Vitamin K

Roles
Vitamin K helps the body synthesize at least four of the proteins implicated in clot formation.
It also cooperates with vitamins A and D in helping to build bones and kidneys protein.

Intake
We need a really small amount of it every day but we do not know precisely how much.
We recommend:
For an adult: 45 micrograms daily
For a baby: 10 micrograms daily

Who is at risk of deficiency?
Since it is widely available in foods and since our intestine bacteria produce this vitamin, deficiencies in this vitamin are almost unknown.
Usually they are caused by an inability to absorb the vitamin rather than inadequate intake. It concerns:

People who do not absorb fats correctly (liver diseases, cystic fibrosis ...)
Patients who take antibiotics for a long time since the drugs can destroy the bacteria
Newborn babies have "bacteria free" intestines for the first few hours of their life. Vitamin K crosses the placenta poorly resulting in low fetal plasma concentrations of the vitamin and the breast milk is low on this vitamin.
It is recommended to supplement breast fed babies with 2 mcg of vitamin K per week.

Deficiency symptoms
If you do not get enough of this vitamin your blood does not coagulate normally. Your bleeding would be prolonged and could lead to hemorrhages.

Good vegetarian sources
Vitamin K is found in leafy green vegetables such as spinach, lettuce, watercress, leeks...
Other rich foods are: cabbage, Brussels sprouts, broccoli, cauliflower, green beans, peas, apple, eggplant, cereals, soybeans and vegetable oils. Ovo-vegetarians can also found this vitamin in eggs.

Cautions
It is a fat-soluble vitamin that can be stored in the body.
People who take vitamin K supplements (heart disease) should cut down foods high in vitamin K and avoid multivitamin pills which contain vitamin K.