Millions of friendly bacteria live in our intestines. They’re essential to digestion. But diarrhea can throw the microbes in your gut off balance. Probiotics, which are doses of helpful bacteria or yeasts, may help get things back on track.
One source of probiotics you know about is yogurt, which is made by adding bacteria to milk. The same microbes may help keep your intestines healthy. Dozens of other kinds may have health benefits, too.
Not all probiotics help diarrhea. And probiotics help only certain types of diarrhea. So which ones can help and when?
Kids and Diarrhea
Some of the best proof that probiotics work comes from studies of diarrhea in children, especially cases caused by rotavirus.
Probiotics might cut bouts of infectious diarrhea by half a day to about 2 days.
Some research shows that the bacteria strains most likely to help are Lactobacillus rhamnosus, Lactobacillus reuteri, and the probiotic yeast Saccharomyces boulardii, although other strains might be useful. A mix of a few different probiotics may also treat this type of diarrhea.
Diarrhea From Antibiotics
Antibiotics kill the bad germs in your body that make you sick, but they also kill the good bacteria. This can disrupt the normal balance in your intestines, leading to diarrhea. It’s common for 10% to 30% of people taking these medicines.
Studies of both children and adults have shown that probiotics taken before and with antibiotics might lower the risk of diarrhea. Saccharomyces boulardii and some strains of lactobacillus can work.
Travelers often come down with diarrhea caused by bad food or water. Cases can last a month or longer.
There’s no hard proof probiotics work for this condition. A 2007 report found they helped travelers avoid this kind of diarrhea. But other studies have shown that they don’t help. The strongest evidence pointed to benefits from Saccharomyces boulardii, Lactobacillus acidophilus, and Bifidobacterium bifidum.
Diarrhea Caused By C. difficile
Infection with C. difficile bacteria causes severe and sometimes life-threatening diarrhea and inflammation in the colon, called colitis. Probiotics may keep you from getting this germ. And there’s some evidence they might stop the condition from coming back. That’s important, since repeat infections become hard to control.
Scientists have done many studies of Saccharomyces boulardii against this type of bacteria. It appears to help, especially when combined with lactobacillus strains.
Inflammatory Bowel Disease
Probiotics may help treat ulcerative colitis, a form of inflammatory bowel disease (IBD). Some studies show probiotics may also help Crohn's disease, the other form of IBD, but the results aren’t as strong.
Where to Find Probiotics
Most health food stores stock dozens of brands of probiotic foods and supplements, like yogurts or dairy drinks, capsules, powders, and liquids.
Look for probiotics with a specific type of bacteria that’s been tested and found to work. Choose products that say that they’re viable “through end of shelf life” rather than “at time of manufacture.”