Vitamin K is another fat-soluble vitamin essential for body functions. It comes in 2 forms: phylloquinone (vitamin K1) and menaquinone (vitamin K2). 
Vitamin K1 is the main dietary form of vitamin K and is present abundantly in plant sources, whereas K2 is available through fermented foods and animal sources, but only in small quantities. 
Vitamin K helps to make various proteins that are needed for blood clotting and the building of bones. 
Vitamin K is found throughout the body including the liver, brain, heart, pancreas, and bone. It is broken down very quickly and hence rarely reaches toxicity level. 
Compared to the other fat-soluble vitamins, very small amounts of vitamin K circulate in the blood. 
Symptomatic vitamin K deficiency and impairment of normal haemostatic control in healthy adults may take more than 2–3 weeks to develop at ‘low’ phylloquinone intake (i.e. < 10 mcg/day).