Warfarin and Vitamin K – Why You Need Both

If you’ve been diagnosed with a blood clot, chances are you are taking a blood thinner, which is very commonly Coumadin or warfarin. If you’re like me and have been diagnosed with a clotting disorder or have a high chance of reoccurring blood clots, you might even be taking warfarin for the rest of your life. The prospect of having to monitor a potentially dangerous condition, let alone take medication forever, is overwhelming and worrisome for many, including myself. Warfarin can be difficult to manage, is not entirely safe for your liver over an extended period, and has some pretty notable interactions with other vital nutrients, mainly vitamin K. In fact, you may have even been told by a medical professional to stop eating foods high in vitamin K. While warfarin and vitamin K do interact, the potential harm of completing eliminating vitamin K from your diet may be proven to be more dangerous than creating a consistent level of it in your blood.

Why Vitamin K Matters

Vitamin K is a naturally occurring vitamin most commonly found in green, leafy vegetables such as spinach, broccoli, and lettuce (see an extensive list of foods here). Your body uses vitamin K from foods you eat and also bacteria in your intestines to produce some of the factors that help your blood clot.

Why Warfarin Matters

Warfarin interferes with how your body uses vitamin K by preventing the production of vitamin K clotting factors in your liver. This can cause clotting to occur at a much slower rate and creates the potential for unwanted bleeding problems or additional clotting in your veins.

How Does Vitamin K Affect My INR?

Changes in the amount of vitamin K you consume through your diet can alter the liver’s ability to process warfarin and change the amount of blood-thinning properties in your body. Your INR refers to a standardized way to measure how quickly your blood is clotting. The lower your INR, the more quickly the blood clots or the “thicker” the blood. If your INR is too low, you could be at risk for further clotting. The higher your INR, the longer it takes the blood to clot or the “thinner” the blood, putting you at risk for bleeding problems. With an increase in vitamin K, your INR level may drop, creating the potential for unwanted clotting.  A decrease in vitamin K intake may increase your INR, creating the potential for unwanted bleeding.

What We’ve Been Told

Most of us have been told to avoid vitamin K like the plague.

Beyond the Blood Thinner – Why You Need Vitamin K

We are taking warfarin, it’s depleting our body’s natural vitamin k stores – which are important for a variety of things, most notably preventing the hardening of arteries in the heart, potentially creating serious health implications – and we are being told not to replace it.

A New Way of Thinking

It is not about eliminating vitamin K from your diet. It is about consistency. For example, if you eat two servings of foods per day that are high in vitamin K, you should continue doing that. If you don’t eat foods rich in vitamin K at all, do not suddenly decide to eat large amounts of them. Clot Care also confirms, “It is a common misconception that people on warfarin should avoid Vitamin K. Reducing your vitamin K intake can cause your INR to increase and may make it more difficult to control. Rather than avoiding vitamin K, you should maintain a consistent intake of vitamin K by maintaining a consistent diet. In other words, from week to week, you should eat the same types of foods.”

Nowhere does it say, never ingest vitamin K, you can never eat salad again, or kiss that calming cup of green tea goodbye. It is about consistency and slowly reintroducing vitamin K foods into your diet if you desire to and have previously eliminated them.

Yes, You Can and Should Consume Vitamin K

You do not have to avoid foods or other products that are high in vitamin K; these foods have many other vitamins and minerals that are part of a healthy diet, particularly when it comes to your heart. The most important thing to remember about vitamin K intake is being consistent as much as possible and communicating any changes that may occur.

But that’s Not What My Doctor Said

Unfortunately, I think it is easier for doctors to tell you to avoid vitamin K (and all of the wonderful, nutritious, satisfying foods that go with it) because it is just plain easier. This way, doctors can build a baseline for your warfarin dosing without having to worry about vitamin K obtained from foods and nutrients affecting your INR. Chances are you were not consuming green leafy vegetables on a consistent enough basis to include a vitamin K allowance in your treatment planning. Sure, we all enjoy a salad now and again or eat broccoli once in a while with dinner, but how many of us (truly, honestly, let’s stop kidding ourselves for one moment) could say without a doubt that we were eating three cups of spinach four days a week, a half a cup of broccoli or green beans two nights a week and scallions in our omelet every other Sunday? It’s difficult to say unless you are very conscious of it and most of us grossly underestimate the number of greens we actually consume, even though we should be consuming them frequently.

Almost Everyone I know who takes Warfarin Avoids Vitamin K

Not anymore. I remember the first time I posted that I was taking a vitamin K supplement in an online forum. It was in regards to a forum member’s frustration over her inability to maintain a therapeutic INR level. I posted- “I am taking warfarin and also vitamin K, both prescribed and monitored by my doctor. I started taking vitamin K after being on Arixtra injections [blood thinners that are injected into the stomach daily] for over ten months, which was concerning to my doctor because Arixtra is non-reversible [you cannot be given an anecdote to stop bleeding if you are seriously injured, for example in an accident] and there is not a lot of research about adverse effects to the body [beyond a typical-length pregnancy in which women are often put on injections to reduce the risk of clotting]. In light of some successful research, my doctor decided to actually put me on a low dosage of vitamin K to create a balance of warfarin and vitamin K in my blood. Within a month or so, my INR stabilized for the first time since leaving the hospital and I have not been on injections since. I also posted this link to some of the research that I could find myself.

I remember the first comment my reply received, “Sara, you need to get a new doctor pronto because yours will certainly kill you if you are taking vitamin K.” More of the like ensued and no one backed me up, leading me to believe I was alone in my treatment and my treatment’s success.

I was horrified. Since the beginning, I had trusted my doctor – he had after all found the Antiphospholipid Antibodies when the Emergency Room Doctors were all too hasty to send me away with three-month course of blood-thinning therapy blaming my DVT and severe PE on birth control and birth control alone. My case was so severe that a specialist was called in, my now hematologist, who I credit with saving my life and providing me with the ongoing care I so desperately need and will need from here on out. He had not yet steered me wrong. He explained what happened, my treatment, and what to expect in recovery when no one else had, not a single person.

There was no chance I doubted him on vitamin K. I kept up with my treatment. I ate greens about as consistently as I had – a few times a week and slowly increasing as I worked to get my diet and weight loss back on track. Through it all, I keep him informed of any major changes and continue to get my INR monitored at the least, bi-weekly.

What Should I Do?

Talk to your doctor. We need to be an advocate for our own health and we cannot let blood thinners determine how we choose to live our best lives.

Discuss incorporating vitamin K-rich foods back into your diet with your doctor; taking a supplement or alternative treatments (i.e. Xarelto) that do not affect vitamin K. Also discuss the implications of the absence of vitamin K in your body.

It is also important to keep in mind that other things impact the body’s vitamin K production and warfarin’s ability to metabolize including, but not limited to vitamins, nutritional supplements, antibiotics, bacteria/viruses, illness, and stress.


Share your Story. What are your thoughts on vitamin K and warfarin? Do you take or eat foods rich in vitamin K? Why or why not? What did your doctor tell you about vitamin K? Did you read the heart-healthy article? What are your thoughts on needing vitamin K?

There is hope for healing and you are not alone,


How to track and manage your INR with OATBook

OATBook Review Title Photo

I left the hospital after a total of ten days, five of which were spent in the cardiac intensive care unit (ICU) after my DVT and PE. I wasn’t even sure what happened to me – although I had a vague idea that I was lucky to be alive from what I kept hearing – and was even less sure of what would happen next. I left on Arixtra injections, a cousin to Lovenox anticoagulant medication, only with less clinical research available and non-reversible if I were to be in an accident and have uncontrolled bleeding. I don’t think I even knew what that mean beyond, “Don’t get in an accident.” I heard the injection, which I was prepared to administer myself, but not prepared for the increasing difficulty of it, would keep my INR stable. ‘INR’ was completely new to me and something I hoped would go away in a week or two.  What is INR and how can you manage your INR with OATBook?

INR stands for international normalized ratio. The INR provides some information about a person’s blood’s tendency to clot (which is often described as how “thin” or “thick” their blood is). There are several scientific factors as to why and how this number is evaluated to be as reliable as possible. A normal INR is approximately 1.0. People taking the blood thinner warfarin (oral) typically have a target INR of 2.0 to 3.0, although it all depends on your body and what you and your doctor have discussed. People with an INR higher than the normal range who aren’t taking warfarin may have a medical condition that needs further evaluation. A low INR is rarely significant.

Injections (such as Arixtra or Lovenox), while extremely expensive (I was looking at $2,300 before my deductible for 20 injections), are often easier to regulate in terms of INR as long as you are able to give yourself an injection at the same time each day, which I was. When taking an oral anticoagulant such as warfarin (Coumadin), a patient usually has to have weekly blood draws (at least in the beginning) to monitor INR.

I was on those injections for ten months as a result of my INR’s inability to stabilize, making it increasingly difficult for my body to transition to an oral anticoagulant such as warfarin. When my doctor did try to switch me to the warfarin, I became immensely confused with all of the different dosages and blood draws – not to mention remembering to take my pill – in part because I was also battling slight loss of cognitive function and memory as a result of my illness and trauma. While I was told this was a normal side effect, it was difficult because when the nurse called to give me my dosages for the week, they literally went in one ear and out the other before I even had a chance to write them down. So, I would guess (and get it wrong) and my INR suffered greatly in terms of highs and lows, forcing me to go back on the injection each time.

I came off the injection again at the beginning of April of this year and have remained mostly stable since then. Warfarin is more practical for many because it is cheaper, has been a part of long-term safety and side effects research and is much easier to administer. People have been on it for life and have done okay, if not well – people have not been on Arixtra for life to date. It is reversible if I were to be severely hurt or injured, which takes a big worry off my mind.

What’s different this time? Well, it is true that my cognitive abilities and memory have grown much stronger, and I am better now than I was ten, six or even three months ago, but the transition to oral anticoagulation therapy would not have been possible this time without the OATBook. The OATBook is a mobile phone app that helps you track, monitor and store your complete INR history in one place; keep your dosage times consistent and never miss a dose; and stores your appointments and reminders.

I literally could not manage my INR without it and it has become a crucial part of my Oral Anticoagulation Therapy, as the name OATBook suggests.

The OATBook took a little time for me to get used to, but once I did, I quickly found it was essential to managing my warfarin dosages, INR levels and blood draws. Plus, it lets me know via an alarm when to take my medication daily (11:32 p.m.) and will continue to go off until I check that I have done it. It also reminds me when I need to get a prescription refill-

SS medication is almost out on home screen

It is invaluable to me that I can also set a reminder to get my INR checked (I have a standing order at the hospital clinic so I choose when I want to go, as long as it is the same time each week) and the app charts my levels-

SS graph of INR range

I can also send or save it if I need to take it to a doctor (who is not my hematologist)-

SS email your graph

You can see, for May 1, how I got my INR checked, had an appointment and checked off that I took my pill that night-

SS options screen with notes, meds, inr

You can customize OATBook to remember the important things like what your therapeutic INR level is and there is also a place on each day to record notes-

SS settings where you can set your INR range

If you are are like me and your dosage changes daily, you can set each day to be different in OATBook or you can have it auto-fill the same dosage each day for the month-

SS entering your dosage


You can download OATBook for iPhone and you can also find a user guide and answers to frequently asked questions. I found the customer service was very helpful and prompt when I didn’t realize you swipe right to left on the days to make the options appear (it took a minute to get used to, but I have no problems now).

Share your story. How do you keep track of your INR? Was it or is it a struggle for you? Have you heard of or used OATBook?

In healing there is hope and you are not alone,