Kale and Warfarin

Publication Date: 
Fri, 04/01/2016
By: Alere Staff

Kale is a vitamin-packed veggie that can be added to a variety of different recipes. It has been used as the main green in salads, as pizza topping, mixed in with pasta and even dried into chips. Considered a “superfood,” kale has been shown in a number of studies to be a healthy addition to your diet.1,2

Kale’s History

Kale was first cultivated from wilder varieties by the Greeks and Romans before it spread throughout Europe, eventually finding its way to the tables of both the British Isles and the Americas. Originally referred to as “colewarts”, use of kale was first recorded in the U.S. in 1669.1A few centuries later, kale found itself becoming the center of attention during the second world war in the Dig for Victory campaign in Britain. Kale was labeled as an easy-to-grow vegetable that was full of important nutrients, supplementing the diets of a people that were experiencing rationing. The vegetable was grown in about 1.4 million allotments within Britain during the war and was traditionally served boiled with foods like boiled bacon and potatoes.2

As the war ended, kale faded from people’s diets. People had found that while the vegetable was incredibly healthy, the strong flavor and mushy texture it developed when boiled was unpleasant. Today, over sixty years later, kale is finding new popularity with the development of a sweeter variety. The baby leaf curly kale, while tasting better, is still full of all the health benefits of its more bitter predecessor.2

Kale and Warfarin

Kale, like other green vegetables including spinach and broccoli, is considered a food high in vitamin K. In fact, kale is packed with many vitamins. One cup of kale raw has 206% of the suggested daily amount of vitamin A, 134% percent of the daily vitamin C and 684% of the daily value of vitamin K.1 It is no surprise that one cup of raw kale contains 472.2 micrograms of vitamin K, making it one of the foods higher in vitamin K content.

Despite kale being high in vitamin K, it is still considered an excellent addition if you stay consistent with your diet. Kale is high in antioxidant levels and has been shown to aid in DNA repair, slow the growth of cancer cells and can protect against prostate and colon cancers.1 Kale also has anti-inflammatory capabilities and can help to the prevent of arthritis, heart disease and a variety of autoimmune diseases.1 An excellent source of omega three-fatty acids, kale contains properties that can help regulate blood clotting, build cell membranes in your brain and protect against heart disease and stroke.1

It is also important to note that when cooked, the vitamin K content of kale rises. One cup of kale cooked contains around 1,062.1 micrograms of vitamin K. However, studies have shown that the effectiveness of the several antioxidants and vitamins within the vegetable are reduced when cooked.  

Interested in learning more? Check out this other articles about foods and Vitamin K:


  1. Mercola.com. What is Kale Good For? FoodFacts. 2016. Retrieved from the website:http://foodfacts.mercola.com/kale.html.
  2. Poulter, Sean. World War Two Vegetable Comes Back As ‘Superfood.’ DailyMail.com. 03 October 2007. Retrieved from the website: http://www.dailymail.co.uk/news/article-485506/World-War-Two-vegetable-comes-superfood.html.