|Description||Vitamin K is a fat-soluble vitamin.|
|Function/ Used for||Vitamin K is required for the formation of several of the proteins, called ‘clotting factors’ that regulate blood clotting, which means it helps heal wounds.
Vitamin K is also required for the formation of some proteins which are important for the maintenance of healthy bones and teeth
EU NRV: 75µg
UK average daily intake
UK dietary intake is unknown.
|As a supplement||Commonly available as a single supplement.
Different multivitamin and minerals products will vary in the percentage NRVs they include. People should always check the label for information about a specific product.
|Found in (dietary sources)||Green vegetables such as kale and spinach, potatoes, liver, soya beans and vegetable oils.
Vitamin K is also synthesised by gut bacteria and this contributes significantly towards the daily requirement of the vitamin.
|Precautions and contraindications||Safe Upper Level: 1000µg/day1|
|Use in pregnancy and breastfeeding||There is no evidence of adverse effects in pregnancy at normal intakes.
New-born infants are routinely given vitamin K injections or supplements.
|Interactions e.g. with other medications||Those taking anti-coagulants (such as warfarin) should not take supplements containing over 100mg Vitamin K except on the advice of a doctor.
Antibiotics can destroy vitamin K producing bacteria in the gut and may increase requirements for vitamin K.
The weight-loss drug orlistat and cholesterol-reducing drugs may reduce the absorption of vitamin K and other fat-soluble vitamins (A, D, E)2,3
|Adverse effects||None known.|
|References||1. Expert Group on Vitamins and Minerals, 2003.
2. Mason, P. Dietary Supplements. Pharmaceutical Press, London, 2001.
3. Gaby, A. R. A-Z Guide to Drug-Herb-Vitamin Interactions. HealthNotes 2006.