Bacteria tends to get a bad rap — but the truth is, there are some types that are helpful to the body, including probiotics. These “good bacteria” and other live microorganisms can be found in certain fermented foods and in probiotic supplements. Probiotics can be similar to the microorganisms that live in the gut, and when taken in adequate amounts, might help some people with certain digestive issues, according to the National Center for Complementary and Integrative Health (NCCIH).

Probiotic supplements have become increasingly popular over the last two decades. “The research on probiotics has exploded over the past 15 to 20 years,” says Niki Strealy, RDN, LD, a registered dietitian nutritionist in private practice in Portland, Oregon, who specializes in digestive health. “The more we learn, the more we realize how much more there is to know.”

A report published in February 2019 in The Lancet Gastroenterology & Hepatology stated that while 3.9 million people in the United States regularly take probiotic supplements, these supplements can vary in their effectiveness, since those sold as dietary supplements do not require approval from the U.S. Food and Drug Administration (FDA). Probiotic supplements can be quite different in their strains of bacteria and dosing, making them difficult to compare.

How Probiotics Can Help Digestion

Although researchers are still learning about how probiotics work and at what doses they are effective, probiotics appear to help keep the digestive system in balance and help the body get back on track after a bout with “bad” bacteria, according to the NCCIH. “We know probiotics have a lot of benefits,” says Strealy. “These include improved digestion of lactose; reduced digestive symptoms such as gas, bloating, pain, diarrhea, and constipation; and aiding in carbohydrate digestion and production of certain vitamins.”

Probiotics: Food vs. Supplements

Probiotics can be found naturally in fermented dairy such as milk, yogurt, and kefir and in foods such as fresh kimchi and sauerkraut. It’s great to include these items in your regular diet, but try to keep them cold and unprocessed, as heating these foods can destroy the good bacteria. “Eating fermented foods is a way of bringing in beneficial microbes to the digestive tract; however, it is difficult to know how many microbes you are consuming,” Strealy notes.

For those who have digestive problems, Strealy often recommends trying a probiotic supplement. If you take a probiotic supplement for specific symptoms and don’t see improvements after four to six weeks, Strealy suggests trying a different brand that has different strains of microbes. “Lactobacillus, Bifidobacterium (bacteria), and Saccharomyces boulardii (yeast) are generally safe,” advises Strealy.

Digestive Issues That May Benefit From Probiotics

Although more research is needed to determine the best strain(s) for each condition, and the most effective dosage, preliminary research shows that probiotics may be helpful when dealing with a variety of gastrointestinal issues, such as:

Diarrhea: In a meta-analysis last updated in 2019, researchers from the Cochrane Collaboration found that in cases of acute diarrhea, taking probiotics helped diarrhea go away one day faster than it would otherwise. “Probiotics can slow gastrointestinal contraction to stop diarrhea,” explains Strealy.

Constipation: In a meta-analysis published in July 2017 in the Archives of Gerontology and Geriatrics, researchers found that taking probiotics improved constipation in elderly people by up to 40 percent. “Probiotics can alleviate constipation by decreasing transit time and making stools softer and easier to pass,” says Strealy.

Gassiness, cramping, and irritable bowel syndrome (IBS): According to a study published in February 2018 in Alimentary Pharmacology & Therapeutics, probiotics can relieve lower gastrointestinal symptoms in people with IBS — including pain and cramping, bloating and gas, and diarrhea.

Lactose intolerance: A study published in June 2019 in Critical Reviews in Food Science and Nutrition found an overall positive relationship between probiotics and lactose intolerance, although some strains of probiotics were more effective than others.

Inflammatory bowel disease (IBD): IBD encompasses both Crohn’s disease and ulcerative colitis, digestive conditions that can cause symptoms such as pain, diarrhea, and bloody stools. A study published in May 2018 in Alternative Therapies in Health and Medicine found that probiotics may help rebalance gut flora from inflammatory to anti-inflammatory. However, more research is needed on what strains and at what dosage probiotics can help IBD.

During and after antibiotics: Diarrhea is a common side effect when people take antibiotics, because the medication kills off both good and bad bacteria in the gut. A meta-analysis published in December 2017 in the journal Antibiotics found that those who took probiotics along with antibiotics were about half as likely to experience antibiotic-associated diarrhea.

Antibiotic use can also result in an infection in the large intestine from a bacteria called Clostridioides difficile (C. diff.), which can cause diarrhea as well. A meta-analysis published in December 2017 in the Cochrane Database of Systematic Reviews concluded with moderate certainty that taking probiotics along with antibiotics can reduce the risk of diarrhea caused by C. diff., and that taking probiotics along with antibiotics is safe for most, except in cases where people have very weak immune systems.

If you want to try a probiotic supplement to ease a particular digestive symptom, a dietitian can help you select one from a reputable brand. Alternately, Strealy suggests visiting the International Scientific Association for Probiotics and Prebiotics for information on how to choose a probiotic that's been researched for the condition you're trying to treat, such as IBS.

Although it may take some time to find what works for you, probiotics can be a safe way to help keep your digestive system on an even keel.

By Erica Patino on EverydayHealth