The Definitive Coumadin Diet Guide

One of the first things a person hears when prescribed Coumadin (Warfarin) is that Vitamin K interacts with it and to be mindful about their diet. But what does that mean exactly?

Coumadin diet decisions

When I was prescribed Coumadin, one of the most challenging things was having consistent INRs. Vitamin K isn't listed on food labels and there are so many different things that can impact your Coumadin therapy that it's hard to know where to start.

Here are ACTIONABLE ways you can maintain your Coumadin Diet and reduce INR fluctuations.

This article will cover everything you consume, including food, alcohol, smoking (inlcuding marijuana), over the counter medications and supplements, and more.

Let's get started.

Contents

Don't try to avoid Vitamin K

One of the biggest misconceptions about a proper Coumadin Diet is that Vitamin K should be avoided.

Avoiding Vitamin K is usually the wrong approach.

First, studies have shown that those that omit, or try to consume low amounts of Vitamin K have more INR fluctuations than those who don't.1

Second, Vitamin K is nearly impossible to avoid, especially since it is not listed on food labels. Simply avoiding anything “green” won't work because there are other foods that impact Coumadin (we'll get to that later).

The key is consistency, but how do you do that?

Low Dose Vitamin K Technique

Green pills 2

Many people taking Coumadin use the Low Dose Vitamin K Technique, which involves taking low dose Vitamin K supplements (always consult with your doctor before changing your diet or taking supplements!).

Here's how it works.

For example, on Monday you take your Vitamin K supplement of 100 mcg and eat 50mcg of Vitamin K. That is a total of 150mcg of Vitamin K on Monday.

On Tuesday, you take your Vitamin K supplement of 100mcg and eat 100mcg of Vitamin K. That is a total of 200mcg of Vitamin K on Tuesday.

From Monday to Tuesday, your Vitamin K total went up by 33%.

Now, let's say you didn't take a Vitamin K supplement at all, but still ate 50mcg on Monday, and 100 mcg on Tuesday, then your Vitamin K total would have gone up by 100%!

By taking a daily low dose Vitamin K supplement your total Vitamin K changes less day-to-day. Hence, your Warfarin dosages will change less often and your INR will be more consistent.

Understanding Vitamins, a little

Before we dig deep into specific foods (and we will), it's important to know how Vitamins work in the body.

There are two types of Vitamins:

  1. Fat-soluble vitamins include Vitamins A, D, E and Vitamin K
  2. Water-soluble vitamins include Vitamins B and C

What is the difference between fat-soluble and water-soluble?

Solubility explains how the vitamin behaves in the body. Both fat-soluble and water-soluble vitamins are absorbed and used by the body as needed. The difference is how the body absorbs the vitamin and how it handles the excess that the body doesn't immediately use/need.

In the case of water soluble, the vitamin is absorbed into the body using water, and the extra is excreted through urine. Therefore, you need to make sure to keep restoring water soluble vitamins because your body doesn't store any reserves.

For fat-soluble vitamins (Vitamin K), the vitamin is absorbed into the body using fat (lipid) and the excess is stored in the body for later use.

Since the body keeps the fat-soluble vitamins, it is possible for the body to keep too much, resulting in hypervitaminosis (toxicity). However, this is uncommon and usually the result of high supplement intake and not from dietary sources.

There has never been a case of Vitamin K toxicity.3

So how is the Low Dose Vitamin K Technique safe?

Vitamin K is actually pretty complicated and I'm not going to cover every detail, but here is a basic overview.

There are three types of Vitamin K:

  • Phylloquinone (K1): This form is found in plants and is consumed in the diet. It is absorbed better when it is consumed with fat. This is the type used in most Vitamin K supplements.
  • Menaquinone (K2): This form can be found in non-plant foods like meat and fermented foods like cheese. Bacteria in the intestine also produce it. There are actually 13 sub-types of Menaquinone. MK-4 is considered the most important.
  • Menadione (K3): Is synthetic and sometimes used in animal food, not human food.

Although Vitamin K is a fat-soluble vitamin and stored in fat, very little is actually saved in the body and constant Vitamin K intake is still necessary.4

Since the body doesn't save much Vitamin K, the body recycles what it does have through a process called the Vitamin K-epoxide cycle.

Vitamin K Cycle

Vitamin K and Coumadin

Warfarin works by preventing the body from recycling Vitamin K. As a result, there is less Vitamin K in the body.

Warfarin essentially creates a Vitamin K deficiency. What does a Vitamin K deficiency mean for your body? Let's learn some history.

Vitamin K, a little history

Chickens 5

Vitamin K was awarded the letter K due to its role in coagulation processes (koagulation in German). It was discovered in 1929 after an experiment on a cholesterol-depleted diet for chickens. The diet also (unknowingly) lacked Vitamin K. As a result the chickens started to hemorrhage (bleed).

The same happens to humans. Without Vitamin K people will bleed excessively if their body encounters trauma.

This is a risk for newborn babies. Vitamin K isn't easily transferrable from the mother to the child in utero. Most babies are given an injection of Vitamin K (K1) after birth to help them clot blood and prevent excessive life-threatening bleeding.

Coumadin treats and prevents blood clots by limiting the Vitamin K in the body so that the blood clots less. The reason people have an INR is to measure how well Coumadin is working in the body. If Coumadin is depleting too much Vitamin K, then your INR will be high and you'll be at risk for bleeding. If your INR is too low then that means Coumadin isn't depleting enough Vitamin K to treat / prevent clots.

Eating Fats with Vitamin K

So why is knowing how Vitamin K works important? It is important because Vitamin K relies on fat to absorb into the body.

A "low fat" diet, is not advised because Vitamin K is only absorbed into the body when eaten with fat.6 The same applies to other fat-soluble vitamins too.

The daily-recommended fat intake should be 20 to 35 percent of your daily calories. For example, if you consume 2,000 calories a day, then you should be eating 44 to 77 grams of total fat a day.

Daily Fat Intake Calculator

Vitamin E

Studies have shown that high-dose Vitamin E supplements may interact with Vitamin K.7 This shouldn't impact most diets, only those who may be taking Vitamin E supplements (at 800 IU or more).

Be sure to speak with your doctor if you are taking, or plan to take Vitamin E supplements.

Multivitamins

K free daily multivitamin

Multivitamins are a great way of obtaining all your daily required nutrients. Unfortunately, most multivitamins contain Vitamin K which may or may not be part of your recommended coumadin diet.

K Free Daily is a multivitamin designed for people on anticoagulants. It does not contain Vitamin K or other nutrients research shows may interfere with INR.

Understanding food chemistry, a little

Now that we understand how Vitamin K works, we can finally move on to foods.

The Vitamin K content of over 4,000 foods can be found in our Vitamin K Food Database absolutely free. The information is taken from the USDA.

Although we have information on a lot of foods, the majority of pre-processed foods do not have Vitamin K information anywhere.

I even tried calling the number on the back of food labels that says “Questions? Call 1-800-555-5555)” but was never given an answer (we will talk more about food labels later).

Understanding the basic mechanics of food and how they are manufactured and sold will help fill in the gaps for the missing foods in our database.

This will enable you to make informed decisions with limited information.

Cooked vs Raw

When you browse through our food database you will likely discover that the vitamin content in foods are different when the food is cooked vs raw.

Some vitamins will become lost when exposed to heat (Vitamin C, for example).

Vitamin K does not degrade with heat. No matter how long you cook something, its Vitamin K content will remain.

However, when browsing the food database you may notice that raw and cooked ingredients have wildly different Vitamin K content.

For example, raw kale has around 113 mcg of Vitamin K in one cup, but one cup of cooked kale has 1062 mcg of Vitamin K.

The difference in Vitamin K is not caused by heat during cooking, but rather the reduction in volume. As you probably know, when you cook kale or any other lettuce it'll whittle down significantly. So one cup of cooked kale is about 10 loosely packed cups of raw, uncooked kale.

Dried herbs vs fresh

Some herbs, like Basil, Thyme, and Oregano, contain different amounts of nutrients in their dried and fresh forms.

For example, one tablespoon of dried basil has 77 mcg of Vitamin K. One tablespoon of fresh basil contains 10 mcg of Vitamin K.

For cooking, roughly one part dried herb is equal to three parts fresh herb.

Exposure of Vitamin K to Sunlight

Sunset 8

Vitamin K is sensitive to sunlight (Photo-oxidation).

Sunlight is able to destroy Vitamin K, but it depends on the form it is in. Of course the Vitamin K in vegetables isn't destroyed by sunlight, otherwise they wouldn't have any to begin with because they grow in the sun!

In fact, one study showed that spinach received MORE Vitamin K (and other vitamins) when exposed to supermarket lights.9

However, oils (which are typically made from vegetables and contain Vitamin K) oxidize and degrade when exposed to light. In fact, exposure of oils to sunlight or fluorescent light for at least 48 hours destroys approximately 85% of the vitamin K.10

Olive oil contains around 8 mcg of Vitamin K in one tablespoon. So 85% reduction of that is around 1mcg of Vitamin K.

Although it might seem like a good idea to place your oils in direct sunlight, and many websites suggest Coumadin users do this, I wouldn't recommend doing something like that and here's why.

Kevin oleary

Olive oil connoisseurs (yes they exist, just ask Kevin O'Leary) would cringe at the thought of exposing Olive oil to light. It degrades the product significantly, which is why it destroys Vitamin K (along with other nutrients) when exposed to light.

Olive oil should be kept in a cool, dark place, in an airtight container. It should not be refrigerated and should be used within 2 years of purchase.

So even though sunlight may destroy “85%” of Vitamin K in sunlight, there is no at-home way of measuring the success of doing that, and you'll only end up with a poor quality oil to cook with.

The key is to just limit, or be mindful, about how much you consume.

Since Olive oil only contains around 8 mcg of Vitamin K in one tablespoon, it is fine to use in limited amounts.

Oils

Olive oil 11

On the subject of oils, they tend to have Vitamin K. Why? Because they are often made from plants. Olive Oil is made from...olives. Vegetable Oil is made from vegetables, so on and so on.

Although small amounts of oil is ok, it is important to note because oils are used in a lot of other products.

Food Labels

The “ingredients” section on food labels is always listed in order from most to least. This is required by law.

Although you won't exactly know how much of each ingredient is there, you will be able to know what the dominant ingredients are.

For example, if you see oils towards the front of the list, you will know that the product contains a lot of it, and hence has a decent amount of vitamin k.

Additionally, since oils are fats that are liquid at room temperature. Products that are "low fat" tend to contain fewer oils than their full calorie-counterpart, and have less vitamin k.

Mayonnaise

Mayonnaise, both commercial and homemade, contains oil. Regular mayonnaise has around 22mcg of Vitamin K in one tablespoon. Light mayonnaise has 8mcg per tablespoon.

Alternatives to Mayonnaise:

Hummus 12

Hummus
Hummus contains less than 1mcg per one tablespoon.

Tahini 13

Tahini
Tahini contains 0 mcg of Vitamin K.

Yellow Mustard 14

Yellow Mustard
Yellow mustard contains less than 1mcg of Vitamin K per one tablespoon.

Margarine

Margarine is a butter alternative made from vegetable oils and animal fat. Margarine spread contains around 14mcg of Vitamin K in one tablespoon.

Alternatives to Margarine:

Sour Cream 15

Sour Cream
Sour cream has around 2mcg of Vitamin K per one cup.

Ricotta Cheese 16

Ricotta Cheese
Ricotta cheese has around 3mcg of Vitamin K per one cup.

Hummus 12

Hummus
Hummus contains less than 1mcg per one tablespoon.

Salad Dressings

Salad dressings often contain oils, especially commercial ones. Ranch dressing, for example, contains around 19mcg of Vitamin K per tablespoon.

Alternatives to Salad Dressings:

Lemons17

Lemons
Fresh squeezed lemon juice with a dash of salt and pepper make a delicious and healthy dressing. Lemons have 0 Vitamin K.

Fried Foods

Any food cooked in oil is going to absorb a lot of it. For example, one serving of Applebee's Crunchy Onion Rings contains 144mcg of Vitamin K.

Alternatives to Fried Foods:

Try to consume foods that are baked or grilled instead of fried.

Tuna Fish

Tuna fish alone barely has Vitamin K. However, Tuna fish packed in oil contains 64mcg of Vitamin K in one cup.

Alternatives to Tuna Fish:

Try tuna fish packed in water instead of oil.

Other Foods to Know

The following foods are known to interact with Coumadin and should be consumed with caution.

Grapefruit

Grapefruit 18

Grapefruit will increase the level or effect of Coumadin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Significant interaction possible, monitor closely. 42

Cranberries

Cranberries 19

Cranberries increases effects of Coumadin by unknown mechanism. Cranberry may inhibit cytochrome P450 2C9. Theoretical interaction, based on case reports. Minor or non-significant interaction. 42

Garlic

Garlic 20

Garlic and Coumadin both increase anticoagulation. Potential for dangerous interaction; Use with caution and monitor closely. 42

Ginger

Ginger 21

Ginger and Coumadin both increase anticoagulation. Potential for dangerous interaction; Use with caution and monitor closely. 42

Turmeric

Turmeric 22

Turmeric and Coumadin both increase anticoagulation. Potential for dangerous interaction; Use with caution and monitor closely. 42

Beverages

Water

Dehydration causes your blood vessels to become narrow which will result in viscous blood.

Drinking lots of water and staying hydrated is one of the best ways of preventing blood clots.

I will say this again.

Drinking lots of water and staying hydrated is one of the best ways of preventing blood clots.

The first thing you should do when you wake up is drink a tall glass of water, because that is when you are most dehydrated.

Coffee

Coffee does not directly interfere with Coumadin. However, coffee is a diuretic which can cause dehydration, increasing the risks of blood clots. Again, drink plenty of water to prevent dehydration.

Alcohol

Alcohol (ethanol) may impact your INR, however, it is not usually necessary for you to avoid consuming it (consult your doctor). Two major reasons why is because both Coumadin and alcohol are absorbed using the liver, which may have a temporary reduction in function from alcohol. Also, consuming alcohol can greatly impair judgment and may increase chances of injuries that could cause excessive bleeding.2

Alcohol may increase the effects of Coumadin with binge drinking. Alcohol also dehydrates the body which can cause the blood to be more viscous, increasing the risks of blood clots. It's best to not drink alcohol, but if if you do, you should limit yourself to only 1 or 2 drinks a day.

Smoking

Of course it is common knowledge that smoking is bad, but I am not here to pass judgement on anyone. It is important to know how smoking will impact your Coumadin therapy if you are a smoker.

Tobacco

Smoking will decrease the level or effect of Warfarin by affecting hepatic enzyme CYP1A2 metabolism.42

Nicotine itself does not interact with Coumadin, only the smoke caused from cigarette smoke impacts Warfarin. Nicorette, for example, will not impact Warfarin.42

You need to tell your doctor if you are trying to quit smoking because your reduction in use will very likely impact your INRs.

Marijuana

Marijuana (pot, weed, mary jane, dope, cannabis) will increase the level or effect of Coumadin by affecting hepatic/intestinal enzyme CYP3A4 metabolism.42

Marijuana should be avoided when used with Warfarin.

Greens

Every Coumadin user knows that green foods contain Vitamin K. Here is a Coumadin diet list of green foods that contain high Vitamin K.

Top Green Foods

Food Name Measure Vitamin K Per Measure (mcg)
Kale
Kale23
Raw 1 cup loosely packed 112
Cooked, Boiled, Drained, Without Salt 1 cup 1062
Frozen, Cooked, Boiled, Drained, Without Salt 1 cup 1146
Frozen, Cooked, Boiled, Drained, With Salt 1 cup 1146
Collards
Collards24
Raw 1 cup 157
Frozen, Chopped, Cooked, Boiled, Drained, Without Salt 1 cup 1059
Frozen, Chopped, Cooked, Boiled, Drained, With Salt 1 cup 1059
Cooked, Boiled, Drained, Without Salt 1 cup 773
Cooked, Boiled, Drained, With Salt 1 cup 773
Spinach
Spinach25
Raw 1 cup 145
Frozen, Chopped or Leaf, Unprepared 1 cup 580
Frozen, Chopped or Leaf, Cooked, Boiled, Drained, Without Salt 1 cup 1027
Frozen, Chopped or Leaf, Cooked, Boiled, Drained, With Salt 1 cup 1027
Cooked, Boiled, Drained, Without Salt 1 cup 888
Cooked, Boiled, Drained, With Salt 1 cup 888
Canned, Regular Pack, Drained Solids 1 cup 988
New Zealand Spinach26
New Zealand Spinach, Cooked, Boiled, Drained, With Salt 1 cup 525
New Zealand Spinach, Raw 1 cup 189
New Zealand Spinach, Cooked, Boiled, Drained, Without Salt 1 cup 526
Turnip Greens
Turnip Greens27
Raw 1 cup 138
Frozen, Cooked, Boiled, Drained, Without Salt 1 cup 851
Frozen, Cooked, Boiled, Drained, With Salt 1 cup 851
Cooked, Boiled, Drained, Without Salt 1 cup 529
Cooked, Boiled, Drained, With Salt 1 cup 529
Canned, No Salt Added 1 cup 413
Frozen, Cooked, Boiled, Drained, Without Salt 1 cup 677
Frozen, Cooked, Boiled, Drained, With Salt 1 cup 677
Beet Greens
Beet Greens28
Raw 1 cup 152
Cooked, Boiled, Drained, Without Salt 1 cup 697
Cooked, Boiled, Drained, With Salt 1 cup 697
Dandelion Greens
Dandelion Greens29
Raw 1 cup 428
Cooked, Boiled, Drained, Without Salt 1 cup 579
Cooked, Boiled, Drained, With Salt 1 cup 378
Mustard Greens
Mustard Greens30
Raw 1 cup 144
Frozen, Cooked, Boiled, Drained, Without Salt 1 cup 503
Frozen, Cooked, Boiled, Drained, With Salt 1 cup 503
Cooked, Boiled, Drained, Without Salt 1 cup 830
Cooked, Boiled, Drained, With Salt 1 cup 830
Brussels Sprouts
Brussel Sprouts31
Raw 1 cup 156
Frozen, Cooked, Boiled, Drained, Without Salt 1 cup 300
Frozen, Cooked, Boiled, Drained, With Salt 1 cup 300
Cooked, Boiled, Drained, Without Salt 1 cup 219
Cooked, Boiled, Drained, With Salt 1 cup 219
Broccoli
Broccoli32
Raw 1 cup 92
Spears, Frozen, Unprepared One 10oz package 292
Spears, Frozen, Cooked, Boiled, Drained, Without Salt 1 cup 162
Spears, Frozen, Cooked, Boiled, Drained, With Salt 1 cup 183
Frozen, Chopped, Unprepared 1 cup 267
Frozen, Chopped, Cooked, Boiled, Drained, Without Salt 1 cup 162
Frozen, Chopped, Cooked, Boiled, Drained, With Salt 1 cup 162
Cooked, Boiled, Drained, Without Salt 1 cup 220
Cooked, Boiled, Drained, With Salt 1 cup 220
Cabbage
Cabbage33
Cooked, Boiled, Drained, Without Salt 1 cup 163
Common, Cooked, Boiled, Drained, With Salt 1 cup 163
Japanese Style Cabbage, Fresh, Pickled 1 cup 189
Mustard Cabbage, Salted 1 cup 148
Chinese Cabbage34
Chinese Cabbage, Pak-choi, Cooked, Boiled, Drained, Without Salt 1 cup 58
Chinese Cabbage, Pak-choi, Cooked, Boiled, Drained, With Salt 1 cup 58
Lettuce
Butterhead Lettuce35
Butterhead Lettuce (Includes boston and bibb types), Raw 1 cup 56
Romaine Lettuce36
Romaine Lettuce (Cos lettuce), Raw 1 cup 48
Green Leaf Lettuce37
Green Leaf Lettuce, Raw 1 cup 46
Iceberg Lettuce38
Iceberg Lettuce (Includes crisphead types), Raw 1 cup 17
Asparagus
Asparagus39
Raw 1 cup 56
Frozen, Cooked, Boiled, Drained, Without Salt 1 cup 144
Frozen, Cooked, Boiled, Drained, With Salt 1 cup 144
Cooked, Boiled, Drained, With Salt 1 cup 91
Cooked, Boiled, Drained 1 cup 91
Canned, No Salt Added, Solids and Liquids 1 cup 95
Canned, Drained Solids 1 cup 100
Okra
Okra40
Raw 1 cup 31
Frozen, Unprepared 1 cup 142
Frozen, Cooked, Boiled, Drained, Without Salt 1 cup 88
Frozen, Cooked, Boiled, Drained, With Salt 1 cup 88
Cooked, Boiled, Drained, Without Salt 1 cup 64
Cooked, Boiled, Drained, With Salt 1 cup 64

Salads

If you want to enjoy a salad or have lettuce as part of your coumadin diet, it is recommended that you eat iceburg lettuce.

One cup of iceburg lettuce contains only 17 mcg of Vitamin K.

Over the Counter Medications

Here are some common over-the-counter medications and how they interact with Coumadin.

Always consult with your doctor before taking any over-the-counter medications.

Additionally, some brands may contain a variety of ingredients. Be sure to look on the back of the package to confirm which ingredients are used in products. The interactions listed here are based on the "Drug Name" not the "Brand Name."

Pain Medications

Compatibility Drug Name Brand Names Type of Interaction
Acetaminophen Tylenol Acetaminophen increases effects of Coumadin by unknown mechanism. This is a minor / non-significant interaction.42
Aspirin Alka Seltzer
Bayer
Bufferin
Excedrin
Coumadin and Aspirin both increase anticoagulation. Potential for dangerous interaction; Use with caution and monitor closely.42
Ibuprofen Advil
Motrin
Coumadin and Ibuprofen both increase anticoagulation. Potential for dangerous interaction; Use with caution and monitor closely.42
Naproxen Sodium Aleve
Midol
Coumadin and Naproxen both increase anticoagulation. Potential for dangerous interaction; Use with caution and monitor closely.42

Allergies

Compatibility Drug Name Brand Names Type of Interaction
Dipenhydramine Benadryl No known interactions.42
Brompheniramine Dimetapp No known interactions.42
Loratadine Alavert
Claritin
No known interactions.42
Brompheniramine Dimetapp No known interactions.42
Fexofenadine Zantac No known interactions.42
Cetirizine Zyrtec No known interactions.42

Cold and Flu

Compatibility Drug Name Brand Names Type of Interaction
Guaifenesin Mucinex
Robitussin
No known interactions.42
Dextromethorphan NyQuil Cough No known interactions.42
Pseudoephedrine HCl Sudafed No known interactions.42

Upset stomach, gas, constipation, laxative, and diarrhea

Compatibility Drug Name Brand Names Type of Interaction
Bismuth Subsalicylate Pepto-Bismol Potential for serious or life-threatening interaction; may require intervention to minimize or prevent serious side effects. Never use Pepto-Bismol while taking Coumadin.42
Loperamide Imodium No known interactions.42
Simethicone Gas-X No known interactions.42
Bisacodyl Dulcolax No known interactions.42
Polyethylene Glycol Miralax No known interactions.42

Heartburn

Compatibility Drug Name Brand Names Type of Interaction
Omeprazole Prilosec Omeprazole will decrease the level or effect of Coumadin by affecting hepatic enzyme CYP1A2 metabolism. Significant interaction possible, monitor closely.

Omeprazole will also increase the level or effect of Coumadin by affecting hepatic enzyme CYP2C9/10 metabolism. Significant interaction possible, monitor closely.

Omeprazole will also increase the level or effect of Coumadin by affecting hepatic enzyme CYP2C19 metabolism. Minor or non-significant interaction.42
Calcium Carbonate Tums
Rolaids
No known interactions.42
Fexofenadine Zantac No known interactions.42
Famotidine Pepcid No known interactions.42
Citations (view all)
see all posts

Trending Discussion Posts

Start managing your Warfarin Register for Free