“Patients taking probiotics for Crohn’s, ulcerative colitis, or IBS should consider stopping,” says Grace Su, MD, a professor at the University of Michigan in Ann Arbor and the chair of the panel that drafted the guidelines. “The supplements can be costly, and there isn’t enough evidence to prove a benefit or confirm lack of harm.” Probiotics are microscopic organisms — including certain bacteria and yeast — that live in the digestive tract and are also found in a variety of foods and dietary supplements. The new guidelines mark the first time that the AGA has issued clinical recommendations on the use of both single-strain and multistrain probiotics to treat a wide range of gastrointestinal diseases.
How Probiotics Became So Popular
The guidelines come as a growing number of American adults are taking probiotics. According to a 2012 National Health Interview Survey, about four million U.S. adults and 300,000 children reported using probiotics in the previous 30 days. Probiotics usage quadrupled from 2007 to 2012, according to the National Center for Complementary and Integrative Health (NCCIH), and they are the third most commonly used dietary supplement after vitamins and minerals. When the AGA panel reviewed research on the health effects of probiotics, they found few high-quality studies and insufficient evidence to support probiotics for most gastrointestinal conditions. There were, however, exceptions where the evidence showed a potential benefit for probiotics, provided patients read the labels very closely to ensure they were taking the exact type of probiotics recommended by the AGA.
Preemies May Benefit From Certain Probiotics
One of these exceptions is premature and low-birth-weight babies, who may have a lower risk of necrotizing enterocolitis, a common and serious condition that develops when tissue in the intestines gets inflamed or injured, if they take certain multistrain probiotics. For these vulnerable newborns the right mix of probiotics is also associated with shorter hospital stays and a lower risk of death. For these newborns, the AGA recommends several specific combinations of probiotics, such as a mix of Lactobacillus and Bifidobacterium. The quality of evidence for this use of probiotics is moderate to high, according to the AGA. “The fact that a wide variety of preparations — although certainly not just anything that calls itself a ‘probiotic’ — offer benefit suggests some fundamental mechanisms underlying these effects,” says Alexander Khoruts, MD, the coauthor of an editorial accompanying the AGA clinical guidelines published in Gastroenterology and a professor in the division of gastroenterology, hepatology, and nutrition at the University of Minnesota in Minneapolis. It’s possible that certain combinations of probiotics help stimulate faster development of the intestines in premature babies, Dr. Khoruts says. This might, in turn, improve digestion and reduce feeding problems so that these babies are able to gain weight.
Probiotics Might Help With Pouchitis Remission
Adults and kids with pouchitis, a complication after surgery for ulcerative colitis, may also benefit from certain probiotics, the AGA says. One eight-strain combination of probiotics in particular may help maintain remission for these patients, although the AGA also says this recommendation is conditional and the quality of the evidence is low. “This is hardly an endorsement,” Khoruts says. “It means that providers should have very low confidence that probiotics would help pouchitis.”
Probiotics With Antibiotics
The AGA recommends against probiotics for kids who go to the emergency room with acute gastroenteritis and diarrhea, even though probiotics are often dispensed in this situation. For many other situations, the AGA recommends against the use of probiotics outside the context of a clinical trial because there’s not enough evidence that they’re safe or effective. “Probiotics have a lot of potential in helping patients with IBS, ulcerative colitis, and Crohn’s disease, but at the moment there is not enough information to support this,” Dr. Su says.
Probiotics Aren’t Tested Like Prescription Drugs
Part of the problem with considering probiotics as a treatment for specific medical conditions is that these products can reach the market without going through the same type of rigorous clinical trials required for prescription drugs, says Robert Britton, PhD, the coauthor of an editorial accompanying the AGA guidelines and a professor at the center for metagenomics and microbiome research at Baylor College of Medicine in Houston. Probiotics typically reach the market because they’ve been cleared as safe by the U.S. Food and Drug Administration (FDA) for use in food fermentations, but “many of the probiotics on the market were never initially selected on a scientific or medical basis for the disease they are used to treat,” Dr. Britton says. Most probiotics are regulated by the FDA as food ingredients or dietary supplements and not as prescription drugs. Dietary supplements don’t require FDA approval before they’re sold. Companies are supposed to get FDA approval to make health claims about probiotics, such as statements about reducing the risk of disease. Often, probiotics that the market has certified as safe for use in food fermentation by the FDA are cheap and easy to grow in industrial fermenters, and are viable in pill form on store shelves, Britton says. But because supplements aren’t as closely regulated as prescription drugs, it’s still possible for products on store shelves to be dangerous or unsafe, or contain ingredients other than the bacteria on the label, Britton adds. “It’s important to note that no probiotic is approved by the FDA to prevent or treat a disease,” Britton cautions. Patients shouldn’t be swayed by vague health claims like “improves digestion” or “balances gut flora” that they see when they peruse the probiotics section on store shelves, says Khoruts. “These are basically meaningless statements that sound good but have little science to support them,” Khoruts says.
Probiotics in Fermented Foods
Supplements aren’t the only way to get probiotics. A diet rich in fermented foods like yogurt, kimchi, and sauerkraut can also increase the diversity of healthy bacteria in the gut and boost the immune system, according to a study published in July 2021 in Cell. This study randomly assigned 36 healthy adults to follow a diet rich in either fermented or high-fiber foods for 10 weeks. With the fermented foods diet, levels of 19 proteins linked to inflammation decreased in blood and stool samples, suggesting the promotion of a healthier mix of bacteria in the gut. None of these proteins decreased with the high-fiber diet rich in legumes, seeds, whole grains, nuts, fruits, and vegetables. “This is a stunning finding,” says the senior study author, Justin Sonnenburg, PhD, an associate professor of microbiology and immunology at Stanford University. “It provides one of the first examples of how a simple change in diet can reproducibly remodel the microbiota across a cohort of healthy adults.” Larger, longer trials are needed to confirm this finding and figure out exactly why fermented foods might promote a healthy gut, says Khoruts. Fermented foods contain both probiotics and prebiotics, and it’s not yet clear which aspect of these foods may be most beneficial, he said. But there isn’t a downside to consuming these foods as part of a balanced diet. “In my own clinic I usually encourage patients to consume more fermented foods,” Khoruts says. “After all, it is an ancient and time-tested way to preserve the nutritional value of foods without excessive processing and chemical preservatives.”
