Lactobacillus reuteri:
Commonly-Occurring Beneficial Bacteria Also Used in Probiotic Supplements

Lactobacillus reuteri (L. reuteri) is a species of Lactobacillus bacteria that naturally inhabits the digestive tract, the female vaginal and urinary tracts, and breast milk. 

It is also commonly found in some cultured vegetables (such as those in the picture above), in the intestinal tracts of animals, in meat and dairy products, and in the natural environment.

Since it is so widespread, it should not be a surprise to know that specific effects of these bacteria are strain-specific and cannot be generalized across the whole species. The research below shows both species-wide and strain-specific information.

L. reuteri was originally thought to be part of the L. fermentum species, but it was classified as its own distinct species. It is named after the German microbiologist, Gerhard Reuter, who isolated the first strain from human samples.

Most people have heard either all good things about this species or all bad things; the truth lies somewhere in between the two.

Is L. reuteri Safe?

Because L. reuteri as a species is commonly found in foods, the environment and within us, it is generally regarded as safe. It is on the European QPS (Qualified Presumption of Safety) list. Remember, though, that specific strains have specific actions.

What Does Research on Lactobacillus reuteri show?

Research shows:

  • As a species, it is best known for its ability against pathogenic microbes. Some of you may have heard about the broad-spectrum antimicrobial substance, reuterin.
  • Not all strains of L. reuteri produce reuterin, but that is okay because reuterin production is not the only way that members of this species can have beneficial effects.
  • As a species, it also produces carbon dioxide, ethanol, acetic acid and lactic acid from glucose and so is considered to be obligately heterofermentative.
  • It is also able to survive in low-to-no oxygen environments and to produce hydrogen peroxide under the right conditions.
  • It is able to convert lactose to lactic acid which may help with lactose intolerance.
  • Many strains have been recovered from feces showing the ability to withstand stomach acid and bile acids in the digestive tract.
  • Some strains, such as A1, which was recovered from canine feces, are able to withstand the freeze-drying process with no loss of vitality.

Which Strains of Lactobacillus reuteri are the Most Well-Known?

The most well-known strains of L. reuteri are:


Return to Lactobacillus page
Return to Homepage.

I research studies and share my clinical experience to write this free site to help you find solutions to your problems. As part of that, I recommend products and services that I genuinely believe will be of help to you. If you click on a link to a product/service, I may receive a small commission to support my efforts if you buy something. The item does not cost you more.

Thanks for visiting this site! If you've enjoyed reading this page or have found the information to be useful to you, please "like", tweet about it, or share it so others can benefit, too. You can leave comments below via Facebook or Disqus.

Comment with Facebook!

I'd love to hear your opinion about what you just read. Leave me a comment in the box below! Other commenting options follow the Facebook comments.

Comment with Disqus (including as a guest), Twitter or Google accounts:

If you are one of my many readers without a Facebook account, you can still comment.


Disclaimer: Please note: By law, I cannot provide any personalized recommendations for your specific health concern on this site. The information contained in this site is educational in nature and is not intended as diagnosis, treatment, prescription or cure for any physical or mental disease, nor is it intended as a substitute for regular medical care. Consult with your doctor regarding any health or medical concerns you may have.

Subscribe to my monthly newsletter and receive a free copy of "How to Use Probiotics to Lose Weight and Be Healthier".

To comply with the EU's GDPR data privacy regulation, please subscribe here:


Looking for some quality professional supplements, including probiotics? Check out my online dispensary, as I will be doing reviews of some of these products in the future. Click on the Fullscript picture. (Note: If you were a former Wellevate customer, please switch to Fullscript for a better customer experience. Thanks!)


SiteSell Hosting

Some competitors of SBI (Solo Build It) are posting fake negative reviews of SBI. If you are considering creating your own website business, or if you have a brick-and-mortar business but want an online presence, I highly recommend SBI!