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Veggies not off-limits when taking blood thinners
Veggies not off-limits to those on blood thinners

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Date published: 4/26/2009

IKEEP HEARING from readers lamenting that they can't eat green vegetables because of the medication they're taking. They've been misinformed.

Americans filled about 30 million prescriptions for the drug Coumadin, also called warfarin, in 2004, according to the Warfarin Institute of America. This medicine helps prevent unwanted blood clots called deep vein thromboses and pulmonary embolisms.

Vitamin K, found in foods such as broccoli and spinach, decreases the effects of warfarin, and this makes many people taking the drug think they can't eat green vegetables at all.

Obviously, blood clots are a serious problem--the NBC journalist David Bloom died of a clot at age 40. And if you are on warfarin, you should talk to your health care provider about your diet. This column is no substitute for personal advice from a doctor or pharmacist.

But, don't give up your veggies. In fact, eating more vegetables and fish, and less red and processed meat, is linked with having fewer clots. That's according to a letter from acting U.S. Surgeon General Steven Galson, published in this month's Journal of the American Dietetic Association.

It's true that large amounts of vitamin K, found in leafy green vegetables, can interfere with warfarin and increase the risk of clots. But it's not necessary to avoid these foods entirely, according to a statement in the American Heart Association's journal, Circulation.

"However, it is important to try to keep the amount of vitamin K you eat consistent" each week, the statement says.

Sudden changes in your vitamin K intake can be a problem. But you can keep the amount steady by eating consistent amounts of leafy green vegetables.


It may also be helpful to know that some green veggies are low in vitamin K. While most vitamin-K-rich foods are green, not all green foods have the same amount of vitamin K.

For example, these green vegetables are relatively low in vitamin K, having less than 100 micrograms per serving: peas, green beans, celery, iceberg lettuce and green peppers.

Vegetables with moderate amount of vitamin K, 100 to 300 micrograms, include asparagus, broccoli, brussels sprouts, green cabbage, endive, green onions, Romaine lettuce, green leaf lettuce and parsley.

Dark green leafy veggies, such as spinach, kale, collard greens and must-ard greens, have the most vitamin K, more than 1,000 micrograms per serving.

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Jennifer Motl is a registered dietitian. Formerly of Fredericksburg, she now lives in Wisconsin.