People who are taking Coumadin need to avoid eating foods with large amounts of vitamin K, according to the Bristol-Myers Squibb Coumadin website. This includes green leafy vegetables because too much of the vitamin reduces the effectiveness of the medicine.
Coumadin is used to prevent and treat blood clots in the lungs and legs as well as those caused by an irregular heartbeat or heart valve problem. By thinning the blood, Coumadin reduces the likelihood of a clot occurring. However, vitamin K is a natural clotting agent, and people who eat foods containing it can counteract the effects of the medicine.
Some foods high in vitamin K include kale, Brussels sprouts, spinach, parsley, chard, collard greens and mustard greens. Some beverages also contain higher amounts of vitamin K, including green tea, cranberry juice and some types of alcohol. People taking Coumadin should try to limit their intake of these foods and beverages when on the medicine.
Adult men should consume no more than 120 micrograms of vitamin K each day, and for women that number is 90 micrograms. However, people using Coumadin may need to adjust those numbers. The best way to determine what to eat and what not to eat is to consult with a doctor, who can come up with a plan tailored to the patient"s needs.