American College of Gastroenterology
Advancing Gastroenterology, Improving Patient Care

Probiotics for the Treatment of Adult Gastrointestinal Disorders


  • What are Probiotics?

    The World Health Organization say that probiotics are "live microorganisms which when administered in adequate amounts confer health benefits on the host," you may know theses as germs or bugs. Good types of these bugs called bacteria or yeast live in our guts without making us sick and can even help our bodies be healthy. When bad bugs grow more there than good bugs, it can make you sick. You can eat things with good bugs in them or take pills that have them to help you be healthier

  • How do Probiotics Work?

    Probiotic pills are made to get the bugs through the stomach acid and into the small or large bowels. Here they can grow and help you. We do not really understand how these help, but it may make it hard for bad bugs to live in your guts. When bad bugs grow too much, they can cause you to have gas, belly swelling, or diarrhea. Some good bugs help your get more infection-fighting cells in the bowels and others keep bad bugs from getting out of your guts and into the rest of your body.

  • Are All Probiotics the Same?

    There are a lot of different types of probiotic pills and some work better than others. Some have many types of good bugs and some have only one kind. They can also have a few bugs or a bunch of them. We do not really know if one type is better than another.

  • How do I Know What Type Will Make Me Feel Better?

    The best way to identify an appropriate supplement is to consult with your primary care doctor or gastroenterologist. Many of the probiotics available for purchase have never been scientifically tested and are not regulated by the Food and Drug Administration (FDA). Thus, there is no way to determine whether or not the supplement is beneficial or if the product is safe. Therefore, it is difficult for individuals to identify appropriate products for their specific sets of symptoms or diagnosed clinical illnesses. Many trials have been performed assessing the benefits of probiotics for treating gastrointestinal illnesses. Some have identified beneficial preparations for treating individual disorders, while others have yielded conflicting results. Overall, there is general agreement that the data from these studies has to be interpreted in the context of each individual disorder. The following are disorders with studies suggesting potential benefits for probiotics.

    Irritable Bowel Syndrome (IBS):Probiotics have been tested the most for IBS and seem to help. Some probiotics seem to help people with IBS and others do not seem to help. The bugs that seem to help the most are called Bifidobacterium and Lactobacillus. Your bowel doctor can help you to know which might help you.

    Antibiotic Associated Diarrhea (AAD): A lot of scientific test show that you can have less diarrhea while you take antibiotics, if you take probiotics at the same time. The bugs that seem to help the most are Saccharomyces boulardii (S. boulardii), a yeast, and Lactobacillus rhamnosus GG.

    Infectious Diarrhea: Scientific tests have shown that giving good bugs can help diarrhea that is caused by bad bugs. We do not really know what types of good bugs help the most though.

    Clostridium difficile Associated Diarrhea (CDAD): It does not really seem that probiotics can help much in fighting diarrhea caused by this infection.

    Inflammatory Bowel Disease (IBD): Scientific tests seem to show that that probiotics may help in some types of IBD.

    • Crohn's Disease (CD): It does not really seem like probiotics help people that have Crohn’s.

    • Ulcerative Colitis (UC):  It seems like two probiotics called VSL#3 and E. Coli Nissle 1917 may help people with Ulcerative Colitis.

    • Pouchitis:  A lot of people with ulcerative colitis will end up having to get their large bowel removed. Their surgeons will use part of the small bowel to make a pocked where poop can sit. This lets people be able to wait a bit to have a bowel movement. This pocked is called a pouch and can get inflamed, cause people to poop more, and pass blood or mucus. About 20% to 50% of people with a pouch will get this in the first year after their operation. We usually treat this with antibiotics, but it can come back a lot. A few scientific tests show that VSL#3 given to people soon after their surgery can help stop them from getting this problem.
  • How Long Should I Continue Taking My Probiotic if it Works?

    We do not really know how long it is OK to take probiotics. You should talk with your bowel doctor about whether to keep taking them or not.

  • Are Probiotics Safe?

    We think that they are safe and people have been using them for more than 100 years, without much trouble. The government does not check probiotics for whether they are safe or not, so it is good to be careful when taking them. People with bad health should definitely speak to their doctor before taking probiotics, as they can be dangerous for them sometimes.

  • Are Probiotics the Same as Prebiotics?

    No. Prebiotics are stuff in food or pills that makes your own good bugs grow instead of giving you more good bugs. Your body cannot break these down and it is left as food for the good bugs in your bowels.

Author(s) and Publication Date(s)

Darren M. Brenner, MD, Northwestern University, Feinberg School of Medicine, Chicago, IL – Published July 2011.

Updated by Chien-Huan Chen, MD, PhD, Washington University School of Medicine, St. Louis, MO, 2020

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