While vital for managing certain health conditions, Coumadin presents challenges for monitoring diet and intake of nutrients that can impact its effectiveness. Your use of Coumadin will affect how much vitamin K you get from your diet. Vitamin K ensures proper clotting, whereas Coumadin thins blood and lessens the stickiness of platelets that form clots.
What Is Coumadin?
Coumadin is a brand name for the generic drug warfarin. Doctors have prescribed this blood thinner since the 1950s for patients at risk of deadly blood clots and to prevent heart attacks and strokes. Coumadin works in opposition to the health benefits of vitamin K, a nutrient essential for proper blood clotting. Because of Coumadin's effects on blood clotting, you will likely have to make several lifestyle changes when taking this drug, including close monitoring of your diet and vitamin K intake.
While on Coumadin, your doctor will advise regular blood tests, such as the International Normalized Ratio test, or INR. This test will help your doctor set the correct dosage for you by providing information about how well your medication is working. Along with the INR, the prothrombin time (PT) test is the standard testing for patients taking Coumadin. Your vitamin K intake will directly impact how Coumadin works for you. Your schedule for blood testing will depend upon your condition and your test history.
Vitamin K Sources
Your doctor may recommend that you eat and drink dietary sources that will keep your vitamin K consumption between 90 to120 mcg a day. Your most important task will be avoiding large swings in vitamin K intake to avoid risks associated with under- or overdosing Coumadin. Foods such as Swiss chard, kale and broccoli contain well over your daily requirement for vitamin K. One cup of chopped kale, for example, contains 547 mcg of vitamin K. You can still enjoy these foods, but you will need to limit your consumption. Because of vitamin E's effects on vitamin K, your doctor may also put restrictions on your your consumption of that vitamin.
Proper dosing of Coumadin is essential. The PT and INR tests provide the basis for your particular dosage and any changes you may need to make with your diet. The American Association for Clinical Chemistry recommends informing your doctor if you have eaten large amounts of beef or soybean products prior to testing so she can correctly interpret your results. Some herbal supplements may also affect Coumadin's effectiveness. Drugs.com recommends avoiding cranberries in any form as well as teas containing sweet clover or sweet woodruff. Your doctor will likely work closely with you to manage your diet. Taking Coumadin means you must increase your awareness of vitamin K sources and avoid large fluctuations in your intake.
- "Principles of Anatomy and Physiology"; G. Tortora et al.; 2005
- "Kidney International"; Warfarin-Related Nephropathy: Another Newly Recognized Complication of an Old Drug; D. Rizk and D. Warnock; July 2011
- Linus Pauling Institute; Vitamin K; Jane Higdon and Victoria J. Drake; May 2008
- Lab Tests Online; PT and INR; July 2011
- Drugs.com; Coumadin; December 2010