Warfarin (Coumadin) prevents blood clots by blocking vitamin K. Vegetables supply vitamin K, so some doctors worry that they will interfere with this anticlotting effect.
If you take warfarin, talk with your doctor. The answer may not be to avoid vegetables but simply to keep the amount you eat more or less steady from day to day. That way the blood tests used to set your warfarin dose will stay stable and your doctor will have an easy time setting the dose that is right for you. 1.
1. Barnard, Neal. Power Foods For the Brain.New York: Grand Central Life & Style, 2013.