Probiotics and Warfarin

By: Alere Staff

Reading package labels has become a must for any consumer, much less one who is on anticoagulation therapy. With so many labels on foods, sometimes it can get confusing to even the most health-conscious shopper. What makes something “vegan”? How can someone tell the difference between “natural” and “organic”? To add to the mix of labels, companies are starting to tout the benefits of probiotics and live cultures. What are probiotics and what do packages labeled with "Contains Live Active Cultures" have to do with a patient on warfarin? 

What is a Probiotic?

The dictionary describes a probiotic as usually a dairy food or a dietary supplement containing live bacteria that replace or add to the beneficial bacteria normally present in the gastrointestinal tract.¹ Foods such as yogurt and cheese as well as sauerkraut and pickles may contain probiotics or have probiotics added to them.

The idea of consuming living organisms or becoming a host may sound like an episode of reality television. However, in most cases these are positive bacteria. The "normal flora" of the gastrointestinal tract includes the good bacteria Lactobacillus, Bifidobacterium, and about 400 other strains of bacteria, fungi, and parasites.2,3 Before you start squirming uncomfortably, know that these organisms are vital and help us to metabolize different foods, absorb nutrients, prevent “bad” bacteria from landing on intestinal walls and overall help maintain intestinal health.2,3

Where to Find Probiotics

Now that you know what they are, where can someone find a food with probiotics? Pre-packaged foods usually don't contain them, as processing food with heat and/or preservatives tends to kill off the probiotics. The foods labeled with "contains live active cultures" are more likely to contain viable probiotics at the time of purchase.4 As previously mentioned, dairy products like yogurt and milk are good sources of probiotics as well as fermented cabbage foods like sauerkraut and kimchi. Other sources include pickles, tempeh, Kombucha tea, olives, miso soup and sometimes even dark chocolate.3

There are several species of probiotics as well, including a common species called Lactobacillus which is used in over-the-counter supplements. Physicians may at times prescribe probiotics along with antibiotic therapy to prevent antibiotic-associated diarrhea. Probiotics are thought to have a variety of beneficial effects in the human host and are thought to block colonization of pathogenic bacteria on the intestinal wall by competing for space and nutrients. Other ways in which probiotics may assist with your health are by producing metabolic products that have antibacterial effects and by helping build a body’s immune system.4

While very few side effects have been reported with probiotics, patients on warfarin should be cautious and speak with their health care provider to determine if using these in their everyday diet is advisable.4 The way probiotics affect a person’s immune system depends on their health status. It’s also important to remember that one probiotic product should not be considered the same as another, as genetic strains of the bacteria may differ.4 If your physician does recommend using this type of supplement, use as directed.


1. Dictionary:

2. Saavedra, JM. Probiotics Plus Antibiotics: Regulating Our Bacterial Environment. J Pediatr, 1999; 135:535-7.

3. Gregory PJ. Probiotics for Antibiotic-Associated Diarrhea. Pharmacist's Letter / Prescriber's Letter. 2000;16:160103.

4. Natural Database: