Warfarin, the generic name for Coumadin, is among the top 20 drugs prescribed in the United States, according to the IMS Institute for Health Informatics. Coumadin is prescribed for those with deep-vein thrombosis and atrial flutters and others who have had strokes, heart attacks and certain operations. If your doctor has recommended warfarin therapy, it's vital that you understand the possible dietary interactions.
Warfarin & Vitamin K
Vitamin K is required for blood clotting. Certain proteins involved in blood coagulation require this vitamin for proper functioning. A deficiency in vitamin K can lead to excessive bleeding. If you take warfarin, however, you face the opposite problem. Certain health conditions cause excessive coagulation, leading to dangerous blood clots that could travel to the brain or heart. Warfarin helps lower this risk by reducing vitamin K's effects on blood coagulation. This extends the length of time it takes for a clot to form.
Dietary Vitamin K
Vitamin K is found in many healthy foods, including many vegetables, so excluding them from your diet is not recommended if you're on warfarin. What you do need to be cognizant of is the amount of vitamin K you're consuming. Keeping your vitamin K intake consistent each week is important. A sudden drop in vitamin K intake could increase the effects of warfarin, while increased intake could reduce the drug's effectiveness.The National Institutes of Health recommends eating no more than one daily serving of food high in vitamin K and no more than three servings of foods moderately rich in the vitamin.
Vitamin K Foods
Knowing what foods are rich in vitamin K is essential while you're on warfarin therapy. Many cooked leafy greens are at the top of the list; these include boiled spinach, kale, mustard greens, turnip greens and collards. Fresh parsley is also high in vitamin K. Foods with moderate vitamin K content include raw spinach, boiled Brussels sprouts, raw broccoli and uncooked turnip greens. Fresh lettuces -- including romaine, endive and green leaf -- also make the list. Olestra, used in many snack foods as a fat replacement, also contains vitamin K.
Other Dietary Concerns
Avoid cranberries and their juice, as they can interact with warfarin, according to the Ohio State University Medical Center. Consuming more than three alcoholic drinks a day can increase the drug's effects; your physician may advise you to avoid alcohol altogether. Talk with your physician about any dietary supplements you take, because they may cause unsafe interactions, as well. The National Institutes of Health Clinical Center cautions that vitamin E supplements may raise your risk of excessive bleeding. Herbal preparations used for medicinal purposes -- including St. John's wort, garlic, ginger and ginseng -- can also interact with warfarin.
References
- Linus Pauling Institute; Vitamin K; Jane Higdon, PhD; May 2004
- National Institutes of Health Clinical Center: Coumadin and Vitamin K
- NYU Medical Center; Managing Your Wafarin (Coumadin) Therapy: A Patient's Guide; March 2002
- Ohio State University Medical Center: Diet and Warfarin (Coumadin)
- IMS Institute for Healthcare Informatics; The Use of Medicines in the United States: Review of 2010; April 2011
