Tehran University of Medical Sciences Journal of Pharmaceutical Care 2322-4630 3 1-2 2016 05 30 3 6 EN Mona Foroughi Faculty of Nutrition Sciences and Food Technology, Department of Clinical Nutrition and Dietetics, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Reza Miri Imam Hussein Hospital, Department of Cardiology, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Farhad Assarzadegan Imam Hossein Hospital, Department of Neurology, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Javad Nasrollahzadeh National Nutrition and Food Technology Research Institute, Faculty of Nutrition Sciences and Food Technology, Department of Clinical Nutrition and Dietetics, Shahid Beheshti University of Medical Sciences, Tehran, Iran. 2016 05 28 Background: Warfarin is an effective oral anticoagulant which exert its effect by blocking the utilization of vitamin K. Warfarin therapy requires ongoing monitoring using the international normalized ratio (INR). In this study, effect of modest increase in vitamin K intake from vegetables on INR values was evaluated in warfarin treated patients. Methods: A single-center study involving 24 outpatients (mean age, 62 years) with two last INR in therapeutic range in which INR variations was less than 0.5. Patients were selected based on their VKORC1 1639G→A polymorphism so that 8 patients from each of GG, AA or GA genotypes were recruited. Patients were asked to consume a vegetable mix (including lettuce, peeled cucumber and tomato) containing approximately 100 µg vitamin K (divided in two meals, lunch and dinner) daily for one week when INR response was measured. Results: Daily consumption of vegetable mix decreased patient’s INR from 2.43±0.51 to 2.08± 0.46 (P<0.001). INR value had a significant decrease in each VKORC1 genotypes (from 2.55± 0.55 to 2.21± 0.54 in GG, 2.35± 0.33 to 2.00± 0.25 in AA, and  2.39± 0.65 to 2.00± 0.25 in GA) but the values did not differ between genotypes. Conclusions: Daily increase in vegetable salad containing approximately 100 µg, decreased INR of patients. Therefore, avoiding variation in consumption of foods with even moderate content of vitamin K could help to prevent INR fluctuations in warfarin treated patients. https://jpc.tums.ac.ir/index.php/jpc/article/view/87 https://jpc.tums.ac.ir/index.php/jpc/article/download/87/80