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The Effect of Folic Acid on Coumadin

author image Jill Corleone, RDN, LD
Jill Corleone is a registered dietitian and health coach who has been writing and lecturing on diet and health for more than 15 years. Her work has been featured on the Huffington Post, Diabetes Self-Management and in the book "Noninvasive Mechanical Ventilation," edited by John R. Bach, M.D. Corleone holds a Bachelor of Science in nutrition.
The Effect of Folic Acid on Coumadin
A caserole made with beans and sausage sits on a wooden table. Photo Credit AlexPro9500/iStock/Getty Images

When taking Coumadin, you need to be careful about some of your food choices. Foods high in vitamin K, such as kale and spinach, can decrease the medication's effectiveness. You may also need to be careful about what vitamins you take on Coumadin. Taking the B vitamin folic acid while you are on Coumadin increases metabolism, which may affect your dosage needs.


Coumadin, generically known as warfarin, is a blood thinner prescribed to prevent heart attacks and strokes. It helps prevent blood clots from forming by blocking some of the blood clotting factors in your body. Coumadin increases your risk of bleeding and should only be taken under the close supervision of a doctor. You should not take Coumadin if you are pregnant, have blood in your urine or stool, a bleeding stomach ulcer or an upcoming surgical procedure or spinal tap.

Folic Acid

Folic acid is a water-soluble B vitamin. It plays an important role in the production and maintenance of new cells and is especially important during periods of rapid growth, such as pregnancy and infancy. Folic acid is also necessary for the proper formation of red blood cells, and adequate intakes help prevent anemia. The recommended dietary allowances for adults for folic acid is 400 micrograms a day. Good food sources include fortified breakfast cereals, beef liver, spinach, great northern beans and asparagus.

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Coumadin and Folic Acid

A 2010 study published in "Clinical Therapeutics" investigated whether folic acid supplementation increases the dosage requirement for warfarin. The prospective study included folic-acid-deficient individuals supplemented with folic acid who were on long-term stable doses of warfarin. The participants were monitored before starting the folic acid supplementation, with followup at 30 and 60 days. The study found a significant increase in the metabolite responsible for clearing warfarin, but there were no significant changes in warfarin dosage or international normalized ratio, also known as INR.


While folic acid supplementation appears to affect the metabolism of Coumadin, it does not affect how the medication works or your dosage. In fact, neither peer-reviewed medical information website Drugs.com or the U.S. National Library of Medicine warn against supplementing your diet with folic acid while on Coumadin. However, keep your doctor informed of all medications and vitamin, mineral and herbal supplements you take when prescribed Coumadin.

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