 [ Symptoms ] what foods should be avoided when taking coumadin warfarin [ Disease ] there really are not any foods you need to avoid while taking coumadin since coumadin works on vitamin k foods that are high in vitamin k can affect your inr the test to measure how well your coumadin is working foods like kale spinach collard greens and brussels sprouts all have high amounts of vitamin k while you should not binge on them one day and avoid them the next if you have one or two servings a week consistently you should not notice a difference