Is it okay to cook with garlic while on Coumadin (warfarin)?

My husband just turned 50 and was surprised with a heart attack. A blood clot was also found in the left ventricle and they are in the process of trying to regulate his Coumadin levels. I can't believe any of this. Anyway, I am trying to fit all the pieces of the puzzle together and thank God I found your website. It is so helpful and easy to get around.

My questions have to do with the diet a person on Coumadin has to maintain. We were told in the hospital that he must avoid garlic, and basically to limit "greens" to small quantities. I always mince garlic when I cook, therefore, we ingest it. But would it be okay to cook with garlic, leaving the clove whole and removing it before eating? Also, parsley is not good for a coumadin patient, but what about other green spices - basil or cilantro - does the same apply? Lastly, green peppers are a no-no, what about red or yellow peppers - does the same hold true?

I thank you in advance for all your help in this. I never would have thought that I would have to be thinking of these things so soon.

The Health meets Food Team Says...

There have been isolated reports in the literature of bleeding after operations in people who were taking high doses of garlic supplements. Such supplements have been shown to exert an effect on platelets (the cells that help blood to clot). That said, there was no actual proof in these case reports that it was garlic that caused bleeding issues. There is a research study published that does show aged garlic extract (AGE) to be safe for users of warfarin. Garlic contains no Vitamin K and there should not be an interaction with warfarin as a result. Garlic in cooking is fine - especially in the low doses that most people will use in their recipes.

Interestingly, many authentic Italian recipes use garlic in the way that you mention. Instead of mincing the garlic it is added as whole cloves and the cloves are not eaten. If using garlic concerns you, this may be an alternative for your cooking with some recipes.

You can find the three lists on this website that give increasing levels of detail about the Vitamin K content of some common foods.

Brief : A short list of commonly-used foods with their relative Vitamin K levels (Low, Medium, High)
Medium : A much longer list of foods, with their relative Vitamin K levels (Low, Medium, High)
Extensive : The same longer list as the Medium document, but with exact levels of Vitamin K in mcgs.

Parsley is on the list as being high in Vitamin K and is something to avoid, as even a tablespoon contains 62 mcg, which is a lot. If one is eating a consistent amount of greens each day, the parsley should be considered the high Vitamin K green for the day. It's best to avoid side dishes with other greens. For instance, don't combine a Caesar Salad with Fettucine Alfredo that contains parsley. Or leave the parsley out of a recipe if you feel that it is not critical to the flavor of the dish.

A tablespoon of cilantro, on the other hand, has only 3.6 micrograms (mcg) of Vitamin K. Basil has a moderate amount at 11 mcg per tablespoon for fresh and 12 mcg for dried (dried and fresh are two completely different flavors, in our opinion). These could be used but not in amounts much higher than noted.

A half cup of green peppers is actually pretty low in Vitamin K at 3.4 mcg, while red peppers have slightly more at 7.7 mcg for the same half cup chopped. Yellow peppers have no Vitamin K as reported by the USDA database. All of these would be safe.