Prebiotics: what are the health benefits?

Our bodies are filled with microorganisms. While that might sound scary, they’re a healthy part of our system that live happily on our skin and in our digestive tracts. 

Prebiotics aren’t living organisms like probiotics but are important in supporting the “good” bacteria in our guts. There have been lots of studies about the health benefits of prebiotics. Let’s dive in.

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Prebiotics are a type of dietary fiber that serve as food for friendly bacteria that live in our intestines. Specifically, prebiotics are non-digestible compounds mainly found in carbohydrates. 

Because we can’t digest them, our bodies can’t use prebiotics in their original form. Luckily, our digestive systems are teeming with beneficial bacteria that process prebiotics for us. But prebiotics are more than just a source of calories (Gibson, 2017; Davani-Davari, 2019).

When digested by bacteria, prebiotics are turned into products that support our digestive systems and other parts of the body (Fortuna, 2021). Sounds pretty great, right? The catch is we can’t digest nutrients like these ourselves—we need gut bacteria to digest and break them down for us via a process called fermentation. 

The healthy bacteria and yeast in our guts feed on prebiotic nutrients present in dietary fiber. These nutrients are fermented or broken down by microorganisms into smaller compounds, most of which are known as short-chain fatty acids. 

Fermentation products are believed to improve gut health; they also get released into the bloodstream and circulate throughout the body. This is thought to provide overall health benefits like improving calcium absorption and regulating immune function (Davani-Davari, 2019; Carlson, 2018).

They sound similar and often cause confusion, but prebiotics and probiotics aren’t the same things. Probiotics are living microscopic organisms found in fermented foods––like yogurt, sauerkraut, kimchi, and kefir––and are available as dietary supplements.

Prebiotics are not living organisms. They are a component of certain high-fiber foods that serve as a nutrient source for beneficial microorganisms living in our gut (Davani-Davari, 2019).

Scientists are still learning about the health benefits of prebiotics, with more than a hundred clinical trials investigating uses for prebiotics. 

Researchers are also testing prebiotics to see if they can help with medical conditions like type 1 diabetes, Parkinson’s disease, multiple sclerosis, and schizophrenia (ClinicalTrials.gov).

Scientists have also evaluated the role of prebiotics in other bodily functions like the ones below.

• Maintaining gut health: Laboratory studies show that the fermentation products produced from prebiotics may improve the integrity of the gut barrier, which keeps waste and bacteria from entering the bloodstream (Suzuki, 2008). Prebiotics also keep populations of friendly gut microbiota like Bifidobacteria and Lactobacilli balanced (Gibson, 2005).

• Increasing calcium absorption: In some studies, prebiotic supplements helped increase the absorption of calcium, a mineral that supports strong bones and other vital functions (Coudray, 1997).

• Regulating the immune system: One study found that children who had prebiotic formula as infants had fewer infections requiring antibiotics and a reduced frequency of allergy-related conditions than those who didn’t take prebiotic formula (Arslanoglu, 2008). That said, prebiotic supplements are not recommended for children. Changes to an infant’s diet should be made under the guidance of a pediatrician. 

There’s also evidence that prebiotic supplements play a role in weight management. An analysis found that supplementing with prebiotics and probiotics may promote weight loss and have anti-inflammatory benefits (Ferrarese, 2018). 

Prebiotics are naturally found in low concentrations in a variety of foods. There are many more but familiar food sources packed with prebiotics (Davani-Davari, 2019):

• Asparagus

• Bananas

• Barley

• Beans

• Chicory

• Cow’s milk

• Garlic

• Honey

• Jerusalem artichoke

• Onions

• Peas

• Rye

• Seaweed

• Soybeans

• Sugar beets

• Tomatoes

• Wheat

Foods with resistant starches can have prebiotic effects. Resistant starches are a type of carbohydrate that “resists” getting digested in your small intestine. Instead, resistant starches are digested by gut microbes in the large intestine. Some examples are bread, plantains, grains, pasta, rice, legumes, and potatoes (Patterson, 2020). 

Keep in mind that not all fiber has prebiotics. Fiber is naturally found in many whole grains, vegetables, fruits, and legumes, so while many prebiotic foods contain fiber, not all sources of fiber possess prebiotics (ISAPP, 2020).

There is evidence that a prebiotic supplement may alleviate digestive issues like constipation. Researchers evaluating studies on the topic concluded that treating constipation of unknown cause with prebiotics seemed to help (Naseer, 2020). 

You can try increasing prebiotic foods as a starting point. Consuming about 3–5 grams of dietary prebiotics per day is recommended to see health benefits. If you have persistent constipation, speak with a healthcare professional who can identify the root cause and suggest other treatments (ISAPP, 2020).

There isn’t enough evidence yet to say for sure if anyone needs a prebiotic supplement. There is also no official guidance or a recommended daily intake for prebiotics.

That said, prebiotic supplements do have potential health benefits. But taking a supplement is just one small part of an overall healthy lifestyle. Your best bet for success is staying physically active, consistently choosing nutritious foods, and avoiding things like smoking (Gibson, 2017).

Also, note that industrial manufacturing processes produce higher concentrations of prebiotics than you can reasonably consume through diet alone (Davani-Davari, 2019). 

Little is known about the risks and side effects of prebiotics. It is safe to eat foods that contain prebiotics. However, some people experience bloating and gas from prebiotics, especially if you consume too much. 

If you’re considering a prebiotic supplement for digestive health, it’s a good idea to speak with a healthcare provider or dietitian first. They can help you decide if trying a prebiotic dietary supplement is right for you.

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How we reviewed this article

Every article on Health Guide goes through rigorous fact-checking by our team of medical reviewers. Our reviewers are trained medical professionals who ensure each article contains the most up-to-date information, and that medical details have been correctly interpreted by the writer.

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Current version

April 07, 2022

Written by

Patricia Weiser, PharmD

Fact checked by

Yael Cooperman, MD

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About the medical reviewer

Yael Cooperman, MD, Ro

Yael Cooperman is a physician and works as a Senior Manager, Medical Content & Education at Ro.