Understanding Lactobacillus reuteri: A Strain-Specific Probiotic
While many probiotic brands simply list "Lactobacillus reuteri" on the label, the specific strain is the key to achieving targeted health benefits. L. reuteri is a species of bacteria that naturally inhabits the human gastrointestinal tract and co-evolved with humans over millions of years. However, modern diets, antibiotic use, and increased sanitation have led to a significant depletion of this beneficial species in many people. The health effects of L. reuteri are not uniform across all bacteria within the species, but are highly strain-specific. This means that a strain proven effective for infant colic may not be the one best suited for lowering cholesterol.
The Importance of Strain Identification
As of April 2020, L. reuteri was reclassified to Limosilactobacillus reuteri, though many product labels still use the older nomenclature. The specific letters and numbers after the species name (e.g., DSM 17938) are crucial because they designate a particular, well-researched variant. These designations ensure that the probiotic product delivers the specific, documented effects you are seeking. For example, a strain known for reducing inflammation in rats may not replicate that effect in humans. Therefore, savvy consumers must look beyond the species name to ensure they are getting a product with a proven track record for their intended use.
Key Functions and Mechanisms
Different L. reuteri strains provide distinct benefits through various mechanisms, including producing antimicrobial compounds like reuterin, modulating the immune system by influencing T-cell populations, and strengthening the intestinal barrier.
- Reuterin Production: Some strains produce reuterin, a potent, broad-spectrum antimicrobial agent that inhibits the growth of harmful pathogens like E. coli and Salmonella, helping to rebalance the gut microbiome. The amount of reuterin produced can vary significantly between strains.
- Immune System Modulation: Certain strains can modulate the host's immune response. For instance, L. reuteri ATCC PTA 6475 has been shown to increase regulatory T-cells in animal studies, which helps to suppress inflammation.
- Gut Barrier Function: Many strains help strengthen the intestinal barrier, preventing "leaky gut" and regulating immune responses.
Comparing Popular Lactobacillus reuteri Strains
To determine the best L. reuteri strain for your needs, consider the specific, clinically researched benefits associated with the most popular variants.
| Strain Identifier | Primary Benefit(s) | Key Clinical Evidence | Target User | Best For |
|---|---|---|---|---|
| DSM 17938 (Protectis) | Infant colic, regurgitation, constipation, diarrhea | Extensive randomized controlled trials have demonstrated significant reductions in crying time and improved bowel movements, especially in breastfed infants. | Infants and Children | Gastrointestinal issues in infants |
| NCIMB 30242 (LRC®) | Cholesterol reduction, healthy vitamin D levels | Clinical trials showed a significant reduction in LDL and total cholesterol, and an increase in circulating vitamin D levels in adults. | Adults | Cholesterol and heart health support |
| RC-14 (co-administered with GR-1) | Female urogenital health, especially bacterial vaginosis and UTIs | Studies show that oral supplementation can increase vaginal lactobacillus flora and may reduce the frequency of UTIs. | Women | Urogenital health and flora balance |
| ATCC PTA 6475 (Gastrus) | Inflammation, bone health, mood | Animal studies suggest benefits for reducing inflammation and bone loss. It is often combined with DSM 17938 in products like BioGaia Gastrus for adult gut health. | Adults | General gut health and inflammation |
| ATCC 55730 | H. pylori management, antibiotic-associated diarrhea | Shown to suppress H. pylori and reduce symptoms of antibiotic-associated diarrhea. It is the parent strain of the widely used DSM 17938. | Adults | H. pylori and diarrhea management |
How to Choose the Right Strain
When selecting a product, consider your primary health objective. Here is a guided approach:
- Identify Your Health Goal: Are you a parent of an infant with colic, an adult concerned with cholesterol, or a woman seeking urogenital support? Your goal is the most important factor.
- Match the Strain to the Need: Use the comparison table above to find the strain that has been clinically studied for your specific condition. For example, choose a product with DSM 17938 for infant colic or NCIMB 30242 for cholesterol management.
- Check for Potency and Quality: Ensure the product contains a sufficient number of Colony Forming Units (CFUs), typically in the billions, and guarantees live bacteria until the expiration date.
- Consult a Professional: Discuss your choice with a healthcare provider, especially if you are pregnant, have a weakened immune system, or have other health conditions. A professional can help ensure the probiotic is appropriate and safe for your unique situation.
The Role of Delivery and Dosage
The delivery method and dosage can also impact a probiotic's effectiveness. For infants with colic, liquid drops (like those from BioGaia) containing DSM 17938 are a standard, well-researched delivery method. For adults, capsules or chewable tablets containing the appropriate strain are common. For best results, L. reuteri should be taken consistently, as the bacteria are temporary inhabitants of the digestive tract and do not permanently colonize. Intake with food can help ensure the bacteria survive the acidic stomach environment.
Conclusion
There is no single "best" Lactobacillus reuteri strain; the most effective one is highly dependent on the targeted health outcome. For common infant issues like colic and regurgitation, DSM 17938 is the most scientifically validated choice. For adults seeking to improve cardiovascular health, the NCIMB 30242 strain has shown promising results in lowering cholesterol. For female urogenital issues, RC-14 is the strain to look for. The key to success is moving past the general species name and selecting a product with the specific, evidence-backed strain for your needs, while also considering delivery method, potency, and professional guidance.
Visit Examine.com for detailed research breakdowns on various L. reuteri strains.
Frequently Asked Questions
What is the primary difference between Lactobacillus reuteri strains?
The main difference lies in their specific, clinically-proven health benefits, which are unique to each strain. For instance, DSM 17938 is highly researched for infant colic, while NCIMB 30242 is best known for its effect on cholesterol.
Is L. reuteri DSM 17938 effective for formula-fed infants with colic?
While DSM 17938 has strong evidence for reducing crying time in breastfed infants with colic, studies in formula-fed infants have shown less consistent or no significant benefits.
How does L. reuteri NCIMB 30242 lower cholesterol?
This strain produces an enzyme called bile salt hydrolase, which makes cholesterol less absorbable and promotes its excretion from the body. It also increases the body's natural breakdown of cholesterol.
Can I take L. reuteri with other probiotics?
Yes, some strains can be taken together, and combinations are often designed for complementary effects. For example, RC-14 is often combined with L. rhamnosus GR-1 for female urogenital health.
How long does it take for L. reuteri to have an effect?
Effects can be seen within weeks, depending on the condition. For example, studies on infant colic with DSM 17938 often show results within 3 to 4 weeks. Consistency is key, as the bacteria do not permanently colonize.
Is L. reuteri safe for everyone?
L. reuteri is generally considered safe for most people, including infants, though those with weakened immune systems or damaged heart valves should consult a healthcare provider before use.
Does L. reuteri ATCC PTA 6475 help with weight loss?
Animal studies showed reduced fat mass in mice treated with ATCC PTA 6475, but this effect has not been consistently demonstrated in human trials. Strain-specific effects on weight can vary.
