The bacterium Lactobacillus (reuteri L. reuteri), is a naturally occurring gut flora in mammals. Not all mammals posses the bacterium, however, so it can also be taken as a dietary supplement. The potential health benefits and medicinal uses of Lactobacillus reuteri have been investigated since its classification as a distinct species in 1980. These benefits and medicinal uses include antibacterial properties within the gut, defense against infection, prevention of tooth decay, and treatment of diarrhea. Both the bacterium designation — reuteri — and the antimicrobial substance that it produces — reuterin — are named after the German microbiologist who originally differentiated the bacterium from other citric acids, Gerhard Reuter.
As it possesses the ability to produce the antibiotic substance reuterin, Lactobacillus reuteri is known to inhibit the growth of fungus and yeasts in the gut and the Escherichia coli (E. coli) bacteria in the gastrointestinal tract. In addition, the quantity of reuterin required to destroy the so-called bad bacteria present in the gut is approximately 20% to 25% of the dose that would be harmful to good gut flora. This allows Lactobacillus reuteri to control irregularities in the gut by killing harmful bacteria while not harming the required beneficial bacteria. The bacterium is also known to be present in breast milk and is passed on to the infant during feeding.
Medicinal uses of Lactobacillus reuteri are based in the capacity of the bacteria to control gut flora, thereby balancing the immune system and fighting potentially harmful infections. Through this use, the bacteria can be prescribed to assist with diarrhea, particularly in children. Regular intake of the bacteria as a dietary supplement can prevent diarrhea-related illness from being contracted. The effect of the bacteria on diarrhea has been found to be related to the administered dose — increased Lactobacillus reuteri intake will increase the rapidity of recovery.
The bacterium Streptococcus mutans (S. mutans) is a key contributor to tooth decay. Tests have shown that L. reuteri is one of the only probiotic bacteria that is capable of blocking the effects of the harmful bacteria. By colonizing the mouth with this bacterium, it is thought to be possible to prevent gum disease. Positive effects on gingivitis have also been recorded through the use of the bacteria. This helpful bacterium is also known to reduce the severity of bacterial translocation — often referred to as leaky gut syndrome — which can lead to serious illnesses such as sepsis.