Anticoagulants: Vitamin K and your diet

You need vitamin K to help your blood to clot and to keep your bones strong. If you are taking the blood thinner warfarin (Coumadin), you will need to keep the amount of vitamin K in your diet steady. If you vary the amount of vitamin K too much, your doctor may have to change your dose of warfarin often.

Most people who take warfarin can eat a normal diet. But it is important not to suddenly eat a lot more or a lot less food that is high in vitamin K than you normally do. Make sure you get about the same amount of vitamin K each day.

This Actionset can help you learn what foods contain vitamin K and how to eat the right amount of these foods so you can get the most benefit from your medicine.

Key points

• Warfarin helps prevent dangerous blood clots.
• Warfarin works best if your intake of vitamin K stays about the same each day.
• By learning what foods contain vitamin K, you can make sure you get about the same amount each day so your medicine can do its job.

 What foods contain vitamin K?
 Why is it important to get a steady amount of vitamin K?
 How to get a steady amount of vitamin K
 Where to go from here

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Foods that are high in vitamin K include:

• Cooked leafy green vegetables such as kale, spinach, turnip greens, collard greens, Swiss chard, mustard greens, seaweed, and beet greens.
• Broccoli, raw or cooked.
• Raw parsley.
• Green tea.

Foods that are medium-high in vitamin K include:

• Raw leafy greens such as spinach, green leaf lettuce, romaine lettuce, iceberg lettuce, and endive.
• Brussels sprouts, cauliflower, and asparagus

Vitamin K is also found in some multivitamins, supplements, and herbal products.

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Warfarin (Coumadin) is an anticoagulant. Anticoagulants are often called blood thinners, but they do not actually thin the blood. Instead, they increase the time it takes for a blood clot to form. This can help reduce your risk for heart attack, stroke, deep vein thrombosis, or pulmonary embolism.

Warfarin works by decreasing the action of vitamin K. Vitamin K helps your blood clot so wounds don't bleed too much.

When you are taking warfarin, you still need vitamin K in your diet. But it is important not to suddenly change the amount of vitamin K you eat each day. This could keep warfarin from working well.

• Eating a lot of vitamin K may decrease the effect of warfarin, making it more likely that blood clots will form.
• Eating much less vitamin K than normal may increase the effect of warfarin and increase your risk of bleeding.

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You do not need to stop eating foods high in vitamin K if you are taking warfarin. But you do need to eat about the same amount each day. To be successful:

• Learn how much vitamin K is in the foods you eat, and watch your portion sizes.
• Don't suddenly change the amount of vitamin K in your diet. Try to keep the amount you eat about the same from day to day. For example, if you don't regularly eat leafy greens, such as spinach, don't add them to your diet or eat a lot at once.
• If you take a multivitamin that contains vitamin K, be sure you take it every day.
• Check with your doctor before you take any supplements or herbal products. Some of these may contain vitamin K.

If you are used to eating foods that are high in vitamin K, you do not need to change your diet. What is important is to try to keep the amount about the same from day to day.

To keep a steady amount of vitamin K in your diet, it is a good idea to limit yourself to either:

1 serving a day of foods that are high in vitamin K, or

3 servings a day of foods that are medium-high in vitamin K.

For example:

• You could have a salad with 2 cups of mixed lettuces for lunch and 1/2 cup of cooked Brussels sprouts with dinner. That would be 3 servings for the day.
• If you do not normally eat much food that contains vitamin K, it would not be a good idea to have 2 cups of lettuce for lunch and then have 1/2 cup of cooked broccoli with dinner. The serving of broccoli is high in vitamin K and is the maximum amount you should have in one day. To be safe, have either the lettuce or the broccoli, not both.

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Now that you have read this information, you are ready to get a steady amount of vitamin K while you are taking warfarin.

Talk with your doctor

If you have questions about this information, take it with you when you visit your doctor. You may want to mark areas or make notes in the margins where you have questions.

If you would like more information on healthy eating while you are taking warfarin, the following resources are available:

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