Last verified: 8 days ago
Lactobacillus reuteri
Also known as: L. reuteri, Limosilactobacillus reuteri, L. reuteri DSM17938, L. reuteri LMG P-27481
Evidence under review. — Not yet rated
Probiotic bacteria with clinical evidence for infant colic, gum disease, and gut health in children.
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What it does
Lactobacillus reuteri is a naturally occurring probiotic bacterium found in the human gut. Clinical trials show it significantly reduces crying time in colicky infants, and early supplementation...
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Evidence quality
Evidence base hasn't been formally rated yet. See research below.
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Clinical dose
1×10⁹ CFU/day based on clinical study data
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Found in
BioGaia Gastrus IBS, HUM Nutrition Private Party, BioGaia Protectis Baby Probiotic Drops and 1 more
What the Science Says
Lactobacillus reuteri is a naturally occurring probiotic bacterium found in the human gut. Clinical trials show it significantly reduces crying time in colicky infants, and early supplementation may dramatically lower the risk of functional abdominal pain years later. In adults, it has been shown to reduce gum inflammation, lower inflammatory markers like TNF-α and IL-6, and improve outcomes in periodontitis when used alongside standard dental treatment.
What It Doesn't Do
Not proven to treat cancer in humans — animal and lab studies only. No solid evidence it cures obesity or liver disease on its own. Not a replacement for dental cleaning or standard medical care. Benefits are strain-specific — not all L. reuteri products are the same.
Evidence-Based Benefits
Reduces crying time in colicky infants and may lower risk of abdominal pain at age 10.
Moderate EvidenceEffective at: Strain-specific; DSM17938 or LMG P-27481 studied
Supporting studies (click to view on PubMed):
Reduces gum inflammation, probing depth, and inflammatory markers in periodontitis patients.
Moderate EvidenceEffective at: 1×10⁹ CFU/day for 8 weeks
Supporting studies (click to view on PubMed):
Helps reduce duration of diarrhea and symptoms of acute gastroenteritis in children.
Moderate EvidenceEffective at: Strain and dose vary; see individual product labeling
Supporting studies (click to view on PubMed):
Modulates mucosal immune gene expression, promoting immune tolerance in infants.
Weak EvidenceEffective at: Strain-specific; LMG P-27481 studied
Supporting studies (click to view on PubMed):
Absorption & Bioavailability
Unknown for systemic absorption; survives gut transit as a live organism. Strain and formulation matter significantly for colonization and effect.
Red Flags to Watch For
- Strain specificity matters — DSM17938 and LMG P-27481 are the best-studied strains; generic 'L. reuteri' products may not replicate study results
- Most dramatic infant colic and long-term gut benefits come from early-life supplementation — adult benefits may differ
- Oral/dental studies are small and short-term; long-term dental benefits are not yet established
- Cancer-related findings are from mouse models and engineered bacteria combinations — do not apply to standard probiotic supplements
Products Containing Lactobacillus reuteri
See how Lactobacillus reuteri is used in these analyzed products:
Frequently Asked Questions
What does Lactobacillus reuteri do?
Probiotic bacteria with clinical evidence for infant colic, gum disease, and gut health in children.
What is the effective dose of Lactobacillus reuteri?
1×10⁹ CFU/day based on clinical study data
Is Lactobacillus reuteri safe?
Strain specificity matters — DSM17938 and LMG P-27481 are the best-studied strains; generic 'L. reuteri' products may not replicate study results
What doesn't Lactobacillus reuteri do?
Not proven to treat cancer in humans — animal and lab studies only.
Research Sources
- PubMed
- NIH DSLD
This information is for educational purposes only and is not medical advice. Always consult a healthcare professional before starting any supplement regimen. Last updated: 2026-06-03