Health and Lifestyle

Vitamin K antagonist therapy and nutrition

Do I have to avoid green vegetables when taking my anticoagulation medicine?

No, not at all. The vitamins and secondary plant substances present in vegetables make them one of the most important types of food to keep the heart healthy. It is all about moderation. Some foods - especially leafy green vegetables - can reduce the effects of your vitamin K antagonist, such as warfarin. These should be consumed in smaller quantities rather than being eliminated from your diet plan.1 Extreme changes to your diet can have a stronger effect on your INR value than eating foods containing vitamin K in a moderate amount.2

For example, a sudden and radical shift from eating only a minimal amount of vegetables to a strict vegetarian or vegan diet can affect blood clotting. If your aim is to shift to a diet with more vegetables you should do so gradually. Mixing two vitamin K-rich ingredients in one meal should also be avoided. You can replace one ingredient to make a meal slightly less burdensome. For example: Eat cucumber salad as a side dish to go with calf’s liver instead of lettuce.


INR: International Normalized Ratio



  1. Healthlink BC. (2009). Article available from [Accessed January 2021]
  2. Lurie et al. (2010). Br J Clin Pharmacol 70, 164–170