Exactly What Happens To Your Body When You Start Taking A Probiotic? Experts Weigh In

mbg Editorial Assistant By Abby Moore
mbg Editorial Assistant

Abby Moore is an Editorial Assistant at mindbodygreen. She earned a B.A. in Journalism from The University of Texas at Austin and has previously written for Tribeza magazine.

Expert review by Marvin Singh, M.D.
Integrative Gastroenterologist
Dr. Marvin Singh is an Integrative Gastroenterologist in San Diego, California. He is trained and board certified in Internal Medicine and Gastroenterology/Hepatology.
what happens to your body when you start taking a probiotic?

Sure, you may have heard that probiotics can have a positive influence on gut health—but, have you ever questioned why? What are the gut-friendly bugs so many people talk about, and what exactly happens to the body when they're added to a supplement routine?

To get a clear picture of what probiotics do and how to tell if they're working, mbg spoke with functional medicine doctors and gut health experts. Here's what they have to say about what happens when you start taking probiotics.

What happens when you take a probiotic?



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Probiotics are a live bacteria that help support gut health.* When you take a probiotic supplement, you contribute more good bugs to your gut.* "The probiotics are like good cops," Robert Rountree, M.D., renowned integrative physician, previously told mbg. "We're putting in the good cops, and the good cops can keep watch over the bad guys."

By introducing good bacteria to the gut microbiome, probiotic supplements and foods are meant to manage dysbiosis and promote healthy digestion.* A healthy microbiome can enhance immune functioning; manage bloat, diarrhea, and constipation; and even support mood because of the gut-brain connection.*  

Since they are literally alive, functional medicine doctor Amy Shah, M.D., says probiotics will metabolize differently for different people. Depending on a person's existing gut health, they may take longer to start working or lead to adverse effects initially. 

That said, “The longer you take a probiotic, the more diverse your microbiome will become, and the stronger your immune system and GI tract get,” integrative physician Bindiya Gandhi, M.D., says.* 


How do you know if it's working?

For some people, probiotics can start to work within 24 to 48 hours, Shah says, while others may not experience results for weeks. Significant changes in the gut microbiome could even take months to settle in.

The physical changes may vary from person to person, but if a probiotic is working properly, the effects should be noticeable. 

According to Gandhi, an effective probiotic will lead to less bloating, gas, abdominal discomfort, and constipation.* "For some it will translate to less fatigue, less brain fog, more energy, and being able to eat foods they could not tolerate before," she adds.* 

That said, it's important to remember that a probiotic is not a cure-all and that proper diet, stress reduction, exercise, and other lifestyle measures are key to helping those good gut microbes grow and flourish.

Are there any potential side effects?

Before seeing improvements, some people may experience negative gastrointestinal side effects. "Many people can get gas or bloating in the first week or two since it's new bacteria for your ecosystem," Shah explains.  

Eventually, these effects should dissipate. If they don't, stop taking probiotics and consult a gastroenterologist or primary care physician for other treatment options. 

These lasting side effects may be indicative of existing health conditions, like small intestine bacterial overgrowth (SIBO) or irritable bowel syndrome (IBS), which would require more personalized attention.  


What happens if you stop taking a probiotic?

External effects, including environment, diet, prescriptions, and more, can change the microbiome daily. "But when you stop taking probiotics for at least three days, your microbiome changes drastically," Gandhi says.

Pausing or stopping supplementation altogether will likely cause the microbiome to reset to its original state of dysbiosis, especially if old habits remain.

Bottom line.

When you start taking a probiotic supplement, you introduce good bacteria into your gut.* This may lead to a number of benefits such as healthy digestion and less bloating, gas, or abdominal discomfort. If you experience any long-term side effects, chat with your doctor to make sure you're taking the best possible probiotic for you.


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