What Are Prebiotics? Health Benefits, Risks, More

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On July 16, 2025

Research is ongoing to better understand prebiotics and the gut microbiome as a whole. But there is growing evidence that prebiotics have various potential benefits, including supporting a healthy immune system, improving blood sugar control, reducing the risk of colon cancer, and improving intestinal absorption of dietary calcium.

“The research is promising but evolving. There is strong evidence for the importance of gut health and that prebiotics can help to encourage a diverse gut microbiome,” says Alyssa Pacheco, RD, owner of The PCOS Nutritionist Alyssa in the Boston area.

“However, many studies are short term and focus on either small sample sizes or specific populations, such infants or people with irritable bowel syndrome (IBS).”

Some potential health benefits of prebiotics include:

May Support Regular Bowel Movements

Prebiotic foods contain dietary fiber that helps promote motility (the movement of food through the gastrointestinal tract) and regular bowel movements, says Shelley Balls, RDN, owner of the online nutrition service Fueling Your Lifestyle, based in Smoot, Wyoming.

“Prebiotic fibers also promote the production of short-chain fatty acids that can improve regularity,” she adds.

However, she says that research in this area is still lacking and more robust, long-term, double-blind, randomized controlled human trials are needed.

May Support a Healthy Immune System

Prebiotics may influence immune health through their impact on the gut microbiome, which plays a key role in regulating immune responses, says Lance Uradomo, MD, interventional gastroenterologist at City of Hope in Irvine, California.

“This is an important area of study,” Dr. Uradomo says. “But much of the current evidence is still emerging, and more targeted human studies are needed to establish how this might apply in clinical settings.”

May Lower Inflammation

Prebiotics’ influence on the gut microbiome may also help reduce inflammation, as many SCFAs can have anti-inflammatory properties, Balls says.

That said, Balls notes that research in this area is still lacking and that more large, high-quality human studies are needed to determine how prebiotics may impact inflammation.

May Improve Anxiety and Depression Symptoms

The gut microbiome plays an important role in the production of neurotransmitters (chemical messengers) between the gut and brain that affect factors like mood and sleep.

By supporting a healthy gut, prebiotics may help increase levels of these neurotransmitters (including serotonin and dopamine) and, in turn, could improve anxiety and depression symptoms.

Still, more research is necessary, as most studies have been small, of short duration, and focused on women or people already taking medications, says Zachary Spiritos, MD, a neurogastroenterologist at UNC Health in Clayton, North Carolina, and founder of EverBetter Medicine, a telemedicine platform serving Illinois and North Carolina.

“We need larger and longer studies that include people from diverse backgrounds and track not just mood but also what is happening in the gut,” Dr. Spiritos says.

May Suppress Appetite

Through their impact on the gut microbiome, prebiotics may help stimulate the production of appetite-suppressing hormones like glucagon-like peptide-1 (GLP-1) while decreasing levels of ghrelin, the hormone that signals to your brain that you’re hungry, Balls says.

“The research behind prebiotics and appetite suppression is still very new, and we need more robust long-term, double-blind, randomized controlled human trials to learn more about the intricacies of this relationship,” she explains.

May Help Regulate Metabolism and Blood Sugar

Prebiotics may help control blood sugar by slowing down the rate at which your body metabolizes and absorbs carbohydrates, Balls says.

Moreover, because the gut microbiome affects metabolism, blood sugar management, and insulin sensitivity, prebiotics may influence these factors by promoting the growth of healthy bacteria in the gut, Balls adds.

“However, this area of research is still fairly new, and more robust, long-term, double-blind, randomized controlled human trials are needed,” she says.

Some “promising” research also suggests that prebiotics could help with managing or preventing type 2 diabetes via its influence on metabolic health, blood sugar, inflammation, and insulin sensitivity, says Raj Dasgupta, MD, associate program director of the internal medicine residency program at Huntington Memorial Hospital in Pasadena, California, and chief medical adviser for Garage Gym Reviews.

For example, in a review and analysis of 58 clinical trials involving 3,835 participants, researchers found prebiotics to have a notable positive impact on people with type 2 diabetes.

Specifically, taking prebiotic supplements for 8 to 12 weeks reduced HbA1C (average blood sugar) levels, helped maintain stable glucose levels, and improved the function of beta cells, which make and release insulin.

That said, most studies to date have been small, short-term, or done in very specific populations, Dr. Dasgupta notes. Larger, longer-term clinical trials on more diverse populations are needed, he says.

“The research is encouraging, but we need stronger evidence before prebiotics become a standard part of diabetes care,” Dasgupta explains. “For now, they could be a helpful addition to a healthy lifestyle, especially when paired with a balanced diet and other proven strategies.”

May Decrease the Risk of Colon Cancer

Studies have shown that prebiotics may help reduce the risk of colon cancer by supporting a healthy gut microbiome and producing anti-inflammatory compounds that protect colon cells, but more research is needed, Uradomo says.

“While animal and lab studies have shown potential mechanisms, large-scale, long-term studies in human populations are still needed to better understand how prebiotics could contribute to cancer prevention,” he explains.