Medically Reviewed By William C. Lloyd III, MD, FACS

What are probiotics?

Probiotics are live microorganisms that have health benefits. It’s common to think of microbes as bad because they can cause infections. However,  probiotics are actually beneficial microbes. They are the same or similar to microbes that normally live on or in your body. They perform functions that help your body work properly. This is symbiosis, or a symbiotic relationship. Probiotics are available in supplements and certain foods, such as yogurt, kimchi, and other fermented foods.

The main types of probiotics are bacteria from the genus Bifidobacterium and the genus Lactobacillus, and yeast from the species Saccharomyces boulardii. A common use of probiotics is to promote digestive health. Microbes in your gut help decrease growth of disease-causing ones. They also make vitamins and help your body digest food. Probiotics may also benefit people with allergies, urinary tract problems, and skin conditions.

What are the benefits of probiotic supplements and foods?

There are many types and combinations of probiotics. The different probiotic supplements have different effects. To get the benefits you want, check the product labeling. Also, talk with your doctor about the benefits you can expect.

Potential probiotic benefits may include helpful effects for the following conditions:

There is also some evidence probiotics may help lower cholesterol and reduce cholesterol levels. In addition, children with stomach pain and colicky babies may benefit from probiotics. Talk with your pediatrician before using probiotics for kids.

Who recommends probiotics?

Your doctor is a good place to start if you are interested in probiotics. This could be your primary care doctor or a specialist that manages the condition you are looking to treat. For example, a gastroenterologist may have the most experience using probiotics in digestive disorders. Dietitians and pharmacists can also be valuable resources for finding the right product.

How are probiotics packaged and labeled for use?

The FDA (Food and Drug Administration) considers probiotics to be dietary supplements. This means the agency does not regulate them the way they do prescription and over-the-counter drugs. Companies that make a dietary supplement don’t have to prove the claims on the label. So be cautious in choosing a probiotic brand. Talk with your healthcare provider for help choosing the right one.

In general, look for a product from a reputable manufacturer. Also, look for a certification seal from USP, DSVP, CL or NSF. These are reliable stamps that supplement companies voluntarily seek. The organizations behind these stamps verify the content claims are true. A certification seal is a good sign that the probiotic accurately contains what is says it contains, the stated quantity of microbes, and isn’t contaminated. Keep in mind, this doesn’t guarantee safety or effectiveness. Beware of misleading seals that look official, but aren’t.

When you are looking at a probiotic label, it should tell you the probiotic group (or genus), the species, and the strain of the species, ideally. Strain is important because some health benefits can be strain-specific. If the strain is not on the label, try contacting the company or work with a healthcare provider with experience using probiotics.

The label should also tell how many live microbes are in the product. The standard way to express this is CFUs (colony forming units). You may also find microbes listed with a weight, such as mg (milligram). This is due to the current the FDA requirement of using weights in the Supplement Facts section of a label. However, weight is not useful information for probiotics. The FDA is currently evaluating the best way to express supplement facts for probiotics.

Doses of live microbes or CFUs vary depending on the specific strain and reason for taking it. Talk with your healthcare provider for guidance on dosing.

Finally, check the label for storage instructions. Some products require refrigeration, while others do not. Also, check the use by date or expiration date. Because probiotics are living organisms, they have a limited shelf life.

What are the risks and potential side effects of probiotics?

Probiotics are likely safe for most people. Probiotic side effects are generally few, mild and temporary. Side effects are usually digestive in nature, such as gas or bloating. However, probiotics may cause problems for people with certain medical conditions, such as a weakened immune system. They can also trigger allergic reactions in some people and may interfere with certain medicines. Always talk with your doctor before starting a supplement, including probiotics. If a probiotic supplement is not right for you, ask about the safety of eating food sources of live microbes, such as yogurt.

Was this helpful?
  1. Bifidobacteria. MedlinePlus, U.S. National Library of Medicine.
  2. Dietary Supplements: What You Need to Know. U.S. Food and Drug Administration.
  3. Health Benefits of Taking Probiotics. Harvard University.
  4. Lactobacillus. MedlinePlus, U.S. National Library of Medicine.
  5. Policy Regarding Quantitative Labeling of Dietary Supplements Containing Live Microbials: Guidance for Industry – DRAFT. U.S. Food and Drug Administration.
  6. Probiotics. American Academy of Family Physicians.
  7. Probiotics. American Gastroenterological Association.
  8. Probiotics. Cleveland Clinic.
  9. Probiotics: In Depth. National Center for Complementary and Integrative Health.
  10. Saccharomyces boulardii. MedlinePlus, U.S. National Library of Medicine.
  11. Using Dietary Supplements Wisely. National Center for Complementary and Integrative Health.
  12. What Are Probiotics? Mayo Foundation for Medical Education and Research.

Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2021 Feb 13
View All Digestive Health Articles
THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.