Sushi and Warfarin

Publication Date: 
Sun, 11/01/2015
By: Alere Staff

  A Japanese staple, sushi is a dish with worldwide popularity. As early as the fourth century, a reference in a Chinese dictionary mentions salted fish being placed in rice. This concept of sushi was likely introduced around the ninth century in Japan and, over the next seven centuries, evolved into a delicacy available only to the upper class. From the 1600’s to the 1800’s, the process of making sushi changed to a quicker method in Tokyo’s Edo period.

Then in the 1920’s, Hanaya Yohei began selling modern nigiri sushi. As advances in refrigeration were made, this sushi, as well as others, became accessible worldwide.1

The popularity of sushi has been growing in the United States since it was first introduced in the Los Angeles area in 1966 by a man named Noritoshi Kanai and his business partner, Harry Wolff. From there, several sushi bars opened in Chicago and New York before spreading all over the United States.1 Sushi has been constantly evolving since that time and now ranges from the traditional nigiri sushi to rolls wrapped in seaweed or soy paper. Due to the great variety in sushi, it is important to know the specific ingredients you are eating if you are a patient on warfarin. Some sushi ingredients are high in Vitamin K and could affect your INR levels.

What’s Inside Matters

As previously mentioned, sushi rolls are often wrapped in seaweed with the most commonly used being nori, a dried layer of seaweed pressed into thin sheets. Ten sheets of nori contain only one (1) microgram of vitamin K and is considered relatively safe to eat for the warfarin patient.2 When it comes to sushi and warfarin, it’s what’s inside that matters most. Ingredients inside the wrapper may include rice, avocado, cucumber, mushrooms, carrots, radishes, ginger, scallops, eel, sea bass, lobster, trout and bluefish. Ingredients that are higher in fish oils, like salmon and bluefish, can also contribute to changes in your INR. An intake of 5.5 ounces of fresh fish daily is roughly equivalent to the consumption of 1,000 milligrams of fish oil daily in the amount of EPA and DHA that the body absorbs.3 A typical sushi roll contains 3 ounces of fish, while nigiri is typically 1 ounce for each piece. Documented cases show a rise from an INR of 2.8 to 4.3 with an additional 1,000 milligrams of fish oil a day over a one month period.4 It is always a good idea to discuss diet and supplements with your doctor.

Even though sushi is associated with fish, the list of ingredients is endless and includes almost anything locally available to the chef. As we know, many vegetables, especially greens, are high in vitamin K so it is always good to know the exact ingredients in the sushi you are eating.

For more information on the vitamin K content in the foods you are eating, check out our Vitamin K Finder.


  1. Avey,Tori. Discover the History of Sushi. PBS Food: The History Kitchen. September 5, 2012. Retrieved from website:
  2. Harlan, T.S. MD, FACP. How Much Vitamin K is in Nori (The Seaweed Used to Wrap Sushi)? Ask Dr. Gourmet. 2015. Retrieved from website:
  3. Kresser, Chris. The Fish vs. Fish Oil Smackdown. Retrieved from 2015.
  4. Buckley, MS et al. Fish Oil Interaction with Warfarin. Retrieved from Jan. 2004; 38(1):50-2.