Coumadin is the brand name of a commonly used anticoagulant medication known as warfarin. People with an increased risk of blood clots often take Coumadin to prevent blood clots and related health complications. Coumadin can be a tricky medication to take, and may cause interactions with many types of foods and herbal products, possibly including high-protein diets. Be sure to tell your doctor about any special diets you are following if you are prescribed Coumadin.
High-Protein Diets
Low-carbohydrate, high-protein diets are a popular weight loss plan. Although the effect of high-protein diets on Coumadin have not been rigorously studied, case reports indicate that Coumadin may not work as effectively in certain individuals following a high-protein diet, reports an article published in the April 2005 issue of the medical journal "The Annals of Pharmacotherapy." Additional research is needed to define the exact effect of high-protein diets on Coumadin therapy, as well as the mechanism behind this effect.
Adjusted Dose
The 2005 paper in "The Annals of Pharmacotherapy" described two patients who had been receiving a steady dose of Coumadin for several years. After starting a high-protein, low-carbohydrate diet, both patients had to increase their doses of Coumadin by 20 to 30 percent to maintain the same therapeutic effect. After stopping the high-protein diet, the required dose for both patients returned to the previous level. If you are taking Coumadin and you want to start a high-protein diet, talk to you doctor to arrange additional testing of your Coumadin levels.
Soy Protein
Protein derived from soybeans may reduce the effectiveness of Coumadin, even if you are not following a high-protein diet. One 70-year-old patient on Coumadin experienced a drop in the effectiveness of his Coumadin therapy after drinking soy milk, which contains high levels of soy protein, reports a study published in the December 2002 issue of "The Annals of Pharmacotherapy". When the patient stopped drinking soy milk, the effect on Coumadin disappeared.
Soy and Vitamin K
The reason for the decrease in effectiveness in Coumadin after ingesting soy protein probably relates to the fact that soybeans and soy protein contain high levels of vitamin K, explains the University of California at San Francisco. Coumadin reduces blood-clotting by inhibiting the action of vitamin K, a vital factor in the blood-clotting process. Consuming foods that contain high levels of vitamin K, such as soy protein, can counteract the effect of Coumadin.
References
- "The Annals of Pharmacotherapy"; Effect of Soy Milk on Warfarin Efficacy; J.A. Cmbria-Kiely; December 2002
- "The Annals of Pharmacotherapy"; Decreased Warfarin Effect After Initiation of High-Protein, Low-Carbohydrate Diets; S.J. Beatty et al.; April 2005
- University of California at San Francisco: What is Coumadin?; June 2009
- New York Univerisity Langone Medical Center: Warfarin; August 2010
