Blood Thinners and Greens: A Mix to Avoid?

September 12, 2016 , ,

You might have heard that if you take an anticoagulant (blood thinner), like Coumadin (warfarin), you should stop eating, or at least eat fewer, green vegetables, because they contain too much Vitamin K. But is this really the case?

Before getting right into the topic, let’s review some basics. Firstly, it’s important to note that Coumadin (generic name: warfarin) is an anticoagulant, which means it stops the formation of blood clots and makes blood thinner (less viscous). As for Vitamin K, it helps the process of blood clotting. In other words, warfarin has the opposite effect to Vitamin K.

What is INR (International Normalized Ratio)? And how does it vary?

The INR is a test used by doctors and pharmacists to check the effectiveness of blood thinning medication (Coumadin/warfarin) and to adapt the dosage. Ideally, you should maintain as stable an INR as possible, meaning you should maintain an optimal blood coagulation rate.

Several factors can influence and unbalance this rate, the seven main ones are:

  • Travelling
  • Moving home
  • Depression
  • Divorce
  • Bereavement
  • Malnutrition
  • Dementia

Other factors include genetics, diet, adherence to treatment and other medications you may be taking. Natural supplements are included in the list of medicines that can affect INR.

Natural Supplements and Anticoagulation Therapy


For your information, here are a few examples of natural products that could influence your INR more than eating green vegetables:

  • Those which increase INR values:
    • Boldo and fenugreek
    • Cranberry juice (in large quantities)
    • Danshen
    • Devil’s Claw
    • Dong Quai
    • Garlic capsules
    • Ginger
    • Ginko biloba
    • Mayweed
    • Papain
    • Vitamin E (in doses larger than 400 units/day)
  • Those which reduce INR values:
    • Coenzyme Q10
    • Ginseng
    • Green tea (in large quantities)
    • St. John’s Wort

Always speak to your pharmacist before you start or stop taking a supplement. If you take supplements, make sure you tell your doctor and your pharmacist.

Now that we’re reviewed some basic facts, let’s get to the nitty gritty: diet and its effect on medication! Several vegetables, particularly green ones, contain Vitamin K, in varying quantities. As mentioned earlier, warfarin (Coumadin) is a Vitamin K antagonist. Its presence or absence from the diet can play a role in the medication’s effectiveness.

Why You Shouldn’t Avoid Green Vegetables

food basket, paniel d'aliments

Two main reasons can explain why reducing your intake of green vegetables is not necessary, even if you’re going through anticoagulation therapy.

Firstly, despite what you might have heard, the presence of Vitamin K in the diet helps better balance your INR. Indeed, regularly eating vegetables, particularly green ones, helps you to be less sensitive to daily variations in Vitamin K. This is explained by the fact the liver stocks some Vitamin K, because it is a fat soluble vitamin.

For example, if you eat green vegetables every day, your liver stores Vitamin K. If, one day, you have a lower intake of Vitamin K, this will have practically no repercussions. Vitamin K stored in the liver will be used. This way, you can maintain you INR as stable as possible. However, if you never eat green vegetables, you don’t have Vitamin K stores, so if you eat a good amount of green vegetables one day, you’ll experience a “peak” of Vitamin K, which will then destabilize your INR.

Secondly, Vitamin K’s bioavailability depends on several factors like cultivation, storage and cooking of foods. What’s more, we only know the Vitamin K content of around half the food in the North American diet. It’s therefore practically impossible to establish and respect a recommended daily intake of Vitamin K.

For these reasons, we recommend an intake of 1 to 2 portions of green vegetables each day, even for those taking Coumadin. This quantity enables you to have a better control of your medication and to meet the nutritional needs established by Health Canada. What’s more, green vegetables are great for health!

Note: if you are a fan of Asian cuisine and regularly eat natto (a traditional Japanese food made from fermented soya beans), it would be a good idea to avoid it, because it contains a large quantity of Vitamin K (much higher than what is commonly found in vegetables), which can influence your INR.

Main food sources of Vitamin K


High Content Cabbage, Brussels sprouts, spinach, kale, turnips
Average Content Asparagus, avocado, broccoli, carrots, celery, cauliflower, red cabbage, cucumber, watercress, green beans, oils (canola, olive, soya), lettuce (Boston, Iceberg, romaine), fresh parsley, leek, green peas, tomato

So, in answer to the original question, no, it isn’t necessary to avoid green vegetables because the Vitamin K they contain enables a better control of both coagulation and medication. Good to know, those who have the most difficulty managing their INR are often those who do not eat (or do not eat enough) Vitamin K and green vegetables.

Our heart-healthy menus are approved by the nutritionists at EPIC, Montreal Heart Institute’s Center for Preventative Medicine, even for their anticoagulation therapy patients. Why not give them a try to help plan your meals?




Jef L'Ecuyer
Member of the Quebec College of Dietitians (ODNQ) and Dietitians of Canada,Jef graduated from McGill University in December 2014. Recently graduated and passionate about culinary arts, Jef poses a simple, effective and practical look at daily meal planning. With this in mind, she works in conjunction with the mission of SOSCuisine...

48 comments to “Blood Thinners and Greens: A Mix to Avoid?”

February 11, 2019 Virginia Davis said:

Your article did not mention collard greens. Are they high in vitamin K as well? My mother loves collard greens and taking Warfarin at the moment. Her doctor has said no to green veggies. I hope that this article can apply to her.

Cinzia Cuneo
February 11, 2019 Cinzia Cuneo said:

Hi Virginia,
Yes, the same applies to collard greens. Your mother needs to keep her consumption always at about the same level.

February 19, 2019 marlin said:

ALWAYS first check with your healthcare pro before starting supplements OR changing your dietary preferences. You can shock your metabolism and totally mess it up. What works for some don’t work for all. Many supplement also interact with med’s or other supplements. Don’t take chances, as first.

February 19, 2019 Spencer Ryce said:

Blood thinners are medicines that prevent blood clots from forming. They also keep existing blood clots from getting larger. Clots in your arteries, veins, and heart can cause heart attacks, strokes, and blockages.

There are two main types of blood thinners. Anticoagulants such as heparin or warfarin (also called Coumadin) slow down your body’s process of making clots. Antiplatelet drugs, such as aspirin, prevent blood cells called platelets from clumping together to form a clot.

March 15, 2019 Luciano Tortorici said:

Very clarifying and helpful article. Thank you.

April 12, 2019 Daniel said:

Hello, I have been taking warfarin and clopidogrel for several years now, 10mg warfarin daily and 75mg of clopidogrel. I also take nicorandil,bisiprolol,atorvastatin,ramipril and bumetanide. My INR has dropped to 1.2 and I’m not able to travel to the hospital for two or three days due to mobility issues, I have no money to pay for public transport either. My diet has changed for the better recently and I’m consuming many more potions of green leafy vegetables. Could this have had such a drastic impact on my INR? should I be worried?

Jef L'Ecuyer
April 12, 2019 Jef L’Ecuyer said:

> Hello Daniel!

Improving your diet and consuming more leafy greens can definitely have an effect on your INR. You should check-in with your medical team to make sure your medication is adjusted accordingly.

April 25, 2019 Spencer Ryce said:

Anticoagulants such as heparin or warfarin (also called Coumadin) slow down your body’s process of making clots. Antiplatelet drugs, such as aspirin, prevent blood cells called platelets from clumping together to form a clot. When you take a blood thinner, follow directions carefully.

May 5, 2019 Neal said:


Jef L'Ecuyer
May 6, 2019 Jef L’Ecuyer said:

> Hi Neal!

Unless contraindicated by your medical team, you can eat a variety of veggies. There is no vegetable that should be left out, just make sure to have a serving of green veg everyday.

May 11, 2019 Pam Busby said:

I love fresh turnip greens when in season. I’m taking Eliquois since I had a stroke last January. Should I stop eating turnip greens?

Cinzia Cuneo
May 21, 2019 Cinzia Cuneo said:

Hi Pam,
If you like them, you should eat them. In fact you should have a serving of green veg everyday.

May 23, 2019 Steve said:

My mom had a stroke and is now on Plavix, low dose aspirin, and Lipitor daily. I’m doing the cooking and regularly use fresh garlic, lime, lemon, parsley, ginger, cabbage, kale, basil, and rosemary and dried spices like oregano, black pepper, red pepper, lemon grass, Herbs du Provence, and Korean spices like gochujang. Should I cut any of these out of her diet to avoid harmful interactions with her medications?

Cinzia Cuneo
May 24, 2019 Cinzia Cuneo said:

Hi Steve,
As mentioned in the article, it is important that your mom keeps her leafy greens consumption constant, for example always one serving per day.

May 28, 2019 kim glover said:

I am on warafin for prone to bloodclots in my leg. I have my own blood testing machine and todays results were 3.6,,so, if I eat more salad with spinach in it, will that help bring my level down where it should be?

July 5, 2019 Ana said:

Hi! I have just started taking Xarelto. Should I avoid greens?

Cinzia Cuneo
July 10, 2019 Cinzia Cuneo said:

Hi Ana,
As explained in the article, you should not avoid eating greens. You should only pay attention to keep the consumption always at about the same level.

July 22, 2019 Linda Brown said:

hello I am taking medications like Lisinopril, amlopodine, atorvastatin clopidogrel, plavix aspirin. I eat broccoli three days a week is this a bad idea

August 21, 2019 Marcia Green said:

Hi, I am confused, if your INR is at 3 does that mean your blood is thick and say 1 means it is thin? Lower number means thin??

December 4, 2019 Sue Thornley said:

I am taking Apixaban
tablets after a blood clot last Christmas in my lungs. Is it ok for me to eat green veg despite the clot? I would be grateful to receive your views. I do miss eating them. Also, should I be avoiding any type of food? Thank you.

Cinzia Cuneo
December 11, 2019 Cinzia Cuneo said:

Hi Sue,
As explained in the article it is important to keep a regular pattern of eating greens.

January 31, 2020 Mohamad J Farshid said:

Thanks for advice on consuming green veggies while using blood thinners ,it’s very helpful,since I always was worrying that this two don’t match (vitamin K and blood thinners) thanks again and keep the good work .God bless you

February 16, 2020 PATRICIA said:

I had dtp in my left leg in 2016 9 days in the hospital was told i would off of warfarin in 6 months then i my check up i was told because of my a-fibal i would have take them the rest of my life. and to cut out eat all leafy green vegetables .or how often a day or week should i eat them . have not had any to eat since 2016 my INR
come good i get it check once a month i eat thing string all the time . Can peas sometime i love collard- salad- turnips salad- cabbage but scare too eat any of them. need answers now HELP ME PLEASE

Cinzia Cuneo
February 17, 2020 Cinzia Cuneo said:

Hi Patricia,
As you can read in the article, if you eat greens, make sure to maintain their intake always at the same level.

February 20, 2020 Patricia Elizabeth Schmidt said:

My husband has been on Coumadin for almost a year without reaching a good reading. First it’s too low and then it’s way too high. My husband had salad last night and then his level was high. What does it take to get his levels to an acceptable level?

May 11, 2020 Richard Krempulec said:

Very good article. I take Taro-Warfarin as I have a mechanical valve. I was overweight and a diet doctor put me on a diet about two years ago where I eat 3 salads a day and lost 20 pounds. I continue to eat 3 salads a day of which at least 2 have lettuce of various kinds.

My INR over the last year has been very irregular and I maybe eating too many green vegetables. You suggest that generally one should eat a “good portion” and an intake of “1 or 2 portions of green vegetables” . I am not sure what is a good portion or a portion. Can you be more specific as to the amount you are referring to as a portion.

Cinzia Cuneo
May 17, 2020 Cinzia Cuneo said:

Hi Richard,
According to the American Heart Association, a serving of a raw, green leafy vegetable like romaine lettuce, arugula or spinach is 1 cup. The serving size for all cooked veggies (fresh, frozen and canned) is ½ cup.

May 23, 2020 Rose said:

Is taking 0.009mcg vitamin K harmful when on Plavix

Cinzia Cuneo
May 27, 2020 Cinzia Cuneo said:

Hi Rose,
Please ask your pharmacist.

June 1, 2020 Spencer Ryce said:

Blood thinners prevent blood clots, which can stop blood flow to the heart. Learn about how they work, who should take them, side effects, and natural remedies.

Blood thinners are medications taken orally or intravenously (through a vein) to prevent a blood clot. Blood clots can stop the flow of blood to the heart, lungs, or brain. They can cause a heart attack or stroke.

The presence of blood thinners in your system can increase your risk of internal bleeding after an injury. Go to the hospital right away if you experience any of these side effects after falling or bumping your head — even if you don’t have external bleeding.

Your doctor may tell you to limit your participation in contact sports to reduce the risk of bleeding. However, this doesn’t mean you can’t exercise or live a normal life. Swimming, walking, and jogging are excellent forms of exercise and are safe for most people taking anticoagulants. Discuss with your doctor which types of exercise may be best for you.

June 14, 2020 Yan Shifrin said:

I’m taking warfarin for many years. Can I use dietary supplement such as “Metabolic Green Plus”?

Cinzia Cuneo
June 15, 2020 Cinzia Cuneo said:

Hi Yan,
You should ask your pharmacist about possible interactions.

July 9, 2020 Thresa said:

I have just recently been put on BRILINTA. I am having a stent put in on July 24. I have a blockage but I have not had a heart attack. I know that it can cause bleeding so my question is I have very low platelet counts could this be a problem. I’m also suffering from extreme constipation.

Cinzia Cuneo
July 23, 2020 Cinzia Cuneo said:

Hi Thresa,
As mentioned several times, what it important is to keep the green veggy consumption to a constant level.

July 15, 2020 Upali Fernando said:

I am taking clopidogrel and aspirin ( 1 75 mg tab. every morning and evening ) for the past 3 years after I had heart by pass surgery. Is it ok to take red cabbage and green cabbage ( each one quarter of a small flower) regularly ?

October 19, 2020 Annie Thomas said:

I had a blood clot in my heart last May 2020. I was put on Eliquis 5mgs twice a day. Is it safe to eat fresh spinach turnip and greens with talking eliquis? Need to know – my diet is suffering from no greens and salads

October 30, 2020 Ruby said:

Hello, I am searching for a happy medium in eating dark green veggies while taking warfarin….Please help!!!!

Cinzia Cuneo
November 5, 2020 Cinzia Cuneo said:

Hello Ruby,
You should subscribe to our Heart Healthy meal plans.

November 16, 2020 Arlene W. Dingwall said:

> Thank you. Appreciated the info.

May 20, 2021 Kerwin said:

Warafin is a cursed drug that is like a roller coaster ride. It is frustrating to monitor it and get blood tests which is normal.

June 29, 2021 Parinitha Bhargav said:

Where human is eager to earn great health, nature has its own contribution to help him. Very helpful information with regards to nutrition and energy. Thank you for sharing the post.

August 18, 2021 MalindaAntonette said:

Had a blood clot in my lung about April 2021. I take different dosses of warfarin each day. One day may be 5mg, next day will be 7.5. Usually my INH is about 2.50 -2.80. Few times got into the 3.0, but rarely. I love GREENS of all kinds. I was told like you tell people, in moderation daily. So, looked up on the web how much a certain green veggie, cooked or raw to use per serving. I am craving green beans, ham and potato cooked together. Will make nuff for 2 meals. This is how I plan my meals. Oh, but I LOVE GREENS. Can’t live without them. Ty for your web site. MalindaAntonette

Cinzia Cuneo
August 22, 2021 Cinzia Cuneo said:

Hi MalindaAntonette,
You may want to try our meal plans for Cardiovascular Conditions

October 27, 2021 Patricia said:

I couldn’t agree with you more!!!!!!!

April 13, 2022 Maryetta Christie said:

Not on Blood thinners but am having tooth extracted plus bone graft under that gum, I started drinking smoothie
W/ 6 cups kale w/ added water , banana and pineapple !
Is that ok or too much kale before extraction?

Cinzia Cuneo
April 13, 2022 Cinzia Cuneo said:

Hi Maryetta,
There should be no problems, but please double check with your dentist.

April 24, 2022 Betty said:

When one is on an organic diet and has to have a hip operation how long a wait as a patient in hospital to have blood regulated for the HIP OPERATION? Please reply to my question asap.

Cinzia Cuneo
April 25, 2022 Cinzia Cuneo said:

Hi Betty,
We cannot answer this question. You must ask your medical team.

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