Photo of a small white mug of tea on a wooden coaster with overlay of blog article title--"green tea and blood thinners: yes, no, or maybe?".
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If you enjoy green tea or have been thinking about adding it to your lifestyle, you may be wondering if there are any interactions you need to be aware of, especially if you’ve been prescribed blood thinners.

One classic example of a blood thinner that many of my heart patients have been prescribed is warfarin. A prescription of warfarin usually comes with the reminder to be mindful of your intake of foods high in Vitamin K. Portion size matters here.

A beverage that people have asked me about in regards to warfarin intake is green tea. It does contain Vitamin K, but amounts do tend to differ in the leaves themselves versus the brewed tea.

So if recommendations for green tea and warfarin are seemingly mixed, then what about other types of blood thinners? Should a blanket statement be made that green tea and blood thinners don’t mix?

Not necessarily. Let’s explore the evidence.

Quick disclaimer—although I am a registered dietitian nutritionist, your reading of this or any articles on this website does not constitute medical nutrition therapy advice nor create a practitioner-client relationship. The information I provide here on this website is for educational and informational purposes only. Please see my full disclaimer for more information.

Types of Blood Thinners

Let’s first begin with blood thinners themselves. While my goal is not to get too deep into the science, it is important to know that blood thinners as a whole have different ways that they work.

At this time there are 2 generally recognized categories of blood thinners: anticoagulants and anti-platelets.1 These category descriptions tell us where in the blood clotting process the type of blood thinner works.

For example, antiplatelet medications work a little earlier in the clotting process to prevent platelets from sticking together.2 Anticoagulants work in a later part of the process, slowing down some of the rest of the steps involved in clotting.1

Because the process of clotting has many little steps,3 it makes sense that different compounds from foods and beverages could potentially interfere with medications’ work at various points in the process. 

Detailing all of these possible food-drug interactions is far beyond the scope of this article; so let’s get back to the reason we’re here: green tea.

Can I Drink Green Tea If I’m Taking Blood Thinners?

The short answer here would be that it depends. Ultimately, a discussion with your doctor, pharmacist, and dietitian would be the best plan, since everyone is different. Your medical history, lifestyle, and other medications may play a big part in determining if green tea is right for you to drink.

But that doesn’t mean that we can’t outline a few things here that you may want to bring up to your healthcare team when you speak with them.

Can I drink green tea if I'm taking blood thinners infographic.

Amount and Forms of Green Tea

It deserves mention that when we’re discussing green tea, we may be talking about more than a simple cup of brewed tea. In recent years, many types of green tea related supplements seem to have popped up in the dietary supplement industry.4

You may be seeing green tea extract by itself or added to various foods and beverages for sale today. The supposed health benefits of these products are often advertised quite convincingly, even though we may not really have much data to back up all of these claims.4

That being said, it’s important to realize that the green tea extract could potentially be far more concentrated and potent than a simple cup of steeped green tea. Although individual situations are different, in my professional opinion, I would be very wary of using concentrated green tea supplements while you’re on blood thinners, as there may be potential interactions.5

In contrast, a smaller cup (such as 8 fluid ounces) of steeped green tea will likely not be nearly as concentrated as an extract would be. Based on the information available thus far, it may be okay to add the occasional cup of green tea to your day if you’re on blood thinners. But double check with your healthcare providers to be sure it is okay for you to do this.

Consistency in Drinking Green Tea

Now back to the topic of warfarin and green tea. Since warfarin is the main blood thinner where Vitamin K intake is important, let’s discuss green tea in this context. Although a small cup of steeped green tea may be pretty low in Vitamin K,6 the effect may start to increase the more you drink it.

If you take warfarin and your healthcare team has told you it’s okay to drink green tea, keep in mind the consistency principle. To be safe, try not to drastically increase or decrease the amount of green tea you drink in a short period of time.

Even foods with a low amount of Vitamin K can become higher sources of Vitamin K if consumed in much larger amounts; so always notify your healthcare provider if you intend to make any significant changes to your dietary habits.

Conclusion

Although the final verdict regarding green tea and blood thinners is not exactly a definite yes or no, just remember that that’s how nutrition today is—it’s not a one-size-fits-all. We are all different, with different lifestyles and nutrition goals.

If you feel overwhelmed with all of the nutrition information out there, I would encourage you to find a dietitian to help you personalize your nutrition plan to meet your goals and lifestyle needs. Find out more here: https://www.eatright.org/find-a-nutrition-expert

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Sources

  1. Blood Thinners. Medlineplus.gov. Updated January 31, 2022. Accessed April 28, 2024. https://medlineplus.gov/bloodthinners.html.
  2. Antiplatelet Drugs. My.clevelandclinic.org. Updated May 5, 2022. Accessed April 28, 2024. https://my.clevelandclinic.org/health/drugs/22955-antiplatelet-drugs.
  3. Palta S, Saroa R, Palta A. Overview of the coagulation system. Indian J Anaesth. 2014;58(5):515-523. doi: 10.4103/0019-5049.144643.
  4. Cerbin-Koczorowska M, Waszyk-Nowaczyk M, Bakun P, et al. Current view on green tea catechizes formulations, their interactions with selected drugs, and prospective applications for various health conditions. Appl. Sci. 2021;11(11):4905.  https://doi.org/10.3390/app11114905.
  5. Green Tea Oral Dosage Forms. My.clevelandclinic.org. Accessed April 28, 2024. https://my.clevelandclinic.org/health/drugs/20553-green-tea-oral-dosage-forms.
  6. Beverages, Tea, Green, Brewed, Regular. Fdc.nal.usda.gov. Accessed April 28, 2024. https://fdc.nal.usda.gov/fdc-app.html#/food-details/171917/nutrients.

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