Vitamin K is a fat-soluble vitamin that plays an important role in blood clotting and bone building. Two variants are known, phytomenadione (vitamin K1) found in green plants and menaquinone (vitamin K2) produced by intestinal bacteria.
The body provides the essential amount of vitamin K from these two types: vitamin K1, extracted from ingested food, and vitamin K2, produced in the gut by intestinal bacteria. With proper nutrition and healthy intestinal flora, the body’s vitamin K supply can be maintained.
Vitamin K1 is essential to activate blood clotting factors, which block the bleeding by closing the opening on the vessel wall in case of an injury. In its absence, hemophilia may develop.
Vitamin K2 plays an important role in keeping bone density at an appropriate level. Its deficiency reduces the level of active osteocalcin, thus increasing the chance of developing bone fractures and osteoporosis. Maintaining adequate levels of vitamin K2 in women in the climacteric period is, therefore, crucial to preserve bone density.
Vitamin K1 is found in large amounts in green leafy plants such as spinach, broccoli, lettuce, cabbage, kale, and in eggs and milk. A natural source of vitamin K2 are foods made by bacterial fermentation, such as matured cheeses.