Lactobacillus reuteri

bacteriapantetheine

What is it

Lactobacillus reuteri (now reclassified as Limosilactobacillus reuteri) is a probiotic bacterium found naturally in the human gut and breast milk. It has been studied for infant colic, oral health, gut health, and immune support, with different strains having different documented effects.

How it works

L. reuteri colonizes the gastrointestinal tract and produces reuterin, an antimicrobial compound derived from glycerol that inhibits the growth of many pathogenic bacteria, yeasts, and protozoa. It also produces lactic acid and short-chain fatty acids that lower local pH, supporting a healthy microbial environment. The bacterium adheres to intestinal epithelial cells and modulates immune signaling, reducing pro-inflammatory cytokine production while supporting regulatory T-cell development. Some strains have been shown to strengthen intestinal barrier integrity and influence enteric nervous system signaling, which may underlie observed effects on gut motility and visceral sensitivity. Different L. reuteri strains have markedly different documented uses. Strain DSM 17938 has been most extensively studied for infant colic and regurgitation. Strain NCIMB 30242 has been studied for cardiovascular markers. Strain ATCC PTA 5289 has oral health applications, including gum health.

Evidence for 5 uses

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

Infant colic

Grade B

Good evidence

Multiple trials of L. reuteri DSM 17938 in exclusively or predominantly breastfed colicky infants show reduced daily crying time. Effects are less consistent in formula-fed infants. Generally considered safe for healthy term infants.

Functional gastrointestinal symptoms in infants

Grade C

Moderate evidence

Small trials suggest L. reuteri DSM 17938 may reduce regurgitation frequency and improve gastric emptying in infants with functional GI symptoms.

Helicobacter pylori eradication (adjunct)

Grade C

Moderate evidence

L. reuteri may modestly improve H. pylori eradication rates when added to standard antibiotic therapy and reduce treatment-related side effects. Evidence varies by strain and protocol.

Gingivitis and oral health

Grade C

Moderate evidence

Specific L. reuteri strains delivered via lozenges or chewing tablets show modest reduction in gum inflammation and dental plaque in small trials.

LDL cholesterol

Grade C

Moderate evidence

L. reuteri NCIMB 30242 has shown modest LDL cholesterol reductions in adult trials. Effect size is smaller than statin therapy but may have additive value in mild dyslipidemia.

3 commercial forms

L. reuteri DSM 17938

Acid-stable, well-studied in infants

Most studied strain for infant colic and digestive symptoms. Available as oil-based drops for infants.

L. reuteri NCIMB 30242

Bile-salt hydrolase activity

Studied for cardiovascular markers including LDL cholesterol reduction in adults.

L. reuteri ATCC PTA 5289

Designed for oral cavity adhesion

Used in lozenges and chewing tablets for gum and oral health.

Dosage

There is no RDA for probiotics. Clinical doses for L. reuteri vary by strain. For infant colic, DSM 17938 has been studied at 100 million to 1 billion CFU per day. For adult cardiovascular use, NCIMB 30242 has been studied at 2.9 billion CFU twice daily. General adult supplements range from 1 to 10 billion CFU per day.

When and how to take it

L. reuteri can be taken with or without food. For infants, drops are typically given once daily. For adult supplements, take consistently at the same time each day. Taking with a small meal may improve survival through the stomach. For oral health strains, lozenges or chewable tablets should be allowed to dissolve in the mouth for maximum contact with oral surfaces. Separate from antibiotics by at least 2 hours.

Food sources

Food	Amount	%DV
Some fermented dairy products	Variable; not all yogurts or kefirs contain L. reuteri	—
Sourdough breads (some)	Variable; mostly killed during baking	—
Human breast milk	Natural source for infants	—

Safety

L. reuteri is generally well tolerated, including in infants. Mild gas, bloating, or stool changes can occur initially. Serious adverse events are rare in healthy people but, as with other live probiotics, include bacteremia in immunocompromised individuals. No established Tolerable Upper Intake Level. Long-term safety in infants appears favorable in available trials.

Who should be cautious

People who are severely immunocompromised, those with central venous catheters, and critically ill patients should consult their physician before taking live probiotics. For infant use, L. reuteri DSM 17938 has been studied in healthy term infants; preterm and critically ill infants should only receive probiotics under specialist supervision. Pregnant and breastfeeding women appear to tolerate L. reuteri well.

Interactions

Antibiotics will kill probiotic organisms; separate by at least 2 hours. Immunosuppressive drugs may increase the small risk of bacterial translocation. No well-documented interactions with most supplements. Concurrent use with other live probiotic blends has not been thoroughly evaluated for combined effects.

Frequently asked questions

Is L. reuteri safe for infants?⌄

L. reuteri DSM 17938 has been studied in healthy term infants and is generally considered safe. Discuss with your pediatrician before giving any supplement to an infant, especially preterm or medically fragile babies.

Does L. reuteri actually help with colic?⌄

Multiple trials show reduced crying time in breastfed colicky infants. Effects are smaller and less consistent in formula-fed babies. It is one of the better-studied options, but results vary by individual.

Can L. reuteri lower cholesterol?⌄

The NCIMB 30242 strain has shown modest LDL cholesterol reductions in trials. The effect is small compared to statins but may complement dietary changes for mild dyslipidemia.

How is L. reuteri different from L. rhamnosus?⌄

They are different species with different metabolic profiles and documented uses. L. reuteri produces reuterin, an antimicrobial; L. rhamnosus has different surface proteins and stronger evidence for acute diarrhea.

Should I refrigerate L. reuteri drops?⌄

Check label directions. Some L. reuteri products are shelf-stable; others require refrigeration to maintain potency.

References

ChEBI: pantetheine — ChEBI Database link
Wikidata: Limosilactobacillus reuteri — Wikidata link

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Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you're pregnant, breastfeeding, on medications, or managing a chronic condition.