Warfarin: You can have your leafy greens and eat them too!

Warfarin:  You can have your leafy greens and eat them too!

Have you heard your health provider say, “Avoid dark leafy greens”? Or have you seen a medication label that read, “Do not consume grapefruit”? These are discouraging messages when these may be food you love. The good news is that you can still enjoy these foods!


Warfarin is a blood thinner and Vitamin K does the opposite of this drug by helping blood to clot. So eating more Vitamin K rich foods than usual could decrease the blood thinning effects of warfarin while eating less vitamin K could increase the blood thinning effects.1 The important thing to remember is eat Vitamin K consistently and moderately. Foods high in Vitamin K, like dark green vegetables, should be enjoyed as a part of a balanced diet. Take a look at the handout provided to see which foods have high amounts of vitamin K and those that have less. Keeping the amounts of vitamin K relatively consistent from day to day allows for you to find the dose of warfarin that is right for you and your diet without interfering with the drug’s effect. 2

Grapefruit has also been a concern with warfarin because certain components found in grapefruits and grapefruit juice stops the break down of warfarin so grapefruit may have the potential to hinder the benefits of your medication but typically in large amounts. 3 Ultimately, grapefruit is of little concern for interacting with Warfarin.4 So feel free to enjoy half a grapefruit or small glass of grapefruit juice.

Handout: Food_Interactions_with_Warfarin

Guest Blogger:  Tara Hubbard


1.  Pronsky, Zaneta M., MS, RD, LDN, FADA. Food- Medication Interactions. Ed. 15. 2008. Pg 320-32

2.Booth, Sarah Ph.D., and Centurelli, Maria, Pharm. D. Vitamin K: A Practical Guide to the Dietary Management of Patients on Warfarin Volume 57, Issue 9, Article first published online: 27 APR 2009. http://onlinelibrary.wiley.com/doi/10.1111/j.1753-4887.1999.tb01815.x/pdf.

3. Runkel M, Tegtmeier M, Legrum W. Metabolic and analytical interactions of grapefruit juice and 1,2-benzophyrone (coumarin) in man. Eur J Clin Pharmacol. 1996;50:225-230.

4. Pronsky, Zaneta M., MS, RD, LDN, FADA. Food-Medication Interactions. Ed. 14. 2006.



1.    KCBY-TV, 3451 Broadway, North Bend, OR 97459


2. http://www.nlm.nih.gov/medlineplus/ency/imagepages/18116.htm






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