Join Our Email List DVT & PE Stories Find info on a: Specific Medicine or Treatment Type of Medicine or Treatment Condition or Medical Procedure ClotCare complies with the HONcode standard for trustworthy healthinformation: verify here. ClotCare is a member organization of the Coalition to Prevent Deep Vein Thrombosis. Click here to learn more about the Coalition to Prevent Deep Vein Thrombosis and DVT Awareness Month, which is held each March. Vitamin K and Warfarin: What You Should Know Henry I. Bussey, Pharm.D., FCCP, FAHA Many people recognize that there is a relationship between warfarin and vitamin K, but often, they do not fully understand this relationship. So, what do you need to know about vitamin K and warfarin? First, you should know that your liver uses vitamin K to make blood clotting proteins. In doing so, vitamin K plays a role in your body's natural clotting process. Warfarin works against vitamin K. Specifically, warfarin reduces your liver's ability to use vitamin K to produce normally functioning forms of the blood clotting proteins.
By reducing the liver's ability to use vitamin K to produce normally functioning forms of the blood clotting proteins, warfarin reduces your risk of forming a blood clot. So how does my intake of vitamin K affect my warfarin therapy? A significant change in your intake of vitamin K can result in a significant, and potentially dangerous, change in your INR. For example, if you reduce the amount of vitamin K in your diet, your INR will increase. Also, reducing the amount of vitamin K in your diet may make it more difficult to manage your warfarin therapy. Patients who have a low intake of vitamin K have been found to have more fluctuation in their INR, which is the test used to measure the effect of warfarin and to adjust the dose of warfarin. For more information on the INR, please review the Understanding the PT-INR Test section of ClotCare. Why would a diet low in vitamin K make my INR more difficult to manage? Suppose you have a diet that is extremely low in vitamin K. Now suppose you eat a spinach salad at dinner one night.
Spinach salad is high in vitamin K, so you have just increased your vitamin K intake for the week. Because your diet is so low in vitamin K, this increase in vitamin K intake represents a huge change in your vitamin K intake for the week. For example, maybe eating the spinach salad increased your vitamin K intake by 50%. The result of this significant increase in vitamin K will be a significant drop in your INR. On the other hand, say you have a diet that has a moderate intake of vitamin K. In eating the spinach salad, you may have increased your vitamin K intake for the week, but rather than increasing your intake by 50%, you increased it by only 5%. The bottom line is that if your diet is extremely low in vitamin K, then any changes to your vitamin K intake represent large fluctuations in your vitamin K intake, which may translate to large fluctuations in your INR. So, if I am on warfarin, should I avoid eating foods that contain vitamin K? By now you should know that the answer to this question is "no."
It is a common misconception that people on warfarin should avoid vitamin K. As is indicated above, reducing your vitamin K intake can cause your INR to increase and may make it more difficult to control. Rather than avoiding vitamin K, you should maintain a consistent intake of vitamin K by maintaining a consistent diet. In other words, from week to week, you should eat the same types of foods. In order to maintain a consistent intake of vitamin K, you need to know something about the vitamin K content of the foods you eat. As a "rule of thumb", green vegetables, especially leafy green vegetables, and certain oils have a high content of vitamin K. Most fruits, meats, dairy products, and grains are low in vitamin K. As a resource to use in making consistent dietary decisions, ClotCare provides a list of certain foods and their relative content of vitamin K (i.e. low, moderate, or high). Click here to download this list. You can also click here for information on the vitamin K content of foods available on the NutritionData website.
Finally, probably the best thing you can do to help your anticoagulation clinician manage your warfarin therapy effectively is to communicate to him any changes in your life that might affect your warfarin. You should inform your clinician of any dietary changes you make, preferably before making them. For answers to other frequently asked questions about warfarin therapy, go to our FAQs About Warfarin (Coumadin) section. Click here to view full list of new postingsArticle by Laura Earl, RN, BSN, CACP If you have been diagnosed with a blood clot, a medication named warfarin (Coumadin) may be prescribed as part of your treatment to prevent further blood clots. You may need to take warfarin (Coumadin) for a few weeks, months, or the rest of your life. While taking warfarin (Coumadin), there are a few things about vitamin K you will need to know. Vitamin K is a naturally occurring vitamin. Vitamin K is primarily found in leafy green vegetables such as spinach, broccoli, and lettuce, and enters your body when you eat these foods.
Vitamin K is produced by the bacteria in your intestines, and it is also in vitamin and nutritional supplements. Your body uses vitamin K to produce some of the clotting factors that helps blood clot. Warfarin (Coumadin) works by interfering with how your body uses vitamin K. The metabolism of warfarin (Coumadin), vitamin K, and vitamin K dependent clotting factors takes place in your liver. Warfarin (Coumadin) prevents the production of vitamin K dependent clotting factors. As a result, clotting occurs at a much slower rate. One good way to think about vitamin K and its importance while taking warfarin (Coumadin) is that you need to maintain a balance between the amount of vitamin K in your body and the amount of warfarin (Coumadin) prescribed by your healthcare provider. Changes in the amount of vitamin K in the diet can alter the metabolism of warfarin (Coumadin ®). However, vitamin K does not influence the action of other blood thinners, such as heparin or low molecular weight heparins (Lovenox ®.
Fragmin ®, or Innohep ®). You should aim to keep the amount of vitamin K in your diet consistent. For example, if you normally eat two servings per day of food that is high in vitamin K content, you should continue this pattern every day. If you do not normally eat foods that are high in vitamin K, do not suddenly eat a large amount of them. There are certain things about vitamin K that you cannot control. For instance, some medications and illnesses (intestinal diseases and/or infections) can lower the amount of vitamin K in your body or change how your liver metabolizes your warfarin. Yes, your INR refers to the international normalized ratio test, a standardized way to measure how your blood is clotting. The lower your INR, the more quickly the blood clots or the “thicker” the blood. The higher your INR, the longer it takes the blood to clot or the “thinner” the blood, putting you at risk for bleeding problems. With an increase in vitamin K , your INR level may drop.
Conversely, a decrease in vitamin K intake may increase the INR. Other things, like medications, antibiotics, and herbal products may also influence your INR. Any time your vitamin K intake changes, it is important to notify your anticoagulation healthcare provider. Some of the circumstances that may apply include if you: You do not have to avoid foods or other products that are high in vitamin K; these foods have many other vitamins and minerals that are part of a healthy diet. The most important thing to remember about vitamin K intake is being consistent as much as possible and communicating any changes that may occur to your anticoagulation healthcare provider. The National Blood Clot Alliance (NBCA) and its Medical and Scientific Advisory Board (MASAB) do not endorse or recommend any commercial products, processes, or services. The views and opinions of authors expressed on the NBCA or MASAB websites or in NBCA or MASAB written materials do not necessarily state or reflect those of NBCA or MASAB, and they may not be used for advertising or product endorsement purposes.