Warfarin, often known by its brand name, Coumadin, is a widely prescribed anticoagulant that thins the blood to prevent blood clots from forming. Patients with atrial fibrillation, mechanical heart valves, and those who have had heart attacks are routinely given Coumadin prescriptions. Vitamin K is essential for blood clotting, and warfarin decreases its effects, making vitamin K the antidote for warfarin overdose. Patients on warfarin therapy must keep their vitamin K intakes consistent.
Monitoring Warfarin Levels
Regular blood work to check prothrombin time, PT, and international normalized ratio, INR, is required of patients on warfarin. PT and INR measure the length of time needed for a blood sample to clot. Blood work is normally checked once a month for those taking warfarin. Your health-care provider will determine the desired range of your INR.
Herbs and Supplements
Many herbs and supplements affect INR. Tell your health-care provider about any vitamins, supplements, herbs and other over-the-counter preparations you take. Along with vitamin K, cat's claw, St. John's wort, willow bark, garlic, ginger, ginko and dong quai are just a few supplements known to affect INR. Vitamin E can increase the risk of bleeding. Certain antibiotics can interfere with warfarin, so if you are prescribed antibiotics and take warfarin, be sure to notify your cardiologist and pharmacist.
Foods High in Vitamin K
When taking warfarin, you must consume a consistent amount of vitamin K to prevent fluctuations of the warfarin levels. Avoid large amounts of soybean or canola oil. Do not consume foods or juices made from cranberries. Ask your health-care provider about eating licorice. Foods extremely high in vitamin K, with more than 200 percent of the recommended daily value, include kale, boiled spinach, turnip and mustard greens, collards and chards. Limit these foods to no more than one serving daily.
Foods moderately high in vitamin K should be limited to no more than three servings daily. These foods include Brussels sprouts, broccoli, endive, Romaine lettuce and raw spinach.
Warnings
If you experience serious adverse effects after eating foods that contain vitamin K, seek medical attention immediately. Hives, rash, difficulty breathing or swallowing, chest pain, swelling of hands or feet, numbness or tingling, and muscle or joint pain are among the most serious adverse effects. Symptoms of overdose or warfarin toxicity include bloody, red or tarry bowel movements; coughing up blood; pink, red or dark brown urine; vomiting what looks like coffee grounds; and small, flat, round red spots under the skin.
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