Vitamin K

Pronunciation

Definition 1

A nutrient that the body needs in small amounts to function and stay healthy. Vitamin K helps to form blood clots (a mass that forms when blood platelets, proteins, and cells stick together) and maintain strong bones. It is fat-soluble (can dissolve in fats and oils) and is found in green leafy vegetables, broccoli, liver, and vegetable oils. Vitamin K is also made by bacteria that live in the large intestine. Not enough vitamin K can lead to bleeding and bruising. It is a type of phylloquinone. (NCI Dictionary)

Definition 2

The term "vitamin K" refers to a group of chemically similar fat-soluble compounds called naphthoquinones: vitamin K1 (phytonadione) is found in plants and is the primary source of vitamin K for humans through dietary consumption, vitamin K2 compounds (menaquinones) are made by bacteria in the human gut, and vitamin K3 (menadione) is a water-soluble preparation available for adults only. Vitamin K is necessary for the liver to produce the coagulation factors II, VII, IX, and X, as well as the clotting factors protein C, protein S, and protein Z; vitamin K deficiency can result in deficiencies of these coagulation factors and excess bleeding. An injection of vitamin K is routinely given to newborn infants to prevent vitamin K deficiency bleeding, also known as hemorrhagic disease of the newborn. Vitamin K deficiency is rare in adults but may result from chronic malnutrition or an inability to absorb dietary vitamins. (NCI Thesaurus)

Definition 3

Fat soluble vitamin that is a coenzyme during the synthesis of the biologically active form of a number of proteins involved in blood coagulation and bone metabolism. Vitamin K's structure typically consists of a methylated naphthoquinone ring from which one or more unsaturated aliphatic side chains are attached at the 3-position of the ring. (NCI Thesaurus/CRCH)

More information

Vitamin K helps your body by making proteins for healthy bones and tissues. It also makes proteins for blood clotting. If you don't have enough vitamin K, you may bleed too much.

Newborns have very little vitamin K. They usually get a shot of vitamin K soon after they are born.

If you take blood thinners, you need to be careful about how much vitamin K you get. You also need to be careful about taking vitamin E supplements. Vitamin E can interfere with how vitamin K works in your body. Ask your health care provider for recommendations about these vitamins.