The human microbiome plays a critical role in our health. It’s made up of trillions of microbes – including bacteria, fungi, viruses and other microorganisms – that coexist in harmony and interact with cells to keep our bodies functioning properly. While the microbiome is located in different parts of your body, the gut is home to the largest colony of microbes that affects your digestive system, immune system and inflammation.

So how do you maintain a healthy gut microbiome? The answer: prebiotics and probiotics.

While probiotics are the “good” bacteria – or live cultures – found in your gut, prebiotics are nutritional compounds found in food that promote the growth of probiotics. In tandem, prebiotics and probiotics are good for your gastrointestinal health.

”Keeping a healthy environment in your gut is critical to not only optimizing your health but also staving off chronic disease,” says Amy Kimberlain, a registered dietitian and certified diabetes educator based in Miami and spokesperson for the Academy of Nutrition and Dietetics. “What you choose to eat determines the amount of ‘good’ versus ‘bad’ bacteria that are taking up residence in your gut.”

For most people, eating a healthy diet that’s high in fiber, with plenty of fruits, vegetables and whole grains, will provide enough prebiotics to help your body naturally produce its own probiotics without needing to take nutritional supplements.

Prebiotics Basics

To obtain the benefits of probiotics, you first need to consume enough foods with prebiotics.

“Prebiotics are, in essence, food for the probiotics,” Kimberlain says. “Probiotics need the prebiotics in order to help promote their growth and activity in the colon.”

Prebiotics are natural, non-digestible food components that promote the growth of helpful bacteria in the gut. They’re found in high-fiber, whole-grain foods, as well as foods you might not expect.

Good food sources of prebiotics

You can get prebiotics from a wide array of foods, including:

Benefits of Probiotics

Probiotics are beneficial bacteria that live in our digestive tract and play an important role in digestion. Research suggests that probiotics promote the health of the digestive tract lining, help support immunity and are important in managing inflammation.

In a 2019 study published in the journal Annals of Nutrition and Metabolism, researchers found that providing oral probiotics supported a healthy immune system response. Furthermore, research published in 2003 in the Scandinavian Journal of Gastroenterology showed that probiotics may be helpful in reducing the risk of diarrhea associated with taking antibiotics.

Some research also suggests that certain probiotics may help improve mood and shield against depressive symptoms. In 2017, the Annals of General Psychiatry published a review of 10 studies assessing whether probiotics can help with depressive symptoms. Researchers found that the majority of these studies reported positive results in treating depressive symptoms, providing compelling evidence that probiotics alleviate depressive symptoms. In addition, a meta-analysis published in the journal Nutrients in August 2016 found that probiotics were associated with a significant reduction in depression.

Do You Need a Probiotic Supplement?

Kimberlain and other experts agree that most people can get the prebiotics and probiotics they need from eating a balanced, healthy diet without taking probiotic supplements.

In June, 2020, the American Gastroenterological Association released guidelines that do not recommend the use of probiotics for most digestive conditions.

Dietary supplements of any kind, including probiotics, aren’t tested by the U.S. Food and Drug Administration the way traditional medicines are, which means there’s no way to be certain about the effectiveness of what you’re purchasing. While prebiotic and probiotic supplements have the potential to improve gut health in people with certain conditions, these products aren’t regulated by the FDA and may not have been tested in humans, says Dr. Pratima Dibba, a board-certified gastroenterologist with Medical Offices of Manhattan in New York City. In some cases, marketers of probiotic supplements claim that their products can help people with certain digestive conditions without solid research to back up their claims.

For example, there’s limited and inconclusive research to support that probiotic supplements may be helpful in treating certain conditions, including irritable bowel syndrome, small intestinal bacterial overgrowth, diverticular disease and nonalcoholic fatty liver disease, Dibba says.  

Some probiotics supplements are marketed as a treatment for certain stomach-related ailments such as irritable bowel syndrome, celiac disease and constipation, but the evidence as to their effectiveness for these conditions isn’t conclusive, adds Dr. Laura Purdy, a board-certified family medicine physician based in Nashville, Tennessee.

Fermented foods

Fermented foods may provide probiotics. Check for a “live and active culture” label to ensure that your fermented food product contains living or active probiotics – as not all do:

While most people can get enough probiotics from a healthy diet, probiotic supplements may help certain individuals. Anyone with gastrointestinal issues should talk to their doctor before taking probiotic supplements.

How to Increase Your Fiber Intake

To get the probiotics your body needs, it’s important to consume a balanced diet with plenty of fiber, which helps keep your good bacteria at healthy, proper levels and promotes the growth of probiotics.

But eating a high-fiber diet has other health benefits: It lowers cholesterol, regulates blood sugar and helps with weight control. When eating a high-fiber diet, drink plenty of water to avoid constipation.

Here’s how to increase the amount of fiber in your diet:

When to Talk to Your Doctor

If you’re having stomach problems, it’s important to see your primary health care provider instead of trying to self-treat with supplements.

Make an appointment to see your doctor if you have:

Ultimately, research on how the gut microbiome affects our general health and well-being is still growing.

“The bit of research that does exist on gut microbiome to date suggests that this is an area of future emphasis in study,” Purdy says. “Over the next few years, we will really start to see more knowledge about the importance of the gut microbiome emerging, as well as how it impacts our overall health and specific medical conditions.”