vitamin K

Last reviewed 01/2018

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.