Coumadin (warfarin sodium) is a prescription medicine used to treat blood clots and to lower the chance of blood clots forming in the body. Blood clots can cause strokes, heart attacks, or other serious conditions if they form in the legs or lungs, such as deep vein thrombosis or pulmonary embolisms. Coumadin decreases the body’s ability to form blood clots by blocking the formation of vitamin K–dependent clotting factors (substances in the blood that act in a sequence to stop bleeding by forming a clot). Vitamin K is needed to make clotting factors and prevent bleeding.

When it comes to Coumadin and diet, there is no specific “Coumadin/Warfarin diet.” However, what you eat and drink does have the potential to affect how Coumadin works in your body – this includes high amounts of vitamin K, alcohol, and some herbal and dietary supplements, including cranberries and nutritional supplements.

  • Vitamin K- the amount in the diet affects the amount/dose of Coumadin needed. Physicians need to balance medication doses with oral diets to allow the drug to work correctly. Some patients assume they need to eliminate vitamin K containing foods from their diet once they begin taking Coumadin, however a low vitamin K diet is not needed. They key is to consume a moderate amount of foods containing vitamin K in the same amounts from week to week. Eating more or less of these foods may change the way the medication works – too much vitamin K in the diet can lower the effect of Coumadin, but too little can lead to weak bones and other health problems. It is best practice to continue a balanced diet while the correct Coumadin dose is being established by the physician and to moderate the amount of vitamin K consumed daily. It is okay to eat foods that may be considered high in vitamin K, however the total amounts should be limited – for example, it is better to eat a ½ cup serving of vitamin K containing foods each day then to consume three or four cups once or twice a week. Foods that contain high amounts of vitamin K include dark leafy greens (such as spinach, kale, collard/mustard/dandelion/turnip greens), broccoli, Brussel sprouts, romaine lettuce, asparagus, and cabbage (sauerkraut, coleslaw).
  • Cranberries – moderate amounts of cranberry products, such as a glass of juice daily, is acceptable. However patients should avoid consuming large amounts of cranberries, cranberry juice, and cranberry supplements while taking Coumadin.
  • Alcohol – Consuming alcohol is not recommended with Coumadin as more than one to two drink per day can change the way the body uses Coumadin.
  • Dietary and Herbal Supplements – the use of herbs during cooking, such as fresh garlic, is safe while taking Coumadin. Although the use of herbs in tablet/pill form may affect how the body uses Coumadin. It is safe to take a multivitamin that contains vitamin K daily, however some supplements such as Ginseng, CoQ10, Ginger, and Garlic may be contraindicated to use with Coumadin. The use of liquid nutritional supplements/drinks, such as Ensure or Boost, may increase the body’s vitamin K level if multiple bottles are consumed daily and may require a change or increase in dosage.

While on Coumadin/Warfarin regular blood tests are scheduled to review a patient’s PT/INR (to measure how long it takes for the blood to clot). It is important to inform physicians of dietary changes, including the start/end or change in supplement intakes, including both liquids and tablet forms – adjustments in Coumadin dosage may be needed following with dietary changes.