Clam Chowder and Warfarin

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

Clam chowder is a familiar dish to many Americans. Hailing from the east coast, clam chowder is considered by many to be a comfort food. Served warm, these soups are ideal for cold afternoons or evenings. Regional varieties of clam chowder have different recipes and a different dedicated group of supporters.1 As a patient on warfarin, you are always on the lookout for foods that may affect the results of your INR values more than most. 

The three popular types of clam chowder that we looked at concerning vitamin K content were New England clam chowder, Manhattan clam chowder and the growing popular Long Island clam chowder.

What is Chowder?

In the past, a simple dish of chowder was considered a “poor man’s food”, mostly because it was a thick soup made from available foods, salted pork and thick ship biscuits.1 Vegetables and fish were stewed in a cauldron-like pot, somehow giving the soup the term “chowder” in English-speaking nations. Some sort of fish stew is a common food in every nation near an ocean, with the type of fish used being the name for the chowder.These old fish stews eventually led to the clam chowder known today. The first and oldest-known printed fish chowder recipe in America was in the Boston Evening Post on September 23, 1751.1

Since those original chowders, the recipes have grown and varied. For example, no longer do we use those thick ship biscuits in our New England clam chowder. Instead, more cream or milk is added. Typically, chowders are served with a sprinkling of oyster crackers on top or served in a bread bowl. Around 1939, tomatoes were added to clam chowder in place of cream, leaving some people loyal to the original chowder appalled. At one point, a bill was even introduced in legislature that made it illegal to add tomatoes to clam chowder. Lucky for those who are in favor of tomato infused chowder, the bill did not pass and the chowder was given the title Manhattan clam chowder instead.1 However, variations have led to several different chowders with different ingredients and different levels of vitamin K.

Clam Chowder and Warfarin

Lucky for patients on warfarin, both New England clam chowder and Manhattan clam chowder are considered low in vitamin K. The basic ingredients of New England clam chowder include clams, bacon, cooked onion, red potatoes and cream, all of which are considered low in vitamin K.2 Manhattan clam chowder has many of the same basic ingredients with the addition of tomatoes or tomato product.3 When enjoying a bowl of either chowder, the only ingredients to be aware of are the additions of celery and specific spices or garnishes including parsley, bay leaves, oregano leaves and thyme. All of these can contain higher levels of vitamin K and, depending on how much is included in the recipe, may affect your INR level.

If you don’t want to start from scratch and cook your own chowder recipe, there are different companies that offer their New England or Manhattan chowder recipes in cans of condensed soups. Both types of chowder have shown to be low in vitamin K when canned although it is always a good idea to check the ingredients label of any soup you eat.

A clam chowder that is starting to gain popularity in groups along the east coast is the pinkish Long Island clam chowder, a mix of half New England white chowder and half Manhattan red chowder.4 The two chowders used in Long Island clam chowder are low in vitamin K, so you can imagine the result would be low as well. Just like with the others, it is important to check the ingredients or garnishes as sometimes new vegetables or spices can be included that may have more of an effect on your INR level.

So for a bowl of comfort, consider indulging in this delicious fish chowder. Luckily for warfarin patients, the tiny little oyster crackers included and the sourdough bread used in bread bowls are both considered low in vitamin K and will bring extra comfort to the warmth.


  1. Stradley, Linda. History of Chowder. What’s Cooking America. 2004. Retrieved from the website:
  2. Yankee Magazine. Classic New England Clam Chowder. Yankee. September 24, 2010. Retrieved from the website:
  3. Lagasse, Emeril. Manhattan Clam Chowder. The Food Network. 2001. Retrieved from the website:
  4. Bolder, Timothy. Long Island Clam Chowder: Secret Blend Slowly Catching On. Long Island Press. September 4, 2013. Retrieved from the website: