The average American does not consume adequate vitamin K to benefit from the vitamin's blood clotting and bone building properties. Dried beans and peas are among the foods containing vitamin K, and another good source is pure soybean oil. However, about half of U.S. soybean oil is hydrogenated, according to the Institute of Shortening and Edible Oils in Washington, D.C. The vitamin K from hydrogenated oil does not have the same clotting or bone-forming protein, says Sarah Booth of the Vitamin K Laboratory at Tufts University in Boston.
Function
Vitamin K is a fat-soluble vitamin best known for regulating coagulation of the blood and its ability to bind calcium. Both uncontrolled clotting and uncontrolled bleeding are life-threatening. Because vitamin K is synthesized in the liver, severe liver disease may increase risk of hemorrhage. Vitamin K is necessary for the maintenance of bone, cartilage, and soft tissue, including blood vessels.
Sources
The body stores only a small amount of vitamin K, which depletes rapidly, requiring adequate daily intake from food. The recommended Daily Value, DV, for adult males, is 120 mcg and 90 mcg for women. Dried beans, such as chickpeas, garbanzo, pinto, navy and red kidney, contain a moderate amount of vitamin K but are not the best sources. One cup of cooked soybeans contains 33 mcg and 41 percent DV for vitamin K. Kidney beans provide 18.6 percent DV and almost 15 mcg per cup. Green peas are a better source, one cup containing 14.4 mcg, which is 52 percent DV. Leafy green vegetables provide much more vitamin K than legumes and, in comparison, one cup of boiled kale provides 1,062 mcg and 1,327 percent DV.
Bone Health
Vitamin K-dependent proteins in bone may help to prevent osteoporosis and bone fractures. A trial by the Nurses' Health Study, published in the "American Journal of Clinical Nutrition" concluded that a moderate to high intake of vitamin K lowered the risk of hip fracture in middle-aged and older women.
Regulation of Blood Coagulation
Newborn infants are routinely administered vitamin K after birth to prevent bleeding into the brain because the fetus has low levels of the vitamin needed for clotting. The University of North Carolina Memorial Hospital conducted a study to determine if the benefits of vitamin K, given to mothers prior to delivery, would transfer to their babies. They found vitamin K levels in babies from mothers who received the vitamin was significantly higher than levels in babies from mothers who did not receive it.
Decreased Risk of Cancer
Vitamin K may have preventive anticancer benefits, specifically for the lymphatic system. According to a United Press International report, researchers at the Mayo Clinic said that a higher intake of vitamin K reduced the risk of developing non-Hodgkin lymphoma by approximately 45 percent.
Deficiencies
Symptoms of vitamin K deficiency include easy bruising and excessive bleeding from nosebleeds, gums and menstruation. In addition, blood in the urine or stool or bones that easily fracture may indicate low vitamin K levels. In infants, vitamin K deficiency may cause bleeding in the head. Deficiencies can occur because of diseases that inhibit the production of fat, such as cystic fibrosis or celiac disease. Prolonged treatment with medications or oral antibiotics can cause a vitamin K deficiency due to the destruction of bacteria in the gut.
References
- USDA: Vitamin K: Another Reason To Eat Your Greens
- Oregon State University: Micronutrient Information Center: Vitamin K
- The World's Healthiest Foods: Vitamin K: Food Sources
- "The American Journal of Clinical Nutrition": Vitamin K Intake and Hip Fractures in Women: A Prospective Study: Discussion
- Obstetrics & Gynecology: The University of North Carolina Memorial Hospital: Vitamin K--Blood-Clotting Studies During Pregnancy and Aprothrombin and Proconvertin Levels in the Newborn: Summary
- United Press International: Health News: Vitamin K May Protect Against Lymphoma
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