Warfarin: Vitamin K and beyond

摘要

At the Toronto Rehabilitation Institute, mpatients usually maintain acceptable INRs (international normalized ratio - blood clotting time). However, patients managing their diets at home often require some guidance. We therefore developed a handout, What You Need To Know About Food When You Take Warfarin, to provide patients with printed information that would be easy to use, and as current and concise as possible.Information was gathered from articles, existing handouts, vitamin K tables and booklets from drug companies. Several challenges emerged. Vitamin K values appeared to be still in development, and there were variations and gaps in information, For example, natto, a Japanese fermented soy item, was included in at least one source as "very high - avoid", but no actual value was found in any of the information collected. Nutrition factors other than vitamin K were identified, with varying types of advice and degrees of evidence. Liaising with the pharmacy department was invaluable. Their resources indicated that many medications and herbals affect warfarin action. Although our focus was on food, we included advice for patients to check all medications and changes with their doctor and/ or pharmacist. The following summary lists the information and decisions made for the handout.