probiotics

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What are probiotics? Probiotics are generally defined as live microbial organisms that are used medicinally to help improve the intestinal bacterial flora.[1] [2] Probiotics can be consumed as functional foods or as a supplement if they are in a capsule or pill form. The Food and Nutrition Board of the Institute of Medicine defines a functional food as, “Any food or food ingredient that may provide a health benefit beyond the traditional nutrients that it contains.”2 An example of a functional food would be fortified milk. Lactobacillus and Bifidobacterium genera are two of the most common types of bacteria found in probiotic supplements.

Potential benefits of probiotics: Probiotics have been used to treat several different ailments including: diarrhea, inflammatory bowel disease, irritable bowel, lactose intolerance, and yeast infections.1 [3] [4] Probiotics work by attaching themselves to the walls of the intestine.[5] The probiotic bacteria then increase the number of good bacteria and fight harmful bacteria such as salmonella, shigalla, and E. coli.[6] It is thought that probiotic bacteria may fight off harmful bacteria by acidifying the colon which prevents the growth of the harmful bacteria.6 Probiotics also restore the body’s production of vitamin K and B vitamins in the intestine.

Potential drug interaction between probiotics and warfarin: Warfarin works by interfering with the liver’s synthesis of vitamin-K dependent clotting factors.[7] One of the main counseling points associated with warfarin therapy is about products/foods that might contain vitamin K and how they can counteract the effects of warfarin. If probiotic bacteria increase the amount of vitamin K, theoretically the patient would need more warfarin to inhibit the synthesis of the vitamin K dependent clotting factors. There have not been any studies done that have looked specifically at the effects of probiotics on warfarin; however, if the theory above is correct then a patient’s INR would decrease if they started to take probiotics while on warfarin therapy. Due to the increased production of vitamin K a patient’s warfarin dose would need to be increased if the patient was going start or continue taking probiotics. Another important point to keep in mind here is that vitamin K is a fat soluble vitamin. Due to the fact that vitamin K is a fat soluble vitamin, the vitamin K is going to stay around longer.

Patient case: We have a patient at the anticoagulation clinic who is taking probiotics. One thing that we have noticed about this patient is that not only is she taking probiotics but she is also taking several other herbal/natural products, these include: CoQ10, multivitamin and mineral, B complex, vitamin E, vitamin C, garlic, zinc, calcium, flaxseed, and alfalfa. As we can see from this patient’s profile she is taking various herbals that could potentially interact with her warfarin therapy. At this patient’s first visit her INR was 1.0. An INR of 1.0 is not therapeutic; however, with so many herbals where do you start to try and get a therapeutic INR? It is difficult to get these patient’s to discontinue their herbal/natural products because the patient’s feel that the products play a vital role in their health. We recommended that this patient discontinue her probiotics to see if that would help her INR reach a therapeutic range. The patient did discontinue the probiotics; however, at the following visit (2 weeks later) her INR still was not therapeutic. As explained above the patient’s low INR was not a surprising finding. The extra vitamin K is likely stored in the fat tissue and released slowly back into the blood; therefore, it could take several weeks for us to see any profound effects from the discontinuation of the probiotics. At this visit the patient also mentioned that she felt like she really needed her probiotic because she had been having some digestive problems so she was going to restart the probiotic therapy. Therefore, her warfarin dose was increased about 20% and she will have her INR tested every 7-10 days

Conclusion: Probiotics are usually taken to help improve the body’s natural intestinal bacteria. Probiotics can potentially interfere with warfarin therapy because probiotics produce vitamin K that is used by the body to produce clotting factors. A person who is taking probiotics may need to have their warfarin dose adjusted in order to reach a therapeutic INR. This is just one example of a patient who was taking probiotics while on warfarin. From this example you can see that the patient was taking several herbal/products that could interact with her warfarin. In addition, it is difficult to get these patients to discontinue their herbal products.

One last thing to think about is that dietary supplements such as probiotics have little regulation in the United States. The FDA requires that the manufacturers list the ingredients but the manufacturers do not have to prove that the product is safe and efficacious like other drugs. Lastly, even thought the manufacturer must list the ingredients on the package the FDA does not perform any type of chemical analysis to verify what is listed on the package; therefore, you really don’t even know what you are buying.

[1] Floch MH, Montrose DC. Use of probiotics in humans: an analysis of the literature. Gastroenterology

Clinics of North America 2005;34:547-570.

[2] Halsted CH. Dietary supplements and functional foods: 2 sides of a coin? American Journal of Clinical

Nutrition 2003;77(supplement):1001S-1007S.

[3] US Probiotics resource page. Probiotic Basics Web site. Available at: http://www.usprobiotics.org/bascis.

Accessed on 11/15/05

[4] Mayo Clinic.com. Lactobacillus acidophilus. Available at:

http://www.mayoclinic.com/health/lactobacullus/NS_patient-acidophilus. Accessed on 11/15/05.

[5] Irish Health.com homepage. Probiotics and your health. Available at:

http://www.irishhealth.com/clin/ffl/probiotics.html. Accessed on 11/15/05.

[6] Kornax.com. Lactobacillus acidophilus and other probiotics supplements. Available at:

http://www.kornax.com/Acidophilus.htm. Accessed on 11/15/05.

[7] Lexi-Comp. Lexi-Comp’s Drug Information Handbook. 12^th ed. Hudson: Lexi-Comp;2004.

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