Nutrition News & Views

March 29, 2000
What Do You Know About Vitamin K? - March 2000/No. 1

Have you ever heard that vitamin K stops bleeding? There is some truth to this. Vitamin K was discovered in 1929 by a Danish scientist. The "K" comes from the Danish word koagulering, which means, "clotting". Vitamin K is necessary for blood clotting. This nutrient also helps to reduce the creation of certain kidney stones. New research shows that vitamin K may also be good for healthy bones. According to the American Dietetic Association, "Recent studies have looked at the role of vitamin K in preventing hip fractures. Studies found that women who consumed more vitamin K had 30% fewer fractures." Vitamin K may help improve bone thickness by increasing levels of a substance in the blood that helps to control the role of calcium in bone building.

People who are taking medications (such as Coumadin) to thin the blood, may need to cut down on foods high in vitamin K. Otherwise, vitamin K may prevent the medicine from working. It is not necessary to stop eating these foods, but it is important to keep daily amounts of vitamin K about the same each day. Increases or decreases that are sudden can affect the activity of Coumadin. According to the National Institute of Health, "foods with moderate vitamin K content, between 10-75 mcg (micrograms), need not be limited for people taking anticoagulants, as long as the same number of servings of these foods are eaten each day." It is best to check with your health care provider about what to eat when taking medicines to thin the blood.

Patients undergoing surgery may be given vitamin K injections before or after surgery. This helps to prevent too much bleeding.

Vitamin K can be found in leafy green vegetables and fruits, as well as fish and fish oils. Milk, eggs and cereals provide smaller amounts. The recommended daily intake is 80 mcg for men and 65 mcg for women. Foods high in vitamin K are listed in the table below.

Food Source Vitamin K Content (in mcg)
1 cup raw Kale 540
1/2 cup cooked Collard Greens 440
Brussels Sprouts (5) 289
1/2 cup cooked Broccoli 200
1/2 cup raw Spinach 106
1 Avocado 80.4

Poisoning from eating too many foods high in vitamin K is rare. High doses of vitamin K supplements may lead to a certain type of anemia, brain damage, and liver damage. A deficiency of vitamin K is also rare. Since bacteria in the digestive system make about half of the vitamin K the body needs, healthy persons can easily get the rest of the vitamin K needed through foods. There are medical conditions that may cause a deficiency in vitamin K. Diarrhea, use of antibiotics, liver disease, or absorption problems may lead to loss of the vitamin. Signs of low vitamin K levels in the blood include easy bleeding and bruising, frequent nosebleeds, and lengthened blood-clotting time.

Submitted by LaDana Fulmer, Mississippi State University Dietetic Intern
Distributed by Barbara McLaurin, Ph.D., R.D., L.D., Human Nutrition Specialist, MSU Extension Service, March 2000

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