Vitamin K

Vitamin K is a group of compounds called napthoquinones. The primary dietary compounds are phylloquinones in plants and menaquinones in meat. Vitamin K acts as a cofactor for an enzyme that modifies an amino acid, glutamine. This modification is essential to the proper function of many proteins involved in blood clotting, such as thrombin and fibrin. In fact, the K moniker comes from the german ‘koagulation’. 

Vitamin K deficiency is rare, and causes vitamin K deficiency bleeding. Dark green leafy plants such as spinach and kale are excellent sources of vitamin K, as are most plants in the Brassica family, such as Brussel sprouts and broccoli.