What is Lactobacillus reuteri?
Lactobacillus reuteri, now technically renamed Limosilactobacillus reuteri, is a well-researched, rod-shaped probiotic bacterium that naturally inhabits the gastrointestinal tract and other body parts in humans and various animals. As a probiotic, its administration in adequate amounts is known to confer numerous health benefits to the host. Unlike some other lactic acid bacteria, L. reuteri is particularly notable for its host-adapted lineages and its ability to colonize the gut effectively. Its diverse range of effects is primarily mediated through several key mechanisms, including the production of antimicrobial compounds, modulation of the immune system, and enhancement of the gut barrier.
The Multifaceted Mechanisms of Lactobacillus reuteri
The probiotic effects of L. reuteri are not singular but result from several distinct biochemical actions within the body. These include:
- Production of antimicrobial compounds: Some strains produce reuterin, a potent, broad-spectrum antimicrobial agent that inhibits the growth of various harmful bacteria, yeasts, and fungi, helping to balance the gut microbiota.
- Immune system modulation: L. reuteri can influence the immune system by reducing pro-inflammatory cytokines and promoting regulatory T-cell development, which helps to mitigate inflammation systemically. Certain strains can also activate the aryl hydrocarbon receptor (AhR), which is linked to reduced intestinal and systemic inflammation.
- Strengthening the gut barrier: This probiotic enhances the integrity of the intestinal lining by improving the function of tight junctions, which prevents microbial translocation from the gut into the bloodstream and reduces overall inflammation.
- Metabolite production: It can produce various beneficial metabolites, including short-chain fatty acids (SCFAs), and some strains can even synthesize vitamins such as B12 and folate.
Key Health Effects Across the Lifespan
Infant and Child Health:
- Infantile Colic: L. reuteri DSM 17938 is one of the most studied and effective strains for reducing crying time in breastfed infants with colic. This effect is believed to be linked to its ability to remodel the infant gut microbiota and reduce intestinal inflammation.
- Diarrhea: Supplementation has been shown to reduce the duration and severity of acute infectious diarrhea in young children, including rotavirus-associated cases.
- Functional Abdominal Pain: Studies suggest that it can help reduce symptoms associated with functional abdominal pain syndrome in children.
Adult Digestive Health:
- Constipation: Certain strains, like DSM 17938, have shown potential in alleviating chronic constipation, particularly in cases linked to methane-dominant small intestinal bacterial overgrowth (SIBO). It can improve gut motility and increase bowel movement frequency.
- Helicobacter pylori Infection: When used alongside standard antibiotic therapy, L. reuteri has demonstrated the ability to reduce H. pylori load, improve eradication rates, and lessen the gastrointestinal side effects associated with the antibiotic treatment.
- IBS and General Gut Discomfort: It helps reduce a range of digestive symptoms like abdominal pain, bloating, and diarrhea or constipation by balancing gut flora and reducing inflammation.
Impact on Extraintestinal Health
L. reuteri's influence extends beyond the digestive system, affecting other aspects of the body's health.
- Oral Health: In the oral cavity, it competes with pathogenic bacteria that cause dental plaque, gingivitis, and periodontitis. It also helps reduce oral pathogens and inflammatory markers. Some studies have found it can help combat halitosis.
- Skin Health: The gut-skin axis suggests a link between gut microbiota and skin conditions. Some research indicates that L. reuteri may improve skin barrier function, reduce inflammatory skin conditions like acne and eczema, and offer antioxidant benefits. Animal studies have shown potential benefits for reducing UV-induced skin damage and photoaging.
- Bone Health: A specific strain, ATCC PTA 6475, has been studied for its potential role in preventing age-related bone loss and osteoporosis in older women.
Comparing Specific L. reuteri Strains
Probiotic effects are often strain-specific, and the benefits of L. reuteri are no exception. The following table compares some well-studied strains:
| Feature | L. reuteri DSM 17938 | L. reuteri ATCC PTA 6475 | L. reuteri ATCC 55730 |
|---|---|---|---|
| Associated Conditions | Infantile colic, diarrhea, methane-dominant SIBO, H. pylori support | Bone health (osteoporosis), some oral health effects | Infantile colic, diarrhea |
| Mechanism | Produces reuterin, modulates gut microbiota, anti-inflammatory | Produces histamine which suppresses inflammatory responses | Immune modulation, produces reuterin |
| Safety Note | Developed by removing antibiotic resistance plasmids from ATCC 55730 for increased safety | Generally regarded as safe (GRAS), well-studied | Contains potentially transferable antibiotic resistance genes; replaced by DSM 17938 for commercial use |
Dosage and Considerations
Dosage for L. reuteri varies depending on the specific strain, the condition being treated, and the individual. Clinical doses often range from 100 million to 50 billion colony-forming units (CFUs) daily. It is important to note that colonization will not persist indefinitely after supplementation is stopped. Mild, temporary side effects like bloating, gas, or diarrhea can occur as the body adjusts, but these usually resolve quickly. Individuals with compromised immune systems, such as those undergoing chemotherapy, should consult a healthcare provider before taking probiotics due to a very low risk of infection. Pregnant or breastfeeding women should also seek medical advice. For optimal results, pairing supplementation with a diet rich in prebiotic fiber can support the growth of beneficial bacteria.
Conclusion
The effect of Lactobacillus reuteri is both well-documented and far-reaching, encompassing significant benefits for gastrointestinal, immune, oral, and potentially bone and skin health. Its mechanisms, including the production of antimicrobial compounds and immune modulation, allow it to address a wide range of issues from infant colic to chronic constipation and inflammation. As different strains exhibit different properties, selecting the appropriate one for a specific health goal is crucial. While generally safe, seeking professional advice is recommended, especially for sensitive populations. Continued research promises to further clarify the full extent of its therapeutic potential. For more information on the specific properties and research surrounding this probiotic, consult reliable sources like the National Institutes of Health (NIH).
