Coumadin is used universally to prevent and treat venous thrombosis and pulmonary embolism and to prevent complications after myocardial infarction. Patients who take Coumadin must have their blood tested for INR in order to maintain the proper level of anticoagulation. Often times physicians will tell their patients NOT to eat green leafy vegetables and olive oil because the high concentration of vitamin K can lower the INR and counteract the effects of Coumadin. This recommendation is inappropriate for two reasons.
First, by restricting green leafy vegetables and olive oil you lose the cardiovascular protective effect that these foods provide. And it is usually people on Coumadin that need this beneficial effects. Secondly, a study found that high levels of vitamin K found in these foods help to stabilize the INR fluctuations that is so often seen in patients.
So the best advice for people on Coumadin is to maintain a consistent intake of foods that are high in vitamin K.