Coumadin, a brand of the drug warfarin, is a commonly used medication popularly known as a blood thinner. People with blood clots and certain types of heart rhythm disturbances may have to use Coumadin for a period between several months and a lifetime. Coumadin has many interactions with foods --- some enhance its effects, some counteract it. If you're prescribed Coumadin, it is important to familiarize yourself with foods to eat and those to avoid.
What Coumadin Does
Coumadin works by interfering with your body's natural path of blood clot formation. It counteracts the effect of vitamin K, which is necessary for these clots to form. When you take Coumadin, it takes longer for your blood to clot. Lab tests called INR and prothrombin time, or PT, show how long it takes your blood to clot. While undergoing treatment with Coumadin, the results need to be in a certain range, usually between 2 and 3. It's important that the result remain stable within this range, to prevent either clots from forming or an increased risk of bleeding.
Vitamin K and Coumadin
Vitamin K counteracts the effect of Coumadin. If you eat too much food containing vitamin K, you'll reduce the effectiveness of the medication and increase your risk for clots. You do not have to adopt a special diet, though you may need to eat less foods that are particularly high in vitamin K. You should maintain a consistent diet and not make any changes without consulting your doctor. Look over your diet, determine how much vitamin K you typically consume, and then try as much as possible to stick with the same diet.
Foods High in Vitamin K
Leafy green vegetables contain high amounts of vitamin K. Turnip greens and collard greens contain over 400 mcg in 1/2 cup. Kale and Swiss chard contain about 250 mcg in 1/2 cup. Other foods high in vitamin K include green scallions and broccoli. The National Institutes of Health recommends eating no more than one serving a day of the greens that are highest in vitamin K, and no more than three servings of foods that are moderately high, such as brussels sprouts, broccoli and spinach.
Drinks
Alcohol can alter the effect of Coumadin. Acute consumption can increase the risk of bleeding. Chronic alcohol use can decrease Coumadin's effectiveness. You should also avoid cranberry juice, which can increase the effect of Coumadin. Green tea contains a high amount of vitamin K, but when brewed, the amount is apparently negligible. Garlic, ginger, sweet clover and wheat grass are among the many substances that can affect clotting time, and are often in herbal teas. Read labels carefully, and consult your doctor with any questions about your diet.
References
- MayoClinic.com; Warfarin Diet: What Foods Should I Avoid?; Sheldon G. Sheps; May 2010
- "Harrison's Principles of Internal Medicine"; Anthony Fauci, et al.; 2008
- Office of Dietary Supplements of the National Institutes of Health: Important Information to Know When You're Taking Coumadin and Vitamin K; December 2003
- St. Luke's Family Practice: Dietary Considerations in Coumadin Patients
- National Institute on Alcohol Abuse and Alcoholism of the National Institutes of Health; Alcohol-Medication Interactions; October 2000
