Folic acid is a B vitamin. Warfarin is a medication used to prevent and treat blood clots that can form in deep venous thrombosis, and as a result of pulmonary embolism, a heart condition called atrial fibrillation, recurring heart attacks, strokes and replacement of heart valves. You must be careful with your diet while taking warfarin, but there is no interaction between warfarin and folic acid.
Warfarin
Warfarin, an anticoagulant medication, also goes by the name of coumadin, and is the most used oral anti-coagulant, according to David Slattery, M.D., in “Tintinalli’s Emergency Medicine.” It prevents blood clots because it interferes on a biochemical level with proteins necessary for clot formation. Warfarin prevents vitamin K from becoming active; K is a vitamin that proteins named Factors II, VII, IX and X must have to change to their active forms. Vitamin K also interferes with production of protein C and protein S; all these proteins are involved in clot formation.
Folic Acid
Vitamin B-9 is also called folate; folic acid is the synthetic or manufactured form of folate, taken as a supplement. Folic acid has been added to many cereals and breads. Folate is naturally found in most food, but especially in dark green, leafy vegetables, yeast, nuts and liver. Cells use this vitamin for normal development of the nervous system and the brain, to make DNA and RNA, to make red blood cells, and to allow red blood cells to mature, explains Elizabeth Corwin in “Handbook of Pathophysiology.”
Warfarin and Your Diet
Since warfarin interferes with activation of vitamin K to stop clots from forming, the only dietary restriction is to not consume food that is rich in vitamin K. Consuming a lot of vitamin K, or taking a lot of vitamin K supplements, would work against warfarin and make the medication less effective, as explained in “Williams Hematology” by Charles Francis, M.D. If warfarin is less effective, you will be more likely to form blood clots. While vitamin E may increase the anti-coagulant effect of warfarin, taking a large amount of folic acid has no effect.
National Institutes of Health Recommendations
The National Institutes of Health lists dietary restrictions you must follow when you take warfarin. It does not warn about any interaction between consuming a large amount of folic acid and taking warfarin, but warns that you must pay attention to the amount of food you eat that has vitamin K and that you are consistent in the amount of vitamin K you eat every day. Do not consume more than one serving of vitamin K-enriched food each day. Dark green, leafy vegetables have the highest amount of vitamin K, so it is best not to eat more than one-half cup of mustard greens, collards, spinach, turnip greens or kale every day.
References
- “Basic & Clinical Pharmacology”; Bertram Katzung, M.D., Ph.D., Susan Masters, Ph.D. et al.; 2009
- “Handbook of Pathophysiology”; Elizabeth Corwin, MSN, Ph.D., FNP; 2000
- National Institutes of Health: Coumadin and Vitamin K
- “Tintinalli’s Emergency Medicine: A Comprehensive Study Guide”; Judith Tintinalli, M.D. et al.; 2004
- “Williams Hematology”; Marshall Lichtman, M.D., Thomas Kipps, M.D. et al.; 2010
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