Lactobacillus reuteri DSM 17938 is a specific and extensively studied probiotic strain that has garnered significant attention. This microbe is a commercially available supplement, often highlighted for its use in supporting gastrointestinal health, especially in early life. The strain’s popularity in infant and pediatric health is due to research investigating its potential to alleviate various common digestive discomforts. Understanding the science behind this designation, its biological actions, and its proven applications is important for appreciating its role as a therapeutic probiotic.
Defining the Specific Strain
The designation “DSM 17938” represents a unique bacterial isolate with a defined genetic and functional profile. The three-part name (genus, species, and strain) is necessary because probiotic effects are highly strain-specific; findings for one Lactobacillus reuteri strain do not apply to others. This strain is a derivative of Lactobacillus reuteri ATCC 55730, which was originally isolated from the breast milk of a Peruvian mother.
The strain DSM 17938 was developed from the parent strain by removing a plasmid that carried antibiotic resistance genes, ensuring a safer commercial profile. It is a human-derived organism naturally found in the human gastrointestinal tract. Although the species was officially reclassified to Limosilactobacillus reuteri in 2020, the original nomenclature of L. reuteri DSM 17938 remains widely used in research and commercial products.
Strain specificity is a fundamental concept in probiotic science, explaining why clinical results are often not interchangeable between different bacterial cultures. The unique characteristics of DSM 17938, such as its ability to temporarily colonize the gut and its specific metabolic output, differentiate its efficacy from other strains. By adhering to the precise DSM 17938 designation, researchers and consumers can ensure that the results of clinical trials are relevant to the product being used.
Biological Mechanisms of Action
The beneficial actions of L. reuteri DSM 17938 stem from direct antimicrobial effects, competitive interactions within the gut, and modulation of host processes. A notable action is the production of reuterin, a broad-spectrum antimicrobial substance. Reuterin is created through the anaerobic metabolism of glycerol and inhibits the growth of various pathogenic bacteria, yeasts, and protozoa, helping to balance the gut microbiome.
The strain employs competitive exclusion, physically outcompeting undesirable microbes for resources and colonization sites on the intestinal lining. It adheres to mucin, the protective layer coating the intestinal epithelium, using specific surface proteins. By occupying these sites, DSM 17938 prevents harmful bacteria from establishing a foothold.
The strain also interacts with the host’s intestinal barrier and immune system. It strengthens the gut lining, potentially reducing intestinal permeability and improving overall barrier integrity. The strain demonstrates immunoregulatory properties by helping to down-regulate pro-inflammatory cytokines, which are signaling molecules involved in inflammation. This anti-inflammatory action contributes to its therapeutic effect in certain gastrointestinal disorders.
Proven Health Applications
Clinical evidence supports the use of L. reuteri DSM 17938 in pediatric functional gastrointestinal disorders. A primary use is the reduction of crying time in infants with colic, characterized by excessive, unexplained crying. Studies show that daily administration can significantly reduce the duration of crying in breastfed infants, leading to a quicker resolution of symptoms.
The strain also manages functional constipation, which involves infrequent or difficult bowel movements. In infants and children, supplementation has been shown to increase the frequency of bowel movements and improve stool consistency. This effect on gut motility is related to its influence on the gut environment, helping to normalize intestinal function.
Another application is the management of acute infectious diarrhea, particularly in children. Supplementation shortens the duration of diarrhea episodes and reduces the frequency of watery stools. This is due to the strain’s antimicrobial action from reuterin and its ability to enhance gut barrier function, aiding recovery from infection.
Additionally, daily use in premature infants has been associated with a reduction in the risk of developing necrotizing enterocolitis (NEC), a severe gastrointestinal disease. The overall body of evidence across multiple gastrointestinal conditions establishes its place as a well-researched probiotic in pediatrics. Continued research is helping to clarify the precise patient populations who benefit most from its use.
Safety Profile and Usage Guidelines
Lactobacillus reuteri DSM 17938 has a well-established safety record, even in vulnerable populations like preterm infants. It is considered safe and well-tolerated, with minimal reported side effects, typically mild and transient gastrointestinal symptoms such as gas or bloating. Studies in adults and children have found no severe adverse events linked to its consumption, even when administered at high doses.
The common dosage for therapeutic applications, particularly in infants, is $10^8$ Colony Forming Units (CFU), or 100 million organisms, administered once daily. This dose is often provided in an oil-based suspension, such as drops, for easy administration directly into the mouth, or mixed with formula or breast milk. For adults, dosages can vary, but the strain has been found to be safe at doses up to $10^{11}$ CFU per day.
Product stability is a practical consideration for probiotics, and DSM 17938 is often formulated to maintain viability without requiring refrigeration. Many commercial products containing the strain are sold as drops or chewable tablets, and the formulation is designed to ensure that the stated number of live organisms remains active throughout the product’s shelf life.