If your doctor has prescribed you blood thinners, such as Coumadin or Warfarin, then you’ve probably been told to stay away from vitamin K or to monitor your intake of it. Vitamin K is actually a group of compounds made up of vitamin K1 and vitamin K2. Most commonly found in vegetables and leafy greens, most of us consume vitamin K on a daily basis. 

What’s interesting is that vitamin K helps your blood clot naturally, so your cuts and scrapes heal. So for those who take blood thinners, vitamin K can counteract the medication, meaning they essentially working against each other.

Vitamin K and INR

Patients go on blood thinners for many reasons but mainly when they are at risk for blood clots or have had a blood clot in the past. Those with conditions such as Factor V may be on blood thinners for life, while others may take drugs like Coumadin temporarily, depending on the doctor’s recommendations. 

To tell how well the medication is working, patients will get regular blood tests that measure how long it takes their blood to clot. After reviewing the International Normalized Ratio (INR) values, a doctor may adjust the dosage of medication because INR must not be too high or too low.

Unfortunately, vitamin K can change how well the blood thinner medication works, which then changes INR values, making it difficult for physicians to evaluate whether or not the medication works. Vitamin K lowers INR values, which means it takes less time for blood to clot. A low INR value indicates that the drug is not working well enough. It’s important for doctors to have an accurate INR in order to medicate their patients appropriately.

Staying consistent with vitamin K intake

Patients taking Coumadin or Warfarin are advised to keep vitamin K intake consistent on a daily basis. Some physicians may suggest staying away from vitamin K completely, or at least until INR levels are consistent. 

To keep intake consistent, it’s crucial to know what foods have high levels of vitamin K. The most obvious foods are leafy greens such as kale, spinach, and swiss chard; however, you might be surprised to find some foods you regularly consume also have high levels. Here is a list of common foods and their amounts of vitamin K to help.

Patients are often reminded to look at food labels to be sure and to watch multivitamins and supplements as well. If you plan to have a kale salad three days a week, for example, be sure to talk to your doctor about introducing this amount of vitamin K and remain consistent in this amount. 

Those taking Coumadin also have to remember to take the medication at the same time every day, which means consistency is key in managing this health concern. Talk to your doctor about vitamin K levels, keeping in mind that he or she will recommend a consistent amount on a daily or weekly level.

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