Lactobacillus Rhamnosus

• Gut microbiome balance
• Immune system modulation
• Intestinal barrier protection
• Pathogen inhibition

• Antibiotic-associated diarrhea prevention
• Respiratory infection reduction
• Atopic dermatitis prevention in children
• Irritable bowel syndrome symptom relief
• Traveler’s diarrhea prevention
• Vaginal health support
• Oral health maintenance

Lactobacillus rhamnosus exerts its beneficial effects through multiple mechanisms that contribute to gut health, immune modulation, and protection against pathogens. As a probiotic, L. rhamnosus competes with pathogenic microorganisms for adhesion sites on intestinal epithelial cells, effectively preventing colonization by harmful bacteria. This competitive exclusion is particularly effective due to L.

rhamnosus’s strong adhesion properties, especially in the L. rhamnosus GG (LGG) strain, which possesses specific pili (hair-like structures) that enhance attachment to intestinal mucosa. L. rhamnosus produces lactic acid and other organic acids that lower the intestinal pH, creating an environment unfavorable for many pathogenic bacteria.

It also produces antimicrobial compounds, including bacteriocins and hydrogen peroxide, which directly inhibit the growth of harmful microorganisms. One of the key mechanisms of L. rhamnosus is its ability to strengthen the intestinal barrier function by enhancing tight junction proteins (such as occludin and claudins) between epithelial cells, thereby reducing intestinal permeability and preventing the translocation of pathogens and toxins across the intestinal wall. L.

rhamnosus also stimulates mucin production by goblet cells, creating a protective layer over the intestinal epithelium. In terms of immune modulation, L. rhamnosus interacts with gut-associated lymphoid tissue (GALT) and influences both innate and adaptive immunity. It enhances the activity of natural killer cells, macrophages, and dendritic cells, which are crucial components of the innate immune system.

L. rhamnosus also promotes the production of secretory IgA antibodies, which provide mucosal protection against pathogens. A particularly important aspect of L. rhamnosus’s immune modulation is its ability to induce regulatory T cells (Tregs) and balance the Th1/Th2 immune response, which helps prevent excessive inflammation and may contribute to its beneficial effects in allergic conditions.

L. rhamnosus GG has been shown to produce specific proteins that activate the STAT1 and NF-κB signaling pathways, influencing cytokine production and immune cell function. L. rhamnosus also modulates the gut-brain axis through the production of neurotransmitters and neuroactive compounds, potentially affecting mood, stress response, and cognitive function.

This may explain some of its observed effects on anxiety and depression in certain studies. In the context of antibiotic-associated diarrhea, L. rhamnosus helps restore the gut microbiota balance disrupted by antibiotics, preventing opportunistic pathogens like Clostridioides difficile from proliferating. For atopic conditions, L.

rhamnosus appears to modulate the immune system toward a more balanced Th1/Th2 response and promotes tolerance through regulatory T cells and dendritic cells. In the vaginal environment, L. rhamnosus helps maintain a healthy acidic pH through lactic acid production and competes with urogenital pathogens for adhesion sites, reducing the risk of bacterial vaginosis and urinary tract infections. L.

rhamnosus also produces enzymes that aid in the breakdown of certain food components and may help alleviate lactose intolerance in some individuals. Recent research has also identified strain-specific mechanisms, particularly for LGG, including the production of specific proteins (p40 and p75) that promote intestinal epithelial cell survival and growth through activation of the epidermal growth factor receptor (EGFR).

The optimal dosage of Lactobacillus rhamnosus varies depending on the specific condition being addressed, the strain used (particularly whether

it ‘s the well-studied LGG strain), and individual factors. Generally, dosages range from 1 billion to 20 billion colony-forming units (CFU) per day for general health maintenance,

while therapeutic dosages for specific conditions may range from 10 billion to 40 billion CFU daily.

It ‘s important to note that efficacy is not solely determined by CFU count but also by strain specificity, viability at the site of action, and the particular health condition being addressed.

Lactobacillus rhamnosus is not ‘absorbed’ in the traditional sense of dietary supplements. Instead, its bioavailability refers to the percentage of live bacteria that survive the harsh conditions of the gastrointestinal tract to reach their site of action. L. rhamnosus, particularly the GG strain (LGG), has relatively good survival rates compared to many other probiotic strains.

Studies suggest that approximately 15-30% of orally administered L. rhamnosus may survive passage through the stomach and upper intestine, though this varies widely depending on formulation, strain characteristics, and individual factors such as gastric acidity and transit time. L. rhamnosus GG has demonstrated superior acid and bile resistance compared to many other probiotic strains, which contributes to its efficacy.

Once it reaches the intestines, L. rhamnosus can temporarily colonize the gut mucosa, with detectable levels persisting for 1-2 weeks after discontinuation in many individuals.

Enteric coating: Protects probiotics from stomach acid, increasing survival rates by 30-60%, Microencapsulation: Shields bacteria from environmental stressors, potentially improving viability by 40-70%, Delayed-release capsules: Designed to release probiotics in the intestines rather than the stomach, Buffered formulations: Include compounds that neutralize stomach acid around the bacteria, Prebiotic inclusion (synbiotics): Provides nutrients that support probiotic growth and colonization, particularly fructooligosaccharides (FOS) and inulin, Higher CFU counts: Compensates for die-off during transit, though quality and strain characteristics are more important than quantity alone, Refrigerated storage: Maintains viability before consumption, Consumption with meals: Food can buffer stomach acid and improve survival, Acid-resistant strains: L. rhamnosus GG is naturally more acid-resistant than many other probiotic strains, Freeze-dried preparations: Maintain stability until hydration in the digestive tract

For maximum effectiveness, L. rhamnosus supplements are best taken with or just before meals, which helps buffer stomach acid and improve survival rates. When taken for antibiotic-associated diarrhea prevention, L. rhamnosus should be administered at least 2 hours before or after antibiotics to prevent direct antimicrobial effects on the probiotic.

For general digestive health, consistent daily supplementation is more important than specific timing. Morning administration may be preferable for some individuals as gastric emptying tends to be faster in the morning, potentially allowing more bacteria to reach the intestines. For prevention of respiratory infections or atopic conditions, timing is less critical than consistent daily use. For travelers taking L.

rhamnosus to prevent traveler’s diarrhea, it’s recommended to begin supplementation 2-3 days before travel and continue throughout the trip and for 2-3 days after return. When used as an adjunct to H. pylori treatment, L. rhamnosus should be taken at a different time than the antibiotic regimen, ideally with food.

For maximum colonization potential, consistent daily use at approximately the same time each day is recommended, as L. rhamnosus typically remains in the gut for only 1-2 weeks after discontinuation.

• Temporary digestive discomfort (gas, bloating)
• Mild abdominal cramping
• Increased thirst (rare)
• Headache (rare)
• Constipation (rare)
• Increased appetite (rare)
• Taste disturbances (rare)
• Skin rash (very rare)

• Severely immunocompromised patients (e.g., those with AIDS, lymphoma, or undergoing long-term corticosteroid treatment)
• Patients with short bowel syndrome
• Individuals with central venous catheters
• Critically ill patients in intensive care units
• Premature infants (especially very low birth weight infants)
• Patients with damaged heart valves or artificial heart valves
• Known hypersensitivity to Lactobacillus species or any components of the probiotic formulation

• Antibiotics (may reduce probiotic effectiveness; separate administration by at least 2 hours)
• Immunosuppressants (theoretical increased risk of infection)
• Antifungal medications (may reduce probiotic effectiveness)
• Medications that decrease stomach acid (may increase probiotic survival but potentially affect colonization patterns)
• Anticoagulants/antiplatelet drugs (rare case reports of increased bleeding risk with certain probiotics, though not specifically with L. rhamnosus)

No established upper limit for L. rhamnosus. Doses up to 40 billion CFU daily have been used in clinical studies without significant adverse effects in healthy individuals. However, higher doses may increase the risk of side effects such as digestive discomfort without necessarily providing additional benefits.

The appropriate dose depends on the specific condition being treated and individual factors. For general health maintenance, 1-10 billion CFU daily is typically sufficient. Individuals with compromised immune systems should consult healthcare providers before using any dose of probiotics. It’s important to note that safety concerns are more related to an individual’s health status than to specific dosage thresholds.

Lactobacillus rhamnosus, particularly the GG strain (LGG), has an excellent safety profile and is one of the most extensively studied probiotics. It has Generally Recognized as Safe (GRAS) status in the United States and Qualified Presumption of Safety (QPS) status in the European Union. However, there have been rare cases of Lactobacillus bacteremia (bacteria in the blood) in severely immunocompromised individuals or those with serious underlying health conditions. While L.

rhamnosus has a long history of safe use in foods and supplements, caution is advised in certain populations. Individuals with severe acute pancreatitis should avoid probiotics, as some studies have suggested potential harm in this specific condition. Those with a history of endocarditis or artificial heart valves should consult healthcare providers before use. Diabetic patients should check probiotic supplement labels for added sugars.

Individuals with milk allergies should ensure that dairy-free formulations are selected, as some L. rhamnosus products are cultured in dairy-based media. Patients scheduled for surgery should inform their healthcare providers about probiotic use, as some practitioners recommend discontinuation 1-2 weeks before major surgical procedures. While L.

rhamnosus GG has been extensively studied in pregnancy and early childhood with a good safety profile, pregnant women should still consult healthcare providers before starting any supplement regimen.

In the United States, Lactobacillus rhamnosus has Generally Recognized as Safe (GRAS) status when used in traditional food applications. The GG strain (LGG) specifically has received GRAS status for use in infant formula and various food products. As a dietary supplement ingredient, L. rhamnosus is regulated under the Dietary Supplement Health and Education Act (DSHEA) of 1994.

Under this framework, manufacturers are responsible for ensuring the safety of their products before marketing, but pre-market approval is not required. The FDA does not approve dietary supplements for safety or efficacy. Manufacturers of L. rhamnosus supplements may make structure/function claims (e.g., ‘supports digestive health’) but cannot make disease claims (e.g., ‘treats antibiotic-associated diarrhea’) without going through the drug approval process.

In September 2023, the FDA issued a warning regarding the use of probiotics in hospitalized preterm infants, citing safety concerns, though this was not specific to L. rhamnosus alone. For food applications, L. rhamnosus is permitted as an ingredient in yogurt and other fermented dairy products according to the standards of identity established by the FDA.

Eu: In the European Union, L. rhamnosus has Qualified Presumption of Safety (QPS) status, the European equivalent of GRAS. For use in foods, L. rhamnosus must be included on the Union list of authorized food additives. For probiotic health claims, the European Food Safety Authority (EFSA) has established strict criteria. To date, EFSA has not approved any specific health claims for L. rhamnosus, though it is permitted as a food ingredient. In food supplements (the EU term for dietary supplements), L. rhamnosus is regulated under the Food Supplements Directive (2002/46/EC). Some member states have established national lists of permitted probiotic strains for use in food supplements. L. rhamnosus GG is widely used in dairy products and supplements throughout the EU.

Canada: Health Canada has included L. rhamnosus on its Natural Health Products Ingredients Database with approved use as a source of probiotics. It is permitted in Natural Health Products (NHPs) with specific approved claims related to gut health and immune function. L. rhamnosus GG has been approved for several specific health claims, including helping to reduce the risk of antibiotic-associated diarrhea. L. rhamnosus is also permitted as a food ingredient in products like yogurt. For probiotic products making health claims, pre-market approval is required through the Natural and Non-prescription Health Products Directorate (NNHPD).

Australia: In Australia, L. rhamnosus is regulated by the Therapeutic Goods Administration (TGA) when used in complementary medicines (similar to dietary supplements). It is listed in the Therapeutic Goods (Permissible Ingredients) Determination and can be used in listed medicines. For food applications, Food Standards Australia New Zealand (FSANZ) permits L. rhamnosus as a food ingredient. Health claims are regulated under the Australia New Zealand Food Standards Code, with strict requirements for substantiation.

Japan: In Japan, L. rhamnosus can be used in Foods for Specified Health Uses (FOSHU) if approved by the Consumer Affairs Agency. It is also permitted in regular foods and as an ingredient in ‘Foods with Function Claims’ (FFC) if scientific evidence supports the claimed benefits. Japan has a long history of accepting probiotic foods, with fermented milk products containing L. rhamnosus widely available.

China: In China, L. rhamnosus is included in the list of approved probiotic strains for use in foods by the National Health Commission. For use in health foods (similar to dietary supplements), approval from the State Administration for Market Regulation (SAMR) is required. The regulatory framework for probiotics in China has been evolving, with increasing scrutiny of health claims.

India: The Food Safety and Standards Authority of India (FSSAI) permits L. rhamnosus in certain food categories, including dairy products. For use in nutraceuticals or health supplements, it must comply with the Food Safety and Standards (Health Supplements, Nutraceuticals, Food for Special Dietary Use, Food for Special Medical Purpose, Functional Food and Novel Food) Regulations.

The regulatory landscape for L. rhamnosus and other probiotics faces several challenges. There is significant international variation in how probiotics are regulated, creating complexity for global marketing. Strain-specific effects are not always reflected in regulatory frameworks, which may treat all L.

rhamnosus strains as equivalent despite evidence of strain-specific benefits (particularly for the GG strain). Dosage standardization is lacking, with no consensus on minimum effective doses for different health applications. Quality control standards vary widely, with inconsistent requirements for viability testing, contamination screening, and stability assessment. Health claim substantiation requirements differ significantly between jurisdictions, with some regions (like the EU) having very stringent requirements that few probiotic products can meet.

The line between food and supplement/drug classifications is often blurry for probiotic products, creating regulatory uncertainty. Emerging delivery formats (e.g., probiotic-infused beauty products, lozenges, or topical applications) may fall into regulatory gray areas. Safety monitoring systems for probiotics are less developed than for conventional drugs, though adverse events appear to be rare in healthy populations. As research advances on the microbiome and probiotic mechanisms, regulatory frameworks may need to evolve to accommodate new understanding and applications.

The recent taxonomic reclassification of L. rhamnosus to Lacticaseibacillus rhamnosus may create additional regulatory complexities during the transition period as labels and regulatory documents are updated.

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The cost of Lactobacillus rhamnosus supplements varies widely based on formulation, strain specificity (particularly whether it contains the well-researched GG strain), CFU count, and additional ingredients. Basic L. rhamnosus supplements typically range from $0.10 to $0.50 per billion CFU. For a typical effective dose of 1-10 billion CFU daily for general health maintenance, this translates to approximately $0.10-$5.00 per day.

Higher potency supplements (10-20 billion CFU) generally cost $0.30-$1.50 per day. Premium formulations with verified L. rhamnosus GG strain, advanced delivery systems, or additional ingredients can cost $1.00-$3.00 per day. Specialized therapeutic formulations for specific conditions may cost up to $3.00-$5.00 per day.

Food sources of L. rhamnosus, such as certain yogurts with live cultures, typically cost $0.50-$2.00 per serving, though CFU counts are often lower and less standardized than in supplements.

The cost-effectiveness of L. rhamnosus supplementation varies by application and individual needs. For preventing antibiotic-associated diarrhea, L. rhamnosus GG supplementation is generally highly cost-effective, as the cost of supplementation ($10-$30 for a typical antibiotic course) is substantially lower than potential costs associated with treating diarrhea, including medication, lost productivity, and in severe cases, hospitalization.

Studies suggest that L. rhamnosus GG can reduce the risk of antibiotic-associated diarrhea by approximately 50%, representing significant value. For acute infectious diarrhea treatment, particularly in children, L. rhamnosus GG offers good value by potentially reducing the duration of illness by about 24 hours, which can translate to reduced healthcare costs and faster return to normal activities.

For atopic dermatitis prevention in high-risk infants, the value proposition is moderate to high when considering the potential long-term costs of managing atopic conditions. The initial investment in prenatal and infant supplementation ($150-$300 for the recommended period) may be offset by reduced medical costs if the intervention successfully prevents or delays atopic manifestations. For general digestive health maintenance in healthy individuals, the value is less clearly established. Lower-cost options ($10-$30 per month) may be reasonable for preventive health, while premium products may not offer proportionally greater benefits for general wellness.

For respiratory infection prevention, the value varies seasonally, with potentially better cost-effectiveness during winter months or high-risk periods. Food sources of L. rhamnosus (certain yogurts, kefir) often provide good value for general health maintenance, combining nutritional benefits with probiotic delivery, though at less standardized doses. Generic or store-brand probiotic supplements can offer good value, but verification of strain identity is important, particularly when seeking the well-researched GG strain.

Multi-strain formulations typically cost more but may provide broader benefits than single-strain L. rhamnosus products. The most cost-effective approach often involves targeted, time-limited use for specific conditions rather than indefinite daily supplementation without a clear indication.

The shelf life of Lactobacillus rhamnosus products varies significantly based on formulation, packaging, and storage conditions. Properly manufactured and stored freeze-dried L. rhamnosus supplements typically maintain acceptable viability for 18-24 months from the date of manufacture. L.

rhamnosus GG (LGG) has demonstrated relatively good stability compared to many other probiotic strains, with some properly formulated products maintaining viability for up to 24-36 months at room temperature. Refrigerated liquid formulations generally have a shorter shelf life of 2-3 months. Microencapsulated or specially formulated shelf-stable products may maintain viability for up to 24-36 months at room temperature. Probiotic-fortified foods like yogurt typically have shelf lives of 3-6 weeks under refrigeration, with probiotic counts gradually declining over this period.

Refrigeration (36-46°F/2-8°C) is optimal for most L. rhamnosus supplements, even those labeled as shelf-stable, as it significantly extends viability. If refrigeration is not possible, store in a cool, dry place away from direct sunlight, heat sources, and humidity. Temperature fluctuations should be minimized, as repeated warming and cooling can reduce viability.

Keep containers tightly closed when not in use to prevent moisture exposure. For blister-packed probiotics, only remove capsules/tablets when ready to consume. Liquid formulations almost always require refrigeration after opening. Follow manufacturer-specific storage instructions, as some advanced formulations may have different requirements.

When traveling, consider using insulated containers with ice packs for temperature-sensitive formulations, or look for specially designed shelf-stable travel formulations. L. rhamnosus GG has demonstrated relatively good stability at room temperature compared to many other probiotic strains, but refrigeration will still extend its shelf life.

Heat: Temperatures above 77°F/25°C accelerate die-off of live bacteria; exposure to temperatures above 104°F/40°C can cause rapid loss of viability., Moisture: Exposure to humidity or moisture activates freeze-dried bacteria prematurely, depleting their energy reserves and reducing shelf life., Oxygen: L. rhamnosus is microaerophilic (prefers low oxygen), and excessive oxygen exposure can reduce viability through oxidative damage., Light: Direct sunlight and UV light can damage bacterial cells through photodegradation and generation of reactive oxygen species., pH extremes: While L. rhamnosus is relatively acid-tolerant (particularly the GG strain), extreme pH conditions during storage can reduce viability., Freeze-thaw cycles: Repeated freezing and thawing creates ice crystals that can damage bacterial cell walls., Chemical preservatives: Many preservatives used in foods and supplements are designed to inhibit microbial growth and may affect probiotic viability., Compression and processing: Mechanical stress during manufacturing and compression into tablets can damage bacterial cells., Interaction with other ingredients: Certain active ingredients in multi-component supplements may have antimicrobial properties that reduce probiotic viability over time.

Several technologies have been developed to enhance the stability of L. rhamnosus products. Microencapsulation protects bacteria with a protective coating that shields them from environmental stressors and controls their release. Freeze-drying (lyophilization) removes water while preserving the cellular structure, significantly extending shelf life.

Addition of cryoprotectants like trehalose, sucrose, or glycerol helps protect bacterial cells during freeze-drying and storage. Specialized packaging such as nitrogen-flushed bottles, blister packs, or aluminum foil sachets reduces exposure to oxygen and moisture. Some formulations include prebiotics that not only support growth in the gut but may also enhance stability during storage. Advanced formulations may incorporate acid-resistant strains (L.

rhamnosus GG is naturally relatively acid-resistant) or add buffering agents to protect against pH fluctuations. Vacuum-sealed packaging removes oxygen that could damage sensitive probiotic strains. Cold-chain management throughout manufacturing, distribution, and retail ensures optimal temperature conditions are maintained. Some manufacturers use overages (adding more CFUs than stated on the label) to compensate for expected die-off during shelf life, ensuring that the product contains at least the labeled amount of viable probiotics through the expiration date.

Synthesis Methods

Natural Sources

Quality Considerations

Lactobacillus rhamnosus has a more recent history of documented use compared to some other probiotic species, with its specific identification and application primarily occurring in the modern scientific era. While fermented foods containing various lactic acid bacteria have been consumed for thousands of years across diverse cultures, the specific isolation and characterization of L. rhamnosus is a relatively recent development. The species was first isolated and described in the early 20th century from intestinal sources, though it was initially classified under different taxonomic designations before being recognized as a distinct species.

The name ‘rhamnosus’ refers to the bacterium’s ability to ferment the sugar rhamnose. The most significant milestone in the history of L. rhamnosus came in 1985 when the GG strain (LGG) was isolated from the intestinal tract of a healthy human by Drs. Sherwood Gorbach and Barry Goldin at Tufts University in Boston, Massachusetts.

The strain was named using the initials of its discoverers (Gorbach and Goldin). LGG was selected from among hundreds of lactic acid bacterial strains for its exceptional properties, including strong adherence to intestinal epithelial cells, acid and bile resistance, antimicrobial activity against pathogens, and safety for human consumption. In 1987, Valio Ltd., a Finnish dairy company, acquired the rights to LGG and began incorporating it into dairy products. This marked one of the first commercial applications of a specifically selected probiotic strain based on scientific criteria rather than traditional fermentation practices.

The 1990s saw the beginning of extensive scientific research on L. rhamnosus GG, with early clinical studies focusing on its potential to prevent and treat diarrheal diseases, particularly in children. A landmark study published in 1990 by Isolauri and colleagues demonstrated the efficacy of LGG in reducing the duration of acute diarrhea in children, which helped establish its reputation as a therapeutic probiotic. Throughout the 1990s and 2000s, research on L.

rhamnosus GG expanded to include studies on antibiotic-associated diarrhea, atopic diseases, respiratory infections, and other conditions. The strain became one of the most extensively studied probiotics worldwide, with hundreds of published clinical trials and research papers. In parallel with the growing scientific evidence, commercial applications of L. rhamnosus expanded beyond dairy products to include dietary supplements, infant formulas, and other functional foods.

The strain has been incorporated into numerous commercial products globally and is one of the few probiotics with substantial clinical evidence supporting specific health benefits. In 2020, taxonomic revisions led to the reclassification of many Lactobacillus species into new genera, with L. rhamnosus being reclassified as Lacticaseibacillus rhamnosus. However, the name Lactobacillus rhamnosus remains in common use in both scientific and commercial contexts.

Today, L. rhamnosus GG is one of the most widely used and researched probiotic strains globally, with applications ranging from general digestive health to specific clinical conditions. Its history represents a bridge between traditional fermented foods and modern, evidence-based probiotic therapy, exemplifying the evolution of probiotics from traditional foods to scientifically validated health products.

Szajewska H, Kołodziej M. Systematic review with meta-analysis: Lactobacillus rhamnosus GG in the prevention of antibiotic-associated diarrhoea in children and adults. Aliment Pharmacol Ther. 2015;42(10):1149-1157., Goldenberg JZ, et al. Probiotics for the prevention of Clostridium difficile-associated diarrhea in adults and children. Cochrane Database Syst Rev. 2017;12:CD006095., Hao Q, et al. Probiotics for preventing acute upper respiratory tract infections. Cochrane Database Syst Rev. 2015;2:CD006895., Cuello-Garcia CA, et al. Probiotics for the prevention of allergy: A systematic review and meta-analysis of randomized controlled trials. J Allergy Clin Immunol. 2015;136(4):952-961., Urbańska M, Szajewska H. The efficacy of Lactobacillus reuteri DSM 17938 in infants and children: a review of the current evidence. Eur J Pediatr. 2014;173(10):1327-1337., Ford AC, et al. Efficacy of prebiotics, probiotics, and synbiotics in irritable bowel syndrome and chronic idiopathic constipation: Systematic review and meta-analysis. Am J Gastroenterol. 2014;109(10):1547-1561.

Lactobacillus rhamnosus GG for Prevention of Necrotizing Enterocolitis in Very Low Birth Weight Infants (ClinicalTrials.gov Identifier: NCT03755934), Efficacy of Lactobacillus rhamnosus GG in Children with Autism Spectrum Disorder (ClinicalTrials.gov Identifier: NCT03316625), Lactobacillus rhamnosus GG for Prevention of Antibiotic-Associated Diarrhea in Hospitalized Elderly Patients (ClinicalTrials.gov Identifier: NCT04091451), Effects of Lactobacillus rhamnosus GG on Cognitive Function in Older Adults (ClinicalTrials.gov Identifier: NCT04153214), Lactobacillus rhamnosus GG as an Adjunct to Standard Therapy for Helicobacter pylori Eradication (ClinicalTrials.gov Identifier: NCT03902561)

Lactobacillus rhamnosus, particularly the GG strain (LGG), is one of the most extensively studied probiotics with a substantial body of scientific evidence supporting several of its health benefits. The strongest evidence supports the use of L. rhamnosus GG for preventing antibiotic-associated diarrhea, with multiple meta-analyses showing approximately 50% risk reduction in both children and adults. There is also good evidence for its effectiveness in treating acute infectious diarrhea, particularly in children, with studies showing reduction in duration of diarrhea by approximately 24 hours.

Moderate evidence supports the use of L. rhamnosus GG for preventing atopic dermatitis when administered to pregnant women in the last trimester and to infants in the first year of life, particularly in those with a family history of atopy. The evidence for L. rhamnosus in preventing respiratory infections is promising but less consistent, with some studies showing reduced incidence and severity of respiratory infections, particularly in children.

For irritable bowel syndrome (IBS), the evidence is mixed, with some studies showing modest benefits for symptom relief, particularly when combined with other probiotic strains. The evidence for L. rhamnosus as an adjunct therapy for Helicobacter pylori infection is emerging, with studies suggesting improved eradication rates and reduced side effects when added to standard treatment. Recent research has also explored the potential benefits of L.

rhamnosus for immune modulation in specific populations, such as HIV-infected individuals, with promising preliminary results. However, not all studies have shown positive results. A large, well-designed trial published in the New England Journal of Medicine in 2018 found that L. rhamnosus GG was not effective in preventing moderate-to-severe gastroenteritis in children, highlighting the importance of context, specific conditions, and population characteristics in determining efficacy.

The quality of evidence varies across different applications, with the strongest evidence coming from multiple well-designed randomized controlled trials and meta-analyses for antibiotic-associated diarrhea prevention. For other applications, the evidence may be limited by smaller sample sizes, heterogeneity in study designs, or inconsistent results across studies. It’s important to note that the effects of L. rhamnosus are strain-specific, with the GG strain having the most extensive research support.

Other strains may have different effects and levels of evidence.