Spinach, Vitamin K and Warfarin

Publication Date: 
Fri, 01/01/2016
By: Alere Staff

  Following a healthy diet should be seen as more than just a health trend. According to the American Heart Association (AHA), a healthy diet and lifestyle are your best weapons in the fight against heart disease.1 The AHA recommends an overall healthy dietary pattern that includes a variety of fruits and vegetables. One green vegetable that is considered as part of a healthy diet is spinach.

Spinach is full of important vitamins and minerals our body needs including vitamin A, manganese, folate, magnesium, iron, copper, vitamin B2, vitamin B6, vitamin E, calcium, potassium, vitamin C and, of course, vitamin K.

Warfarin and Vitamin K

Vitamin K is used by your body to produce some of the clotting factors in your blood, helping you to stop bleeding when you are hurt. For a patient who has problems with clots forming unnecessarily and in the wrong places, warfarin works by interfering with how your body uses vitamin K. Vitamin K occurs naturally in many leafy green vegetables like spinach and broccoli and is also produced by the bacteria present in our digestive system.2 If you are a patient on warfarin, the thought of eating a bowl of spinach rich in vitamin K might make you stop and think.

Within your liver, warfarin prevents the production of vitamin K dependent clotting factors, slowing down your body’s ability to clot.2 Changes in the amount of vitamin K that you get from your diet can influence warfarin’s effectiveness within your body. An increase in vitamin K in your diet may cause your INR level to drop while a decrease in vitamin K can increase your INR level.2,3  

Spinach and Vitamin K

Perhaps the most important thing to realize about the connection between vitamin K and warfarin is consistency. Healthy green foods like spinach do not have to be avoided completely. Leafy foods with vitamin K, such as spinach, are not bad for your body.

Spinach contains a large amount of vitamin K. One cup of raw spinach has about 144.9 mcg of vitamin K while a cup of cooked spinach has 888.5 mcg of vitamin K. It is important to maintain the balance between your warfarin dose and your vitamin K intake.2 If you normally eat a serving of spinach every day, you can typically maintain your pattern. Likewise, if you normally don’t eat spinach or leafy greens on a daily basis, be careful about suddenly eating a large amount. Big differences in the amount of these foods can affect your INR.

To keep track of the Vitamin K amounts of all the foods you eat, visit our Vitamin K Finder. If you do decide to change your diet or take supplements, it is always best to consult with your physician first.


  1. AHA. The American Heart Association’s Diet and Lifestyle Recommendations. Aug 12, 2015. Retrieved from the website:http://www.heart.org/HEARTORG/GettingHealthy/NutritionCenter/HealthyEating/The-American-Heart-Associations-Diet-and-Lifestyle-Recommendations_UCM_305855_Article.jsp#.VnhvU03fgdU.
  2. Earl, L. RN, BSN, CACP. Vitamin K and Coumadin – What You Need to Know. National Blood Clot Alliance: Stop the Clot. November 28, 2008. Retrieved from the website:https://www.stoptheclot.org/vitamin-k-and-coumadin-what-you-need-to-know.htm.
  3. NHS. Anticoagulants, Warfarin. NHS Choices. Jun 6, 2014. Retrieved from the website:www.nhs.uk/Conditions/Anticoagulants-warfarin-/.