February 24, 2013 by Robin
As a physician, I’ve spent years educating patients on how to maintain a stable INR while on warfarin (Coumadin). As a patient, I’ve discovered there is a lot more to it than I ever realized.
My first hint this might be more complicated than avoiding kale and spinach was when my massage therapist mentioned that her mom threw off her INR by indulging in hummus. Hummus? But that’s not green.
My next discovery was that there is lots of conflicting information out there. One medical center’s vitamin K handout will consider something to be high in vitamin K and another will consider it low in vitamin K. What gives?
Part of it is serving size. A spring of parsley or basil is fine, but pesto is way too much. Garbanzo beans are fine but a reasonable amount of hummus (and when I say reasonable, I mean a lot because I love hummus…especially the hummus from the middle eastern restaurant just a couple blocks from our house) can contain enough vitamin K to throw off your INR (especially if it’s made with an oil that is high in vitamin K and some fresh herbs). Peas officially have a medium amount of vitamin K but for someone like me who will eat two cups at a sitting, it can have an effect.
On the other hand, some serving sizes are out of proportion in the other direction. The 150 micrograms of vitamin K in canola oil seems like a lot…until you see that it takes 7 tablespoons to get that much. Merely using canola oil in the bottom of the pan for scrambled eggs won’t hurt you.
Here are my favorite resources of determining the vitamin K content of foods:
From the National Institute of Health (contains info on supplements as well)
And here are some thoughts on following the diet:
* If you are only going to be on warfarin a short while (say 3-6 months), the easiest thing is to just avoid vitamin K entirely. I’ve seen people who had to have their INR checked and warfarin dose adjusted every 1-2 weeks for the entire 3-6 months they were on warfarin. Besides being a nuisance to go to the doctor all the time, the fluctuations mean you may not be in a safe range much of the time.
* If you are going to be on warfarin long term, ask your doctor to help you get vitamin K containing foods back in your diet. The way I’ve done it with others in the past is to first bring their INR up to the high end of the therapeutic range while they continued on their low-vitamin K diet. They then added in vitamin K containing foods, carefully measuring amounts to make sure they were eating the same amount of vitamin K every day. We rechecked their INR every 3-4 days during this period. This is not something to try unless you are really conscientious and your doctor is comfortable doing it. Many, many doctors are NOT comfortable doing this. It’s risky because it takes so much careful planning and if you mess up, the potential complications are enormous.
And on that cheerful note, go forth and have a stable INR!
What tips do you have for life on warfarin?