Probiotics: pros and cons

Are probiotics good for your stomach? Do probiotics help the gut microbiome? Can probiotics cure irritable bowel syndrome (IBS)? Probiotics have been a hot topic for several years now and continue to gain popularity.  They have been hailed as a potential solution for numerous gut health problems. What exactly are probiotics and does the published research match the hype?



If you’ve read our post on the microbiome, you know bacteria play a big role in how the gut works. There are good and bad bacteria that make up the trillions of microbes in our gut, and probiotics are simply defined as live microorganisms that, when taken in adequate amounts, confer a health benefit on the host. By ingesting more of the “good” bacteria in the form of probiotics, we can theoretically make our gut healthier and in turn improve digestive health.  

Probiotics are often marketed as fermented foods (our post on the topic) that naturally contain live microbes (i.e. yogurt, kimchi, kombucha), however experts do not define these foods as probiotics, and for the purposes of our discussion we are going to discuss probiotics taken as a pill or supplement. These formulations tend to have a higher concentration of bacterial species that have been shown to positively affect the gut but as we will see the data is mixed.



Now for the real question. It may come as no surprise that probiotics ability to improve your GI symptoms are both variable and dependent on the underlying problem at hand.  As with our overall understanding of the gut microbiome, our comprehension of probiotics is still in its early stage, and most doctors would advise that probiotics are harmless to try but that few patients experience significant benefit from them. What does the data show?

IBS: For irritable bowel syndrome, there is data suggesting benefit but overall the consensus is somewhat mixed, similar to other dietary interventions such as the FODMAP diet. That’s not to say they don’t work - some patients certainly derive benefit from probiotics - but overall the effect is modest. In studies that have shown benefit, it has been in formulations with combinations of bacterial strains rather than any one particular strain of bacteria.

Traveler’s diarrhea: We plan on unpacking (pun-intended) what defines “traveler’s diarrhea” into a future post, but the short story here is no, probiotics are not helpful for preventing or treating traveler’s diarrhea.

Infectious diarrhea: There is a solid body of evidence that probiotics help decrease the duration and severity of infectious diarrhea.  There is also encouraging data that probiotics can help reduce the risk of diarrheal infection caused by antibiotics. Keep in mind that these types of diarrhea have a wide range of severity, ranging from mild to life-threatening. For any serious infection, probiotics are only part of a multifaceted approach, and should be used in coordination with advice from medical professionals tailored to your individual needs.



There seems to be little harm in adding probiotics to your regimen. Unfortunately, the FDA only tests products classified as drugs and many probiotics are manufactured as supplements, so no commercially sold probiotics are FDA approved.  For this reason, what you see on the bottle is rarely what you are putting in your body: one study showed that only 1 out of 16 probiotic formulations actually contained the microbes it claimed. Another showed mild side effects in up to 16% of patients who used them, so they are not completely without harm.



Enthusiasm for probiotics is stronger than quality scientific research proving their benefit. More research is needed to know for sure if probiotics can make a significant difference in our health. If you’re going to take a probiotic, FDA-approved is more reliable than commercial products. While current knowledge suggests probiotics may not solve your gut problems, they may be a helpful, low-risk addition to your regimen depending on your underlying issue.


-The Gut Docs*

*This was a guest post co-written by a doctor passionate about probiotics research


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