V i t a m i n K
Vitamin K is a group of structurally similar vitamins, which includes Vitamin K1 and Vitamin K2, that the human body needs for modification of certain proteins required for blood coagulation, and in metabolic pathways in bone and other tissue.
Vitamin K1 is synthesized by plants and is found in large quantities in green leafy vegetables because it is directly involved in the photosynthesis, but it occurs in far smaller quantities in other plant tissues.
Vitamin K is necessary for normal blood clotting and synthesis of proteins found in plasma, bone and kidneys. Those with chronic kidney disease are at risk for Vitamin K deficiency. Additionally, in the elderly there is a reduction in Vitamin K2 production.
Human milk contains 1–4 μg per liter of Vitamin K1, while Vitamin K2 concentration in human milk appears to be much lower. Interestingly, bacteria in the colon (large intestine) can convert K1 into Vitamin K2, such as Escherichia coli.
Vitamin K and Vitamin D work in tandem for the bone metabolism and development, helping to bring calcium into the bones. Vitamin K modifies the protein osteocalcin, giving it the ability to bind to calcium. Calcium then forms into the bone matrix.
Missing Vitamin K results in calcium not bound into the bone matrix, and travels free in the blood, eventually deposited in the arteries, which causes a hardening of the arteries, a condition also known as atherosclerosis.
There is a protein (gas6) that is important for regulating cell growth, proliferation and preventing cell death. Its function is dependent on Vitamin K, which also helps cells to communicate with each other.
A research shows that total diabetes risk of individual who have highest circulating levels of vitamin K1 were 51% lower than those with the lowest levels.
120 µg RDA
RDA (recommanded dietary allowances) per day 
UL (tolerable upper intake level) per day
 Food and Drug Administration (FDA)