Lactobacillus Reuteri: Benefits, Dosage & How to Choose the Right Supplement
Lactobacillus reuteri is one of the few probiotic strains that naturally colonizes the human gut from infancy. It has been the subject of over 200 clinical trials, making it one of the most studied probiotics worldwide. If you're considering a probiotic supplement, understanding what L. reuteri can and cannot do is worth your time.
Who this is for: Anyone considering probiotic supplementation for gut health, immune support, or specific conditions like colic, H. pylori, or bone density. After reading, you'll know whether L. reuteri is right for you and how to choose a quality product.
TL;DR
- L. reuteri is well-studied for infant colic, H. pylori co-therapy, gut motility, and vitamin D metabolism
- Effective doses range from 1x10^8 to 1x10^10 CFU/day depending on the strain and indication
- The two most researched strains are L. reuteri DSM 17938 and L. reuteri ATCC PTA 6475
- Strain matters more than species — generic "L. reuteri" labels without strain identification are a red flag
- Refrigerated products generally maintain higher viability
Why L. Reuteri Stands Out Among Probiotics
Most probiotic species pass through the gut without colonizing. L. reuteri is different. It produces reuterin, an antimicrobial compound that inhibits pathogenic bacteria while leaving beneficial flora largely intact (Spinler et al., 2008). It also binds to gut epithelial cells more effectively than many other Lactobacillus species, which helps explain its relatively consistent clinical results.
Historically, L. reuteri was present in the gut of most humans. Modern diets, antibiotic use, and food processing have significantly reduced its prevalence (Walter et al., 2011). Supplementation essentially restores a species that was once part of our natural microbiome.
Proven Benefits (What the Evidence Actually Shows)
Infant Colic
This is the strongest evidence area. A meta-analysis of 4 RCTs found that L. reuteri DSM 17938 reduced crying time in breastfed infants with colic by an average of 51 minutes per day compared to placebo (Sung et al., 2018). The typical dose used: 1x10^8 CFU/day in oil drops.
H. Pylori Co-Therapy
When added to standard triple or quadruple antibiotic therapy for H. pylori, L. reuteri improved eradication rates by approximately 9-11% and significantly reduced antibiotic side effects such as diarrhea and nausea (Francavilla et al., 2014). This is not a standalone treatment — it's an adjunct.
Gut Motility and Constipation
In adults with functional constipation, L. reuteri DSM 17938 increased bowel movement frequency by roughly 1-2 additional movements per week compared to placebo (Ojetti et al., 2014). Modest but consistent across trials.
Bone Health
The most surprising finding: L. reuteri ATCC PTA 6475 reduced bone loss in older women with low bone mineral density by 50% over 12 months compared to placebo (Nilsson et al., 2018). This is a single large trial, and replication is still needed, but the mechanism — modulation of TNF-alpha and gut-mediated calcium absorption — is biologically plausible.
Oral Health
L. reuteri reduces levels of Streptococcus mutans (the primary bacterium responsible for dental caries) and reduces gingival bleeding in patients with mild gingivitis (Krasse et al., 2006). Several probiotic lozenges on the market use this strain specifically for oral health.
How to Dose L. Reuteri
| Indication | Strain | Daily Dose | Duration |
|---|---|---|---|
| Infant colic | DSM 17938 | 1x10^8 CFU | 21-28 days |
| H. pylori adjunct | DSM 17938 | 1x10^8 CFU, 2x/day | During antibiotic course |
| Constipation | DSM 17938 | 1x10^8 CFU | 4-8 weeks |
| Bone health | ATCC PTA 6475 | 5x10^9 CFU | 12 months |
| Oral health | DSM 17938 + ATCC PTA 6475 | 2x10^8 CFU | 2-12 weeks |
| General gut support | Any researched strain | 1x10^8 – 1x10^10 CFU | Ongoing |
Take L. reuteri with or just before a meal. The fat content in food improves survival through stomach acid (Dommels et al., 2009).
How to Choose a Quality Product
Check for Strain Identification
The label should list the specific strain (e.g., "L. reuteri DSM 17938"), not just the species name. Different strains have different effects — this is not interchangeable.
CFU Count at Expiration, Not Manufacture
Some products list CFU at time of manufacture, which is meaningless. What matters is the guaranteed count at expiration. Look for "guaranteed through end of shelf life" or similar language.
Storage and Stability
Refrigerated products generally maintain viability better. Shelf-stable formulations exist (using freeze-drying and moisture-barrier packaging) and work well, but they should specify stability testing data.
Product Forms
| Form | Best For | Typical Price (Estonia) |
|---|---|---|
| Oil drops | Infants, precise dosing | €15-25 / 10ml |
| Capsules | Adults, convenience | €12-30 / 30 capsules |
| Chewable tablets | Oral health, children | €10-20 / 30 tablets |
| Powder | Flexible dosing, mixing | €15-25 / 30 servings |
Common Mistakes
1. Choosing by CFU count alone — A product with 50 billion CFU of an unresearched strain is less useful than 100 million CFU of DSM 17938. Strain identity beats raw numbers.
2. Expecting immediate results — Gut colonization takes 1-2 weeks. Clinical trials show effects emerging at 2-4 weeks for most indications.
3. Combining with hot beverages — Heat kills probiotics. Never add L. reuteri to hot tea, coffee, or cooked food.
4. Stopping antibiotics probiotic early — When using as adjunct to H. pylori therapy, continue L. reuteri for at least 1-2 weeks after the antibiotic course ends.
FAQ
Is L. reuteri safe during pregnancy?
Yes. L. reuteri DSM 17938 has been used safely in multiple trials involving pregnant women and neonates. No adverse effects have been reported (Abrahamsson et al., 2007). As always, consult your physician.
Can I get L. reuteri from food?
Small amounts exist in sourdough bread, some fermented dairy products, and breast milk. However, therapeutic doses are difficult to achieve through food alone.
How long should I take L. reuteri?
This depends on the indication. For acute use (colic, H. pylori), 3-8 weeks. For general gut maintenance, ongoing supplementation is common, as colonization typically declines within 1-2 weeks of stopping.
Does L. reuteri help with weight loss?
Some animal studies showed reduced fat mass, but human evidence is weak and inconsistent. Don't buy L. reuteri expecting weight loss benefits.
Can I take L. reuteri with other probiotics?
Yes. L. reuteri is commonly combined with other strains such as L. rhamnosus GG or B. lactis. No antagonistic interactions have been documented.
Estonia-Specific Notes
Probiotic supplements are widely available in Estonian pharmacies (Apotheka, Benu, Südameapteek) and health stores. Prices for L. reuteri products typically range from €10-30 for a monthly supply. BioGaia is the most common brand carrying the DSM 17938 strain in Estonia. Check that products have been stored correctly — especially in summer, pharmacy-bought refrigerated products are more reliable than warehouse-shipped alternatives.
References
- Abrahamsson, T.R. et al. (2007). Probiotics in prevention of IgE-associated eczema: a double-blind, randomized, placebo-controlled trial. Journal of Allergy and Clinical Immunology, 119(5), 1174-1180.
- Dommels, Y.E. et al. (2009). Survival of Lactobacillus reuteri DSM 17938 and Lactobacillus rhamnosus GG in the human gastrointestinal tract. Applied and Environmental Microbiology, 75(9), 3037-3044.
- Francavilla, R. et al. (2014). Lactobacillus reuteri strain combination in Helicobacter pylori infection: a randomized, double-blind, placebo-controlled study. Journal of Clinical Gastroenterology, 48(5), 407-413.
- Krasse, P. et al. (2006). Decreased gum bleeding and reduced gingivitis by the probiotic Lactobacillus reuteri. Swedish Dental Journal, 30(2), 55-60.
- Nilsson, A.G. et al. (2018). Lactobacillus reuteri reduces bone loss in older women with low bone mineral density. Journal of Internal Medicine, 284(3), 307-317.
- Ojetti, V. et al. (2014). The effect of Lactobacillus reuteri supplementation in adults with chronic functional constipation. Journal of Gastrointestinal and Liver Diseases, 23(4), 387-391.
- Spinler, J.K. et al. (2008). Human-derived probiotic Lactobacillus reuteri demonstrate antimicrobial activities targeting diverse enteric bacterial pathogens. Anaerobe, 14(3), 166-171.
- Sung, V. et al. (2018). Lactobacillus reuteri to treat infant colic: a meta-analysis. Pediatrics, 141(1), e20171811.
- Walter, J. et al. (2011). Host-microbial symbiosis in the vertebrate gastrointestinal tract and the Lactobacillus reuteri paradigm. Proceedings of the National Academy of Sciences, 108(Suppl 1), 4645-4652.
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