Vitamin K is a group of fat-soluble organic compounds:
- vitamin K1 - phylloquinones: present in green vegetables and fruit
- vitamin K2 - menaquinones: synthesized by bacteria within the gut
Vitamin K plays an essential role in blood clotting by acting as a cofactor for the post-translational carboxylation of glutamate residues in clotting factors II (prothrombin), VII, IX and X by the liver.
Bile salts and fat are required for absorption, and triglyceride-rich lipoproteins seem to be the major carriers of vitamin K in the plasma. Vitamin K is stored in the liver and spleen.
Dietary sources include leafy vegetables such as spinach, cabbage and cauliflower, certain legumes, and some vegetable oils such as rapeseed and soyabean oils.
Last reviewed 01/2018