Patients taking warfarin often have questions related to eating green leafy vegetables. Well-meaning family members, friends, and health care providers may tell them that they should avoid foods high in vitamin K (generally, green leafy vegetables and some oils). Adopting this advice, however, may make stabilization of the international normalized ratio (INR) difficult.
If a patient has a diet that is very low in vitamin K intake, any increase in green leafy vegetables represents a large percentage increase in vitamin K, and a large drop in the INR. Patients with diets already high in vitamin K who increase their intake of green leafy vegetables will have a much lower percentage increase.
Dr. Garrett is a clinical pharmacist practitioner at Cornerstone Health Care in High Point, NC.