Alternative Names menadione, phylloquinone, menaquinones, phytomenadione
Definition Vitamin K is a fat-soluble vitamin. It is able to be dissolved in fat. Vitamin K is carried throughout the body by fat. The body needs a small amount of fat in the diet for absorption. The body can store fat-soluble vitamins. Phytomenadione is the natural form of vitamin K. Menadione is the synthetic form of vitamin K. Menaquinone is the form that is produced in the body. Vitamin K is made in the body, as well as obtained from the diet.
What food source is the nutrient found in? Vitamin K can be found in the following foods:
green leafy vegetables
members of the cabbage family including broccoli, cauliflower and Brussels sprouts
Intestinal bacteria manufacture some vitamin K in the body.
How does the nutrient affect the body? Vitamin K makes several proteins that help blood to clot when bleeding. It also makes other proteins for blood, bones and kidneys. Along with vitamins A and D, vitamin K is important for strong bone development.
Information There is no RDI for vitamin K.
Vitamin K deficiency is rare. It is often the result of impaired absorption rather than lack of the nutrient in the diet. Newborns are susceptible to vitamin K deficiency because their digestive tracts contain no vitamin K-producing bacteria. It is normal to administer an injection of vitamin K to newborns for this reason. The major symptom of vitamin K deficiency is blood that's slow to clot. Prolonged use of antibiotics could cause a problem because they destroy some bacteria in the intestines that help to produce vitamin K.
No symptoms have been observed when consuming too much vitamin K. Moderation is always the best policy. The most toxic form is supplements. For people taking blood thinning medications, such as aspirin or warfarin, it's important to be consistent with the intake of vitamin K-rich foods because the vitamin's pro-clotting properties counteract the medication.
Author: Clare Armstrong, MS, RD Reviewer: HealthAnswers Australia Medical Review Panel Editor: Dr David Taylor, Chief Medical Officer HealthAnswers Australia Last Updated: 1/10/2001 Contributors Potential conflict of interest information for reviewers available on request
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