Did you ever wonder why your physician or health care professional put you on a medication called Coumadin or another name it’s sometimes called, Warfarin? Well, here are the answers to your questions, and more. My colleague, friend and mentor, Dr. Nancy Collins, shared this on her website, and I am sharing with you too, which is very important-- if you, or loved one, or someone you know takes this medication.
Your Right to Know the Answers
Drug-Nutrient Interactions with Coumadin
I just started taking Coumadin and was told I need to watch my diet. Why?
Coumadin is a medicine for people who are at an increased risk for harmful blood clots that can block the flow of blood to the heart or brain. Vitamin K is a vitamin that is needed for blood clotting to occur. That’s why vitamin K is the main nutrient that you need to pay attention to when you are taking Coumadin. Sudden changes in the vitamin K in your diet may affect how your Coumadin works and whether or not your body forms blood clots.
Why do I have to have my blood tested so much when I am taking Coumadin?
Coumadin is prescribed to prolong the time it takes blood clots to form. Your doctor will draw your blood often to test for your INR (International Normalized Ratio) and PT (Prothrombin Time). These tests measure how long it takes for blood clots to form and tells your doctor if you are taking the right amount of Coumadin.
What might happen if I eat too much vitamin K?
Too much vitamin K in your diet can decrease the effect of your Coumadin and result in blood clots. While there are many other things that can affect blood coagulation (certain medications, alcohol, and some medical conditions), watching your intake of vitamin K is one way to help make sure the Coumadin your doctor prescribed in working the way it was intended.
How much vitamin K can I have each day?
Rather than focus on how much vitamin K you should eat, experts say it is more important to keep your vitamin K intake consistent from day to day. It is suggested that you limit your intake of high vitamin K foods to no more than one serving each day, and limit intake of foods “moderately high” in Vitamin K to no more than 3 servings daily. It is also important not to have drastic changes in your vitamin K intake from day to day. For example, if you eat 3 cups of a high-vitamin K food like spinach one day and none the next, this can affect the way your Coumadin works.
What foods are high in Vitamin K?
It is suggested that you eat no more than 1 serving daily of these foods that are high in vitamin K: One half cup of cooked kale, cooked spinach, cooked turnip greens, cooked collards, cooked Swiss chard, and cooked mustard greens and ¼ cup raw parsley.
It is suggested that you eat no more than 3 servings daily of these foods that are moderately-high in vitamin K: One half cup cooked Brussels sprouts, one cup raw spinach, raw turnip greens, shredded leaf lettuce, raw broccoli, raw endive lettuce, and raw romaine lettuce.
Are there any other things that can interact with my Coumadin dose?
Yes. Alcohol (greater than 3 drinks per day) can increase the effect of Coumadin. Talk to your doctor about how much alcohol you drink and whether or not it can affect your blood clotting.
Many over-the counter dietary supplements, including ginger, garlic, ginko, and vitamin E, can effect blood clotting. It is best not to take any vitamin or herbal supplement, including Vitamin E, when you are taking Coumadin. Be sure to discuss any herbs, vitamins, supplements, and other medications that you are taking with your doctor or pharmacist before taking Coumadin.
1. ADA Nutrition Care Manual. Available to subscribers at www.nutritioncaremanual.org. Accessed August 2007.
2. Warren Grant Magnuson Clinical Center, National Institutes of Health, Drug Nutrient Interactions Task Force. Important information to know when you are taking Coumadin and Vitamin K. Available at http://ods.od.nih.gov/factsheets/cc/coumadin1.pdf. Accessed August 2007.
3. Nancy Collins, PhD, RD, LD/N, FAPWCA. RD411 .
Thank you for reading!