What Are Probiotics?

A dietary supplement that helps balance your gut bacteria

Probiotics are live microorganisms (bacteria or yeast) shown to have health benefits. They're thought to increase the level of "good" bacteria in your intestines.

These "good" bacteria are thought to enhance health by supporting your digestive and immune systems.

Probiotics are available in supplement form or in foods and drinks.

This article will look at why probiotics are needed, their possible health benefits, conditions they may help treat, and how to find the right one for you.

Probiotic supplements in blister packs
Juergen Bosse / Getty Images

Why They're Needed

Several aspects of modern society can mess with the delicate balance of good bacteria in your gut. They include:

  • Antibiotics
  • Too little plant-based food
  • Refrigeration
  • Improved sterilization of foods

What we don't yet know is whether probiotics actually can improve the health of your gut flora, as is suspected.

Possible Benefits

Many types of probiotics are on the market. Two of the major types are lactobacillus or bifidobacterium.

Each type has a variety of strains. Although it is not confirmed, some scientists think different strains have different effects.

Probiotics are being studied for a wide range of health benefits. They're theorized to:

  • Boost the immune system
  • Help ward off infection
  • Kill off harmful bacteria
  • Improve the strength thickness of the mucus lining the intestines


Probiotics are live microorganisms believed to have beneficial effects on gut flora. Modern diets and medications may throw gut flora out of balance.

Different types and strains are available and each may have its own set of benefits.

Probiotics are theorized to boost the immune system, keep you from getting sick, and improve intestinal function.

Conditions Probiotics May Treat

Manufacturers make a lot of claims about what conditions probiotics can help treat. But research often doesn't back up those claims.

It's hard to conduct quality research on probiotics due to the many strains available. Some studies show mixed results as well. Research is ongoing.

However, some research supports probiotic use for:

Additionally, preliminary research indicates probiotics may help prevent:

AGA Guidelines

The Amerian Gastroenterology Association (AGA) recommends these probiotic strains for preventing C. difficile infection:

  • Single strain: S boulardii
  • 2-strain combination: L acidophilus CL1285 and Lactobacillus casei LBC80R
  • 3-strain combination: L acidophilusLactobacillus delbrueckii subsp bulgaricus, and Bifidobacterium bifidum
  • 4-strain combination: L acidophilusL delbrueckii subsp bulgaricusB bifidum, and Streptococcus salivarius subsp thermophilus.

How to Choose a Probiotic Supplement

If you decide to use a probiotic supplement, be sure to read the label carefully. You're looking for:

  • A supplement containing live strains of the bacteria or yeast
  • Guarantees that they're alive at the time of use (not the time of manufacture)

The United States has no federal standards for probiotic supplements. Therefore, you run the risk of buying a product with no guarantees that:

  • The product contains what it's supposed to
  • The strains are alive
  • The product is free from unhealthy ingredients

It's best to choose a brand-name probiotic that has research backing its effectiveness. Some of these brands include:

  • Align
  • Culturelle
  • Florastor
  • VSL#3

Remember probiotics are live organisms. Use them before the expiration date. Check package instructions for storage instructions.

Some probiotics need to be refrigerated. Others should be stored in a cool, dry place.

Be sure to involve your healthcare provider in your decision to use probiotics.


Probiotics may help treat many digestive disorders (IBD, IBS, SIBO), acute viral infections in children, and mouth diseases including gingivitis and periodontitis. They may also prevent asthma in children, dental cavities, and C. difficile infection.

When choosing a probiotic supplement, read the label too make sure you're getting live strains. Because supplements aren't regulated, choose name brands with research to back them up.


Most probiotic studies have shown few, if any, negative side effects. Still, keep in mind research is still in an early phase.

Probiotics may pose some risk to people with certain health conditions or a compromised immune system. As with any supplement, it's essential that you talk to your healthcare provider before taking it.


Probiotics are believed to increase the "good" bacteria in your gut, improve digestion, and support the immune system. Things that can throw off that balance include antibiotics and diets without enough plant-based food.

Probiotics have some evidence showing they can help treat or prevent digestive disorders, several causes of diarrhea, and certain infections.

When choosing a probiotic supplement, look for respected brands that guarantee a live strain. Be sure to store it correctly.

Probiotics may not be safe for everyone. Talk to your healthcare provider before taking them.

A Word From Verywell

If you have a digestive or immune-related condition probiotics are thought to treat, supplements may be a welcome addition to your regimen.

Get your healthcare provider's okay, buy a quality supplement, and then keep your eyes open for any negative side effects. Remember that natural doesn't always mean safe.

Was this page helpful?
6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Shi LH, Balakrishnan K, Thiagarajah K, Mohd Ismail NI, Yin OS. Beneficial Properties of ProbioticsTrop Life Sci Res. 2016;27(2):73–90. doi:10.21315/tlsr2016.27.2.6

  2. What are probiotics and can they aid GI health? American Gastroenterological Association.

  3. Probiotics. Fact Sheet for Health Professionals. National Institutes of Health. Office of Dietary Supplements. June 26, 2019

  4. Su GL, Ko CW, Bercik P, et al. AGA clinical practice guidelines on the role of probiotics in the management of gastrointestinal disordersGastroenterology. 2020;159(2):697-705. doi:10.1053/j.gastro.2020.05.059

  5. American Gastroenterological Association. Choosing the right probiotics.

  6. National Institutes of Health. National Center for Complimentary and Integrative Health. Probiotics: What you need to know. . August 2019

Additional Reading