Function:
Vitamin K functions as a coenzyme during the synthesis of a number of proteins involved in blood coagulation and bone metabolism.

Recommended Dietary Allowance:
120 mcg for men and 90 mcg for women.

Deficiency:
There have been reports that a lack of the vitamin may be related to bone disease, including the development of osteoporosis. Studies to clarify this are now in progress. Blood coagulation problems have rarely been attributed to vitamin K deficiency. Although vitamin K is a fat-soluble vitamin, the body stores very little of it and it is rapidly depleted without regular dietary intake.

Sources:
Dietary sources include all leafy green vegetables, egg yolks, soybean oil, and liver.

Toxicity and UL:
No toxic effects have been reported from vitamin K intake, so a UL has not established.

Recommendation:
Supplementation in someone with a well rounded diet is not necessary. A supplement, however, can be safely taken to insure adequate intake. Individuals taking anticoagulant medication need to avoid supplements with vitamin K and vitamin E unless recommended and monitored by their physician.

For more information visit:
http://osu.orst.edu/dept/lpi/infocenter/vitamins/vitaminK/
or
http://www.coumadin.com/consumer/INT_VitaminK1.asp