By Dr. Mary Ellen Sanders, Ph.D.

Probiotics are live microorganisms that, when administered in adequate amounts, confer a health benefit on the host. For details, see FAO/WHO (2001) and the 2014 update by ISAPP: Expert consensus document: The International Scientific Association for Probiotics and Prebiotics consensus statement on the scope and appropriate use of the term probiotic.


Probiotics are contained in a variety of different products, including foods, dietary supplements, infant formula, medical foods, pharmaceuticals and even devices (such as tampons that deliver probiotics). Evidence for the benefits of probiotics is emerging, but strong evidence for probiotic benefit has been seen with reducing antibiotic associated diarrhea, improving mild to moderate IBS and other digestive symptoms, reduce crying time in colicky but otherwise healthy infants, reducing the incidence and duration of common upper respiratory tract infections and helping manage vaginal infections. Probiotics are also used in some hospitals to help prevent necrotizing enterocolitis in premature infants.

probiotics infographic cropped


Probiotics, like all strategies for helping promote your health, might not work for everyone. People have different diets, the microbes colonizing their gut are specific to each of us and everyone’s physiology is unique. Research often shows that some people respond to a specific probiotic strain and others do not. So if you feel a probiotic is something you’d like to use, one strategy is to try a product for about a month. If you don’t see a benefit, then perhaps it’s not the right one for you.


Probiotics are an active area of research globally. Recent findings show that the live microbes that live in and on our bodies are very important to our health. Probiotics can also contribute to such health benefits.


Additionally, people interested in adding live microbes to their diets are increasingly interested in fermented foods and prebiotics. A word about Fermented Foods. A word about Prebiotics.


About the author: Mary Ellen Sanders, Ph.D. is an expert in probiotic microbiology. She was the founding president of ISAPP and currently serves as its Executive Science Officer. She also consults with companies on microbiological and regulatory issues concerning probiotics.

Choosing a Probiotic Product

Consumer Guidelines probiotic

Match the probiotic to the benefit you want – not all strains are the same. Some helpful guides:


Amounts matter with probiotics.

Be sure the product contains the level of probiotics needed for the intended health benefit.


  • Probiotic counts are reported in CFU (colony forming units) per serving or dose.
  • Probiotic benefits are typically associated with daily consumption and effective doses range from 100 million to several trillion CFU per day, depending on the particular probiotic and benefit.
  • It’s best to take a probiotic at the dose or servings that were tested and shown to be beneficial. Ask the manufacturer if their product delivers an effective dose throughout the end of its shelf life.
  • Because levels of live probiotics can decrease while on the store shelves, products labeled with a live content “at time of manufacture” don’t tell you what you need to know. Look for a product labeled with CFU through the end of its shelf life.
  • Most probiotics should be consumed daily for optimum results.

Probiotics Resources:


  • WGO Handbook on Gut Microbes – including 15 chapters by global experts on microbiomes, gut microbiota and its role in health and disease, probiotics and prebiotics.
  • Gut Check: Exploring Your Microbiome. Archived Coursera course by Prof. Rob Knight. Imagine if there were an organ in your body that weighed as much as your brain, that affected your health, your weight, and even your behavior. Wouldn’t you want to know more about it? There is such an organ — the collection of microbes in and on your body, your human microbiome.
  • See ISAPP’s Resources Page for more information on probiotics, prebiotics, fermented foods, microbiomes, and gut health, including videos and e-learning opportunities