. Conversely, vitamin K is used to treat overdoses or excess anticoagulant effects of warfarin, or to reverse the effects of warfarin prior to surgery or other procedures. Over-the-counter vitamin K1-containing multivitamin supplements disrupt warfarin anticoagulation in vitamin K1-depleted patients. Vitamin K-depleted patients are sensitive to even small changes in vitamin K1 intake.

Antibiotics: Some antibiotics may decrease the bacteria in the human gut (which synthesize a small amount of the human vitamin K requirement). Broad-spectrum antibiotics, particularly sulfonamides such as Bactrim, may lower vitamin K levels, and increase the risk of deficiency in people not ingesting adequate amounts.

Salicylates (aspirin): High doses may increase vitamin K requirements.

Antacids: Sucralfate or high doses of aluminum hydroxide antacids may decrease absorption of fat-soluble vitamins such as vitamin K.

Cholestyramine (Questran), mineral oil: May decrease absorption of oral vitamin K and increase vitamin k requirements.

Quinine, Quinidine: May increase vitamin K requirements.

Dactinomycin: This cancer chemotherapy drug may decrease the effects of vitamin K and increase vitamin K requirements.

Menadiol interactions: Menadiol sodium diphosphase is a form of vitamin K that is not used in the U.S. Multiple drugs may cause complications when taken with Menadiol.

Interactions with Herbs/Supplements
Anticoagulant herbs: Vitamin K may decrease the blood thinning effects of herbs that act like warfarin (Coumadin) in the body by decreasing clotting factors made in the liver. In particular, this may apply to herbs with coumarin constituents, such as alfalfa ( Medicago sativa ), American ginseng ( Panax quinquifolium ), angelica ( Angelica archangelica ), anise ( Pimpinella anisum ), asafetida ( Ferula asafetida ), celery ( Apium graveolens ), chamomile ( Matricaria recutita ), fenugreek ( Trigonella foenum-graecum ), horse chestnut ( Aesculus hippocastanum ), prickly ash ( Zanthoxylum spp), quassia ( Picrasma excelsa ), and red clover ( Trifolium pratense ).


Other useful Vitamin information: Vitamin B-9 | Beta Carotene | Vitamin C

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