Lactobacillus reuteri is a naturally occurring bacterial species found within the mammalian gut, with specific strains often highlighted as beneficial probiotic organisms. This bacterium is commonly isolated from the human gastrointestinal tract and is a known component of the human breast milk microbiome. Due to extensive research into its health effects, L. reuteri is recognized as one of the most thoroughly studied probiotic species available. Clinical evidence supports its use in managing a variety of digestive and non-digestive conditions across all age groups.
The Unique Biological Action of Reuteri
The therapeutic benefit of L. reuteri strains stems from unique biological mechanisms that go beyond simply adding beneficial bacteria to the gut. A primary action involves producing reuterin, a broad-spectrum antimicrobial substance. This compound is generated when the bacteria metabolize glycerol, disrupting the metabolism of numerous harmful microorganisms, including pathogenic bacteria, yeasts, and protozoa.
This inhibitory action allows L. reuteri to compete effectively against undesirables for space in the intestinal environment without harming many other beneficial organisms. Colonization is further aided by the strain’s ability to adhere to the intestinal mucosa using specialized surface proteins, such as mucus-binding protein A (CmbA). This adhesion helps establish a temporary niche where the bacteria can interact with host cells.
The strain also plays a significant role in modulating the host’s immune response, contributing to its anti-inflammatory effects. It influences signaling pathways by promoting the production of regulatory T-cells and the anti-inflammatory cytokine Interleukin-10 (IL-10). Concurrently, L. reuteri can suppress the production of pro-inflammatory mediators, such as Tumor Necrosis Factor-alpha (TNF-$\alpha$) and Interleukin-6 (IL-6). This dual action helps to calm an overactive immune response, which is a factor in many intestinal disturbances.
Targeted Clinical Applications
L. reuteri has demonstrated significant clinical efficacy in several specific health conditions, positioning it as a targeted therapeutic agent. One recognized application is the management of infant colic, where the specific strain L. reuteri DSM 17938 has been extensively studied. Clinical trials show this strain significantly reduces the daily crying and fussing time in breastfed infants with colic, often by an average of 25.4 minutes per day after three weeks of supplementation. Infants receiving the probiotic were nearly twice as likely to experience treatment success compared to those on a placebo.
The probiotic also offers a benefit for acute infectious diarrhea, particularly in children. Supplementation with L. reuteri DSM 17938 has been shown to reduce the mean duration of diarrhea by approximately 33 hours in hospitalized children and by about 15 hours in outpatients, compared to standard care alone. This reduction in symptom duration also translates to a shorter mean length of hospital stay for those requiring admission.
In older children and adults, L. reuteri is utilized to manage the gastrointestinal side effects associated with H. pylori eradication therapies. The intensive antibiotic regimen used to eliminate the bacteria often leads to uncomfortable symptoms like diarrhea and taste disturbances. Supplementation with L. reuteri ATCC 55730 reduces the frequency and intensity of these antibiotic-associated side effects, which helps improve patient adherence to the full treatment course.
Emerging research also supports the use of L. reuteri for oral health, where it acts by colonizing the oral cavity and reducing pathogenic bacteria. Targeted oral administration can lead to a measurable reduction in dental plaque formation and a decrease in gum inflammation, evidenced by a 20% reduction in bleeding on probing. Furthermore, the strain combats the anaerobic bacteria responsible for chronic halitosis, often resulting in a significant reduction in bad breath.
Practical Guidance for Using Reuteri Supplements
The effectiveness of L. reuteri is highly dependent on the specific strain used, underscoring the concept of strain specificity. For instance, strain DSM 17938 is primarily backed by research for infant colic and infectious diarrhea, while strains like L. reuteri ATCC PTA 5289 are often used for oral health. Consumers should confirm the full strain designation listed on the product label matches the strain validated for their intended use.
Dosage varies significantly based on the application. A common therapeutic dose for clinical applications, such as infant colic, is $1 \times 10^8$ Colony-Forming Units (CFUs) per day. Products designed for oral health or general gut support may contain higher concentrations, sometimes ranging into the billions of CFUs. Higher doses do not always translate to greater efficacy and may increase the likelihood of mild, transient digestive discomfort like gas or bloating.
L. reuteri supplements are available in various forms, including drops for infants, chewable tablets, and capsules. While traditional probiotics often required refrigeration, modern manufacturing techniques like freeze-drying have led to many shelf-stable L. reuteri products. Nonetheless, it is advisable to check the manufacturer’s instructions, as refrigeration may still be necessary for certain formulations or after opening to maximize potency.
L. reuteri has an excellent safety profile in healthy populations. However, individuals with severely compromised immune systems, such as those undergoing chemotherapy, should consult a healthcare provider before beginning supplementation. This ensures that the use of any live bacterial culture is medically appropriate for their specific health status.