Even though you are on coumadin you can still eat the green leafy veggies. I know a lady who is on it and is a vegetarian. She just adjusts her coumadin levels so that she can eat. I will have to ask my mom if you are supposed to increase or decrease the dosage. She would do that for my grandma who has been on it for years. This veggi lady I know taught my mom the sliding scale for the coumadin dosage. (She did discuss this with my grandmas docs, which I would suggest you do also)