Lactobacillus reuteri is a probiotic whose benefits have only recently come to light. Originally classified as a strain of Lactobacillus fermentum, it wasn’t until 1980 that L. reuteri was identified as a distinct species of lactic acid bacteria subsequent to research conducted in the 1960s by Gerhard Reuter, for whom L. reuteri was named.
In an article titled “The Lactobacillus and Bifidobacterium microflora of the human intestine: composition and succession,” it was observed by Dr. Reuter that L. reuteri and L. gasseri were the predominant indigenous Lactobacillus species in infants as well as in adults and that the microflora of these bacteria remains stable lifelong.1
L. reuteri Helps Reduce Diarrhea of Varying Causes
Healthy bacteria colonize the gut to help lower the risk of infection, and L. reuteri is no exception. In 40 children aged 6 to 36 months who were hospitalized with acute diarrhea caused mainly by rotavirus infection, daily administration of L. reuteri decreased the mean duration of watery diarrhea compared to a placebo.2 As soon as the second day of treatment, watery diarrhea was present in just 26% of those who received the probiotic compared with 81% of the placebo group. Stool sample cultures revealed L. reuteri as constituting more than three-fourths of total lactobacilli.
In another study involving children hospitalized with acute diarrhea, early treatment with a combination of L. reuteri and Lactobacillus rhamnosus given twice daily for 5 days was associated with a 48% reduction in length of hospitalization in comparison with a placebo.3 At the end of the study, rotavirus was detected in 46% of children who received a placebo and 12% of those treated with lactobacilli.
In a randomized trial involving 201 infants who were given L. reuteri, Bifidobacterium lactis, or no probiotics for 12 weeks, the control group had more episodes of fever and more frequent and longer diarrhea episodes than either treatment group.4 Compared to infants who received B. lactis or no probiotics, those who received L. reuteri experienced fewer clinic visits, child care absences, days with fever, and antibiotic prescriptions.
A meta-analysis of 8 trials that evaluated the effects of L. reuteri in diarrheal diseases in children concluded that the probiotic reduces the duration of diarrhea, increases the likelihood of cure, and, in preventive settings, lowers the risk of community-acquired diarrhea in healthy children.5
In adults, L. reuteri given twice daily for 4 weeks significantly lowered the incidence of antibiotic-associated diarrhea compared to a placebo.6 While half of the placebo group developed diarrhea during the treatment period plus 2 weeks of follow-up, just 7.7% of those who received L. reuteri developed the condition.
Probiotic Bacteria L. reuteri May Improve Constipation
And in adults with chronic constipation, a randomized, double-blind trial that evaluated the effects of 4 weeks of L. reuteri supplementation resulted in an average of 2.6 more bowel movements per week among those who received the probiotic compared to 1 additional bowel movement in the placebo group.7 Another investigation of L. reuteri in constipated adults revealed a decrease in the production of methane, which can slow intestinal transit, explaining the increased bowel movement frequency seen in previous studies.8
Beneficial Effects of L. reuteri on Harmful Microorganisms
Helicobacter pylori is a bacterium largely responsible for stomach ulcers and gastric cancer. In a randomized, double-blind trial involving 100 patients who were positive for H. pylori infection, L. reuteri administered alone inhibited H. pylori growth and, when administered with H. pylori eradication therapy, lowered antibiotic-associated side effects.9
When tested against Streptococcus mutans, one of the main dental caries–causing bacteria, yogurt that contained L. reuteri significantly inhibited growth, while yogurt that contained other lactobacilli failed to have an effect.10 In a double-blind trial, the yogurt made with L. reuteri significantly reduced oral Streptococcus mutans compared to a placebo. In a randomized, double-blind trial involving subjects with chronic periodontitis, Lactobacillus reuteri Prodentis orally administered for one month was associated with a significant reduction in plaque index, bleeding on probing, and probing pocket depths, while the placebo group failed to show a statistically significant improvement.11
Frequent urinary tract infection is a challenge faced by many women worldwide. A review of the effectiveness of probiotics for this condition found L. reuteri to be among two lactobacilli that had the greatest protective effect.12
Lactobacillus reuteri could have a place in promoting workplace wellness. A double-blind trial of 262 healthy workers who received a daily dose of L. reuteri or a placebo for 80 days resulted in a significant protective effect against respiratory or gastrointestinal illnesses requiring work absences among probiotic-treated participants.13 While 26.4% of the placebo group reported taking sick leave during the study, sick leave was taken by just 10.6% of the L. reuteri group. Among 53 shift workers, 33% in the placebo group reported being sick during the study compared to none among those who received L. reuteri.
Effects on Cholesterol and Beyond
A randomized trial that compared the L. reuteri strain NCIMB 30242 to a placebo among 127 subjects with high cholesterol levels resulted in a 9.14% decrease in total cholesterol, an 11.64% reduction in low-density-lipoprotein cholesterol, and an 11.3% reduction in non-HDL cholesterol in probiotic-treated participants compared to the placebo group.14 High-sensitivity C-reactive protein (a marker of inflammation) and fibrinogen were also decreased among those who received the probiotic compared to the placebo. Interestingly, in another randomized trial, supplementation with L. reuteri NCIMB 30242 was associated with an increase in serum 25-hydroxyvitamin D levels after 9 weeks compared to a placebo.15
New findings concerning L. reuteri indicate that the lactobacillus upregulates the hormone oxytocin, associated with mood and human bonding.16
“It is now understood that gut bacteria exert effects beyond the local boundaries of the gastrointestinal tract to include distant tissues and overall health,” write S. E. Erdman and T. Poutahidis in the International Review of Neurobiology. The authors mention that Lactobacillus reuteri upregulates the hormone oxytocin and systemic immune responses, providing many health benefits. Some of these include wound healing, mental health, metabolism, and muscular and skeletal health.
Future research will reveal more concerning the mechanisms and effects of the living organisms that constitute L. reuteri, whose beneficial coexistence with humans has truly earned them the oft-heard moniker of “friendly bacteria.”
- Reuter G. Curr Issues Intest Microbiol. 2001 Sep;2(2):43-53.
- Shomikova AV et al. J Pediatr Gastroenterol Nutr. 1997 Apr;24(4):399-404.
- Rosenfeldt V et al. Pediatr Infect Dis J. 2002 May;21(5):411-6.
- Weizman Z et al. Pediatrics. 2005 Jan;115(1):5-9.
- Urbańska M et al. Aliment Pharmacol Ther. 2016 May;43(10):1025-34.
- Cimperman L et al. J Clin Gastroenterol. 2011 Oct;45(9):785-9.
- Ojetti V et al. J Gastrointestin Liver Dis. 2014 Dec;23(4):387-91.
- Ojetti V et al. Eur Rev Med Pharmacol Sci. 2017 Apr;21(7):1702-1708.
- Francavilla R. J Clin Gastroenterol. 2014 May-Jun;48(5):407-13.
- Nikawa H et al. Int J Food Microbiol. 2004 Sep 1;95(2):219-23.
- Vicario M et al. Acta Odontol Scand. 2013 May-Jul;71(3-4):813-9.
- Falagas ME et al. Drugs. 2006;66(9):1253-61.
- Tubelius P et al. Environ Health. 2005 Nov 7;4:25.
- Jones ML et al. Eur J Clin Nutr. 2012 Nov;66(11):1234-41.
- Jones ML et al. J Clin Endocrinol Metab. 2013 Jul;98(7):2944-51.
- Erdman SE et al. Int Rev Neurobiol. 2016;131:91-126.