Reviewed by: HU Medical Review Board | Last reviewed: March 2023

Probiotics are often used as a treatment for irritable bowel syndrome (IBS).1 Probiotics, also called “good bacteria,” are defined as live microorganisms that are similar to the beneficial bacteria found in the human gut.2

Although the exact cause of IBS is unknown, it is thought to be a combination of factors, with alterations in the muscle movements of the gut, bacterial overgrowth, hypersensitivity, and microscopic inflammation potentially contributing to the condition.4 Probiotics are believed to help restore the gut environment in delivering beneficial bacteria into the gut.1

Although bacteria are often considered as harmful “germs,” there are in fact a number of bacteria that naturally live in the human digestive tract and work in cooperation with the human body, helping it to function properly. Probiotics are the same or similar to these helpful bacteria.3

Research on probiotics in the treatment of IBS

The most well-studied probiotic is Bifidobacteria infantis, which has been proven to reduce the abdominal symptoms of IBS, particularly bloating and bowel function. Other studies have looked at strains of the Lactobacillus and Propionibacterium species.4 In addition, a recent analysis of the research that included multiple probiotics, many administered in combinations, found evidence to support that probiotics benefit people with IBS. But there is no consensus or recommendations on what the optimal strains, combinations or doses are for people with IBS.1

Although their exact action is unknown, probiotics are believed to help IBS by improving the mucosal lining and restoring the gut’s barrier function.1 Probiotics suppress the growth and binding of destructive bacteria in the gut, and they alter the acidity level in the intestines and improve the immune response.4

There is some evidence that various probiotics are helpful in preventing diarrhea and improving symptoms of IBS, but there is no conclusive evidence to determine which probiotics are helpful and which are not. It is also unknown how much of the probiotic people need to take or which people would most benefit from taking probiotics.

In 2020, the American Gastroenterology Association (AGA) released new guidelines for using probiotics. Researchers did not find enough evidence to support the use of probiotics for IBS. They recommend that children and adults with IBS only use probiotics in clinical trials.5,6

Sources of probiotics

Probiotics are available in several formulations. Oral products, including dietary supplements and yogurts, are available at many grocery stores, health food stores, and pharmacies. Other products that deliver probiotics include suppositories and creams.3 It is worth noting that because probiotics are not considered pharmaceutical drugs, they are not currently regulated by the U.S. Food and Drug Administration, and there may be substantial differences in the quality and effectiveness of various brands.3,4 People are encouraged to talk to their doctor or pharmacist about recommended brands of probiotics.

When considering probiotics

Studies have shown that probiotics usually have few side effects, however, the long-term safety data is limited. In healthy people, probiotics have minor side effects, if any. However, in people with other health conditions, such as weakened immune systems, there have been occasional serious complications reported, such as infections.3

Every person reacts differently to different treatments, including probiotics, medications, complementary and dietary changes. Discussing all possible treatment options with a health care professional is recommended.

Other treatment options

The management of IBS symptoms is usually accomplished by a combination of approaches, and determining the best combination for a person may require some trial and error. Besides probiotics, other treatment strategies include adding exercise, making dietary changes, adding fiber, using medication, or trying complementary or alternative medicine.

Before beginning treatment for IBS, tell your doctor about all your health conditions and any other drugs, vitamins, or supplements you take. This includes over-the-counter drugs.

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