Vitamin K

Facts about Vitamin K

Vitamin K, also called phylloquinone or phytonadione, is the family name of fat soluble compounds that we need for the proper clotting of blood, bone formation and brain development. It is involved in electron transport and the conversion of food into energy.

Our body can produce this vitamin in our digestive system where it is synthesized by bacteria, absorbed into the blood, and mainly stored in our liver. Newborns don't have the necessary bacteria in their intestines to make Vitamin K and are therefore at risk of deficiency. A Vitamin K injection is usually given at birth to avoid brain damage or death.

The absorption of naturally occurring Vitamin K is poor. Although, the absorption rate increases when food is consumed with butter, it can still be as little as 10% compared to the absorption of a supplement form. High doses of Vitamin E may also interfere with the absorption and utilization of Vitamin K.

Benefits of Vitamin K

Vitamin K plays a crucial role in blood clotting and bone formation. It supports calcium transport, the calcification of bone, and may also help with:

  • coagulation disorders
  • cystic fibrosis
  • fractures
  • haemorrhages
  • hemorrhagic disease of the newborn (HDNB)
  • inflammatory conditions
  • morning sickness in pregnancy
  • osteoporosis
  • rheumatoid arthritis

Vitamin K Deficiency

A deficiency in adults is relatively rare but might occur due to certain drugs, antibiotics, mineral oil, diseases causing absorption problems, or heavy alcohol intake. Only small amounts of Vitamin K are transported across the placenta, putting newborns at risk of deficiency. Many countries therefore routinely give a Vitamin K injection at birth to prevent hemorrhagic disease of the newborn (HDNB).

Signs of deficiency include:

  • blood in stool
  • easy bruising
  • haemorrhage
  • impaired bone formation
  • internal bleeding
  • prolonged bleeding

Vitamin K Toxicity

According to the Food and Nutrition Board (2001), the form of Vitamin K, which is supplied in conventional foods and dietary supplements, has no reports of toxic effects. However, some rare reactions have occurred when given intravenously (a rare hypersensitivity-like reaction). Symptoms include:

  • alteration of taste
  • chest pain
  • cramp-like pain
  • difficulty breathing
  • dizziness
  • flushing
  • itchy or swollen skin
  • perspiration
  • rapid and weak pulse
  • redness
  • spasms

Important: Vitamin K can interfere with anti-clotting medicine.

Foods high in Vitamin K

The absorption of naturally occurring Vitamin K is poor. Although loss during cooking is minimal, the use of trans-fatty acids might further decrease absorption. Vitamin K can also be used as a preservative in food. Best sources are green leafy vegetables but good sources are also:

  • asparagus
  • broccoli
  • Brussels sprouts
  • cabbage
  • canola oil
  • cauliflower
  • collards
  • cucumbers
  • egg yolk
  • green tea
  • kale
  • lettuce
  • liver
  • margarine
  • soybean oil
  • spinach
  • tomatoes
  • turnip greens

The current Dietary Reference Intake (DRI 2001) established by the Food and Nutrition Board of the Institute of Medicine states for a healthy adult male 120mcg and for a healthy adult female 90mcg. Nutrient Reference Values (NRVs) for Australia and New Zealand are considerably lower with 70mcg for a healthy adult male and 60mcg for a healthy adult female.

Dietary reference intakes (DRI's) for Vitamin K are based solely on levels to maintain normal blood clotting, which has led to suggestion that much higher Vitamin K requirements may be needed to maintain our skeletal and vascular systems. Further studies in this area are needed.

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