Coumadin, a brand of warfarin, treats and prevents blood clots, reducing the risk of heart attack, stroke and other related conditions. But the vitamin K in your diet also affects blood clotting, and it can reduce warfarin's effectiveness. If you're taking warfarin, talk to your doctor about managing your vitamin K intake to avoid any side effects.
Relationship Between Warfarin and Vitamin K
Some drugs, including warfarin, interact with nutrients in your diet. Understand that in order for warfarin to work effectively, you must keep your vitamin K intake as consistent as possible. Vitamin K is involved in your body's natural blood clotting process. Under normal circumstances, this plays an important role in preventing excess bleeding. For someone at risk, this natural process raises the chance of blood clots. Warfarin's effectiveness at reducing blood clots relies on its ability to block vitamin K.
Limit Foods High in Vitamin K
Consuming small amounts of vitamin-K-rich foods shouldn't cause a problem. Eating large amounts works against warfarin therapy, however. The recommended vitamin K intake is 90 micrograms per day for all adults. To keep your intake consistent, start by limiting foods high in vitamin K to no more than one serving daily. Leafy greens are typically high in vitamin K, so limit cooked kale, turnip greens, spinach, Swiss chard, collard greens and mustard greens. The serving size for these foods is 1/2 cup cooked. Parsley is high in vitamin K, too, so limit to only 1/4 cup raw per day.
Control Moderately High Vitamin K Foods
Some vegetables are moderately rich in vitamin K. A good starting point is to limit these foods to no more than three servings daily. Raw spinach and turnip greens, endive, broccoli, romaine lettuce, brussels sprouts and green leaf lettuce are on this list. The serving size is 1 cup, except for brussels sprouts, which is 1/2 cup. You'll get enough servings of vegetables in your diet by including vegetables low in vitamin K, such as corn, celery, beets, mushrooms, green pepper, potatoes and peeled cucumber.
Other Factors That Affect Warfarin
Alcoholic beverages and some dietary supplements interact with warfarin therapy. Your doctor may recommend avoiding alcohol while on this medication. If you do choose to drink, however, understand that having more than three drinks a day increases the effectiveness of warfarin, which raises your bleeding risk. A number of herbal supplements interfere with therapy. These include ginger, garlic, bilberry, dong quai, turmeric, willow bark and St. John's wort, but there are many others. Certain antibiotics and vitamin E supplements may cause problems as well. It's imperative to have your doctor approve any dietary supplements you plan to take.