Vitamin K aids in clotting, bone health

Vitamin K, an important factor in blood clotting, was named for the German word for clotting, koagulation, when the vitamin was discovered in the 1930s. This essential vitamin is found in many foods, including leafy green vegetables, vegetable oils, eggs, milk, butter, meat and some cheeses. Some vitamin K is also produced in the body by natural bacteria in the intestines.

Uses: Vitamin K is used to counteract overdoses of blood-thinning drugs and prevent a disease that causes bleeding in newborns. Vitamin K is sometimes taken to help strengthen bones and prevent osteoporosis.

Dose: The recommended daily allowance varies by age and sex, but a healthful diet provides enough for most people. In general, infants need 5 to 10 micrograms per day, and children need 15 to 65 micrograms, depending on age. Men should get at least 70 to 80 micrograms a day and women 60 to 65.

Precautions: Vitamin K supplements can counteract the effects of warfarin, a blood thinner. People allergic to the vitamin may experience nausea or a rash, but allergies are rare.

Research: Some research has shown that vitamin K improves bone density and helps prevent bone fractures. Studies are investigating the effects of a synthetic form of the vitamin on several types of cancers.

Dietary supplement makers are not required by the U.S. government to demonstrate that their products are safe or effective. Ask your health-care provider for advice on selecting a brand.

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-- Elena Conis