by Marion Nestle
Dec 6 2018

Do probiotics work? Maybe, if you are lucky

The industry newsletter,, regularly posts Special Editions on Probiotics, meaning collections of its articles on the topic.  These promote the benefits—to digestion and many other physiological and mental aspects—of eating healthy bacteria.   But do probiotics really work?  And could they actually be harmful?  See comments below these selected articles.

Two recent articles in Cell raise questions about the benefits of probiotics.

In translation:

  • The murine [mouse] & human gut mucosal microbiome only partially correlates with stool
  • Mice feature an indigenous-microbiome driven colonization resistance to probiotics
  • Humans feature a person-specific gut mucosal colonization resistance to probiotics
  • Probiotic colonization is predictable by pre-treatment microbiome & host features

In further translation:

  • Not everyone responds to probiotics, which means that they may be worth a try and you may get lucky.

And an even more recent article in JAMA Internal Medicine questions whether probiotics might be harmful.  It warns about:

  • The safety of bacteria in probiotic supplements has not been fully established.
  • They can lead to infections and allergic reactions.
  • Probiotic supplements often do not meet manufacturing standards (identity, purity, strength, composition).
  • Introduction of new genes for antibiotic resistance into microbiomes.

The article concludes:

Consumers and physicians should not assume that the label on probiotic supplements provides adequate information to determine if consuming the live microorganism is worth the risk.

What to think about all this?  If you like yogurt, enjoy!  But supplements are another matter.