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For Warfarin: Eating a Consistent Vitamin K Diet

Warfarin is a medicine that helps keep your body from forming dangerous blood clots. This could prevent a heart attack or stroke. That’s a very important benefit. But like all medicines, warfarin should be used correctly. Among other things, that means watching your intake of vitamin K while taking this medicine. Vitamin K plays a key role in blood clotting. Warfarin reduces the clotting activity of vitamin K. That makes it harder for your body to form new, harmful blood clots. It also helps keep existing clots from growing larger.

A sudden change in your vitamin K intake may throw off the balance between the vitamin and your medicine, however. That can affect the medicine’s anti-clotting action. Getting more vitamin K than usual could make it easier for your body to form clots. Getting less vitamin K could lead to dangerous bleeding. To prevent these highs and lows, you need to consume about the same amount of the vitamin every day. This diet aims to prevent such issues by helping you get a steady amount of vitamin K.

Does this diet have any risks?

Be careful about any changes that could affect how warfarin works. Talk with your provider before starting a weight loss plan or other big diet change. Also check with your provider or pharmacist before taking any new dietary supplements. That includes multivitamins and herbal products containing garlic, ginkgo biloba, or green tea.

What foods should you eat?

Vitamin K is found in a wide array of foods, including many that are good for you. The goal is not to cut vitamin K out of your diet. Instead, aim to get a steady amount of it.

To do that, try to follow the same general eating pattern every day. The healthiest option is a balanced diet that includes:

  • Vegetables of varied types and colors

  • Fruits, especially whole fruits

  • Grains, with a focus on whole grains

  • Lean protein foods, such as fish, shellfish, poultry, lean meats, eggs, beans, nuts, and tofu

  • Fat-free or low-fat milk and dairy products

  • Healthy oils, such as many vegetable oils and the oils in foods such as fish and nuts

Dark green leafy vegetables are major sources of vitamin K. These veggies are packed with nutrients, and you don’t have to skip them. Just be sure that you also choose some vegetables that are lower in vitamin K. Examples are corn, mushrooms, onion, potato, summer squash, and sweet potato. This helps meet your nutrient needs while controlling your vitamin K intake.

Which foods should you limit?

Certain foods contain a lot of vitamin K. When you take warfarin, these foods may affect your medicine results. That’s especially true if you eat them only occasionally or in large amounts. Following are some vitamin K-rich foods:

  • Dark green leafy vegetables, such as broccoli, collards, kale, mustard greens, and spinach

  • Certain other vegetables and fruits, including asparagus, Brussels sprouts, and kiwifruit

  • Certain soy products, such as natto (a traditional Japanese dish of fermented soybeans)

Some vegetable oils also contain significant amounts of vitamin K. Examples are soybean and canola oils. Consider using other heart-healthy oils, such as corn and peanut oils.

Aim for the same total amount of foods high in vitamin K from day to day. For example, if you normally have 2 daily servings of these foods, don’t suddenly switch to 4 servings or none.

Tips for following this diet

Alcohol can affect how your body breaks down warfarin. That may increase the risk of serious bleeding. Don't drink alcohol every day while taking this medicine. Ask your provider whether an occasional alcoholic drink is OK.

Tell your provider if you have vomiting or diarrhea lasting more than a day, or if you can’t eat normally for several days for any reason. These issues may affect your warfarin dose.

Suggestions for planning meals

To prevent overloading on foods high in vitamin K, have small portions and combine them with foods lower in the vitamin. Below are some meal ideas. But keep in mind that the daily amount of vitamin K you should get depends on your usual eating style.

  • Oatmeal sprinkled with chopped nuts, served with a bowl of sliced kiwifruit* and strawberries

  • A veggie omelet filled with kale*, diced sweet red pepper, and reduced-fat cheese, served with a whole grain English muffin

  • A grilled chicken sandwich on whole grain bread with raw spinach*, tomato slices, and mustard

  • Oven-roasted fish served with steamed broccoli* and medley of whole grain pasta, carrots, onions, and mushrooms

* Foods higher in vitamin K

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