Can you eat kale when taking warfarin?

In this article we are going to answer can you eat kale when taking warfarin, what is kale, is it healthy to eat kale, what is warfarin, what happens if you eat kale when taking warfarin, and what food you should avoid if taking warfarin. 

Can you eat kale when taking warfarin?

Raw kale can be eaten when taking warfarin but it is not recommended to eat cooked or boiled kale because vitamin K content is higher in cooked kale. The recommendation is to moderate your intake of high vitamin K food. 

Men should ingest not more than 120 micrograms of vitamin K per day while women should not eat more than 90 micrograms of vitamin K per day. 

What is kale?

Kale or also known as leaf cabbage and is part of a group of cabbage. Kale plants have green or purple leaves and do not have a central head like other cabbage. Kale grows annually from seeds with a range of germination temperatures. It can survive as low as -15 C. 

There are several kale varieties depending on the leaf types. They might range in color from light green to dark green, violet-green, or violet-brown. 

  • Curly leaf
  • Bumpy-leaf is also known as Tuscan Cabbage
  • Plain-leaf
  • Leaf and spear or feathery type leaf
  • Ornamental, there are many varieties that are not as palatable. They can be white, red-pink, lavender-blue, or violet. 
  • Chinese kale

Kale grows perfectly in the winter. There is a variety of kale called hungry gap that grows after the winter period. There is also another variety that is called Jersey kale or cow cabbage.

Is it healthy to eat kale?

Yes, kale is healthy to eat. Raw kale is composed of up to 84% of water, 9% carbohydrates, 4% protein, and 1% fat. In 100 grams of kale, there are 50 calories, 8.8 grams of carbohydrates of which 3.6 are from fiber, 1 gram of fat, and 4.3 grams of protein.

Based on the daily value percentage of a 2,000 calorie diet, 100 grams of kale can give up to 145% of vitamin C and 371% of vitamin K. Kale also contains enough amounts of folate, vitamin b 6, manganese, magnesium, iron, calcium, and potassium. 

When kale is cooked it provides fewer calories. 100 grams of cooked kale contains 28 calories, 6 grams of carbohydrates, 0.4 grams of fat, and 1.9 grams of protein. Vitamin K is higher with 418 ug, up to 400% of DV, and vitamin C is reduced to 41 mg or 49% of DV. 

What is warfarin?

Warfarin is a blood thinner prescribed by doctors for people that have a higher risk of blood clots or have a blood clot near the heart that could trigger stroke, heart attack, or organ damage.

It works by slowing the clotting factors the body produces by using vitamin K. It has been proven that vitamin K reduces the effectiveness of warfarin. The same action that prevents blood clotting can result in bleeding, that is why is very important to have control over:

  • Incorrect use of drugs
  • Use of certain medications or supplements
  • Diet changes
  • Illnesses

What happens if you eat kale when taking warfarin?

Warfarin is the most used blood thinner and works by blocking vitamin K-dependent steps in the clotting cascade. Warfarin works by decreasing the vitamin K total amount in your body. 

Without enough vitamin K, the vitamin K-dependent clotting factor can’t make your blood clot correctly. So, the best way to help warfarin to work correctly is to maintain a low intake of vitamin K in your food. 

What food should you avoid when taking warfarin?

Warfarin interacts with vitamin K. Small amounts of vitamin K do not affect how warfarin works but it is recommended to not ingest food that contains high amounts of vitamin K.

You should avoid 

  • Kale, especially if cooked.
  • Spinach
  • Brussels sprouts
  • Collards
  • Mustard Greens
  • Chard
  • Broccoli
  • Asparagus
  • Green tea

You should also avoid alcohol and cranberry juice because they increase the effect of warfarin. 

There has also been a link between quercetin and warfarin in clinical studies. Quercetin is a plant pigment that is known as a flavonoid or antioxidant.

Warfarin binds to a protein known as Human Serum Albumin (HSA). There is evidence that quercetin metabolites are able to strongly displace warfarin from HSA suggesting that quercetin at high doses can interfere with warfarin therapy. 

This interaction has been shown more with quercetin supplements or muscadine grapes; they have higher quantities of quercetin. 

Follow this link for more information on what food to avoid if taking warfarin. 


In this article we answered Can you eat kale when taking warfarin, what is kale, is it healthy to eat kale, what is warfarin, what happens if you eat kale when taking warfarin, and what food you should avoid if taking warfarin. 


Hi, I am Charlotte, I love cooking and in my previous life, I was a chef. I bring some of my experience to the recipes on this hub and answer your food questions.