Scientists now know that Vitamin K plays a role in blood clotting, bone formation, and regulation of multiple enzyme systems.

Sources
Vitamin K is found in large amounts in green leafy vegetables, usually at levels greater than 100 mcg/100 g. The amounts of the vitamin in dairy products, meats, and eggs tend to vary, ranging from 0 to 50 mcg/g, and fruits and cereals usually contain approximately 15 mcg/g. Breast milk tends to be low in vitamin K and does not provide enough of the vitamin for infants younger than 6 months of age.

Deficiency

The predominant sign of vitamin K deficiency is hemorrhage, which in severe cases can cause fatal anemia.

DRIs
Infants:   2-2.5 mcg/day, depending on age
Young children:   30­-55 mcg/day, depending on age
Older children and adolescents:   60­-75 mcg/day, depending on age
Adults:   90­-120 mcg/day, depending on gender
Pregnant:   75-­90 mcg/day, depending on age
Lactating:   75­-90 mcg/day, depending on age