Requirement for Blood Thinners - Vitamin K

Information, Diet Suggestions, and Resources

Requirement for Blood Thinners-Vitamin K

There are many conditions that require individuals to be on a medication called Coumadin (also called Warfarin), a therapy that makes the blood clot less easily or “thins” the blood. A history of heart attack, stroke, pulmonary embolism, deep vein thrombosis, as well as several heart conditions may require individuals to take this medication or other medications that affect the clotting of the blood.

One thing to consider if on Coumadin is that Vitamin K is the antidote to this  medication. This means that vitamin K counteracts the effects of Coumadin and makes it less effective (thus allowing the blood to clot faster). Therefore, if you are taking Coumadin or other blood thinners, avoid foods that are high in vitamin K.

The Diet

While on blood thinners your blood will be checked regularly to ensure that the  current amount of Coumadin being taken is not too little (“blood is too thick”) or too great (“blood is too thin”). This means that instead of simply limiting foods rich in vitamin K, it is recommended to simply stay consistent with the vitamin K that is being ingested. Do not go overboard with vitamin K rich foods one week and then eat none the rest. Be mindful. You should also avoid grapefruits and grapefruit juice as this may interfere with the Warfarin.

Examples of foods rich in vitamin K that you should limit or avoid while on blood thinners include spinach, green beans, kale, eggplant, collard greens and broccoli. In addition, do not take supplements that contain large amounts of vitamin K (more than 100 micrograms/day), such as some calcium supplements.


For additional resources on the relationship between Blood Thinners/Coumadin and Vitamin K and recommended diets while on Coumadin go to: