The synthetic type of vitamin K, vitamin K3 (menadione), interferes with glutathione, which causes toxicity to animals.

The MK-7 and other bacterially derived forms of vitamin K2 exhibit vitamin K activity in animals. The most notable forms include MK-7 to MK-11. The most important forms of menaquinones contain 4 to 10 repeating isoprenoid units. They differ in structure from phylloquinone due to the 3-substituted lipophilic side chain. Bacteria are the primary producers of menaquinones, which they use during anaerobic respiration. This transformation takes place via the gut bacteria lengthening the isoprenoid side chain. A range of vitamin K2 forms can be created. Gut flora converts vitamin K1 into vitamin K2 (menaquinone).

Vitamin K2 is created in the gut by bacteria. It also can be converted into vitamin K2 in animals. Vitamin K1 is active in animals and is responsible for the production of coagulation factors. It is most prevalent in green leafy vegetables because it is directly involved in photosynthesis. Vitamin K1, also known as phylloquinone, is a product of plant synthesis. Vitamin K occurs in two bioactive forms, vitamin K1, and vitamin K2. Recent research has linked vitamin K deficiency to issues with osteoporosis and cystic fibrosis. Vitamin K deficiency impairs the coagulation process leading to issues with bleeding. The process of vitamin K carboxylation allows the coagulation factors to bind calcium ions, which further facilitates the cascade pathways. It is a co-factor for vitamin K-dependent carboxylation, which includes various enzymes. Vitamin K is essential for the synthesis of coagulation proteins. Vitamin K is found in foods and can be a dietary supplement. Vitamin K is a fat-soluble vitamin that affects coagulation pathways within the body.

Antidote for vitamin k