Lactobacillus Reuteri for Kids: What Every Parent Should Know
📋 In This Article
✦ Key Takeaways
- L. reuteri is a naturally occurring probiotic strain found in breast milk and fermented foods.
- DSM 17938 is the most researched strain for children — look for it on labels.
- Clinical evidence supports its use for colic, diarrhea, and constipation in kids.
- Safe at normal doses for infants through school-age children when used correctly.
- Always consult your pediatrician before starting any probiotic supplement.
If you've ever typed "is Lactobacillus reuteri safe for kids" into a search bar at midnight while a crying infant refused to settle, you're not alone. Lactobacillus reuteri — now officially reclassified as Limosilactobacillus reuteri — is one of the most studied probiotic strains in pediatric research. Unlike the broad, multistrain blends crowding supplement shelves, L. reuteri comes with a genuine body of clinical evidence specifically in children. Here's what we know, and what parents actually need to consider.
What Is Lactobacillus Reuteri?
Lactobacillus reuteri is a lactic acid-producing bacterium that naturally colonizes the human gastrointestinal tract. It's one of the few probiotic species that has evolved alongside humans — found in breast milk, fermented dairy foods like kefir and yogurt, and in the gut microbiomes of healthy people worldwide.
What makes L. reuteri stand out among probiotic strains is its ability to produce reuterin, a broad-spectrum antimicrobial compound that helps suppress harmful bacteria without disturbing the broader microbiome ecosystem. It also produces short-chain fatty acids and B vitamins that support gut lining integrity.
For children specifically, L. reuteri has been studied across multiple pediatric populations — from premature newborns to school-age children — with a safety profile that makes it one of the better-characterized probiotic options for parents to consider.
Research-Backed Benefits for Children
Not all probiotics do the same job. L. reuteri has been specifically investigated in pediatric clinical trials, giving us more confidence than we can place in many other strains. Here's what the evidence actually says:
1. Infant Colic Relief
A meta-analysis published in the journal Pediatrics (American Academy of Pediatrics) reviewed seven randomized controlled trials and found that L. reuteri DSM 17938 significantly reduced crying time in breastfed infants with colic compared to placebo — an average of 43 fewer minutes of crying per day by week 3. A 2014 BMJ paper confirmed these findings, cementing L. reuteri as the most evidence-supported probiotic intervention for infant colic currently available.
2. Childhood Diarrhea Recovery
Research published in Nature Reviews Gastroenterology & Hepatology found that L. reuteri supplementation reduced episodes of diarrhea in healthy children attending daycare. A 2020 review in the International Journal of Pediatrics corroborated this: L. reuteri DSM 17938 was associated with shorter duration of acute infectious diarrhea in children ages 6 months to 3 years.
3. Constipation Support
A 2010 Italian study (published in NutraIngredients) found L. reuteri beneficial for chronic infant constipation. A SpringerLink-published European pediatric review found that children with functional constipation who received L. reuteri DSM 17938 had significantly more spontaneous bowel movements per week than those given placebo, with no adverse effects reported.
4. Immunity & Reducing Infections
A Wageningen University review of probiotic supplementation in children found associations between L. reuteri use and reduced frequency of upper respiratory tract infections. BioGaia's combination L. reuteri study found that children receiving the probiotic had a shorter duration of sore throat symptoms. While more studies are needed, the gut-immune axis mechanism is well-established — roughly 70% of immune cells reside in or near the gut lining.
5. Oral Health
L. reuteri has been studied for its dental benefits: some research (including data from BioGaia's Prodentis line) suggests the strain may reduce levels of Streptococcus mutans, a primary cause of tooth decay, when used as a chewable tablet. While not a substitute for good brushing habits, this is a promising secondary benefit some parents find appealing.
The DSM 17938 Strain — Why This Number Matters
Probiotics aren't interchangeable. The clinical evidence for L. reuteri is almost entirely built on one specific strain: DSM 17938 (also marketed as BioGaia ProTectis). When you see a product claiming "Lactobacillus reuteri" benefits, the important question is: which strain?
The strain name typically looks like Lactobacillus reuteri DSM 17938 or L. reuteri ATCC PTA 5289. These codes identify the exact bacterial deposit — and the difference between strains can be as significant as the difference between species.
| Strain Identifier | Primary Research Use | Form |
|---|---|---|
| DSM 17938 | Colic, diarrhea, constipation in infants & children | Drops, chewable tablets |
| ATCC PTA 5289 | Oral health, dental cavity prevention | Chewable lozenges |
| ATCC PTA 6475 | Adult bone health, anti-inflammatory (less pediatric research) | Capsules |
For children, DSM 17938 is the strain with the richest pediatric evidence base. When shopping for a lactobacillus reuteri supplement for kids, look for this strain designation on the label.
How Much L. Reuteri Is Safe for Kids?
Dosage in clinical trials for children has generally ranged from 100 million to 1 billion CFU (colony-forming units) per day. Most pediatric L. reuteri products — including BioGaia ProTectis chewable tablets, which contain DSM 17938 — provide around 100 million CFU per dose.
| Age Range | Typical Dose Used in Research | Form |
|---|---|---|
| Newborn – 12 months | ~100 million CFU/day (5 drops) | Probiotic oil drops |
| 1 – 4 years | ~100–500 million CFU/day | Drops or chewable tablet |
| 5 – 12 years | ~100 million – 1 billion CFU/day | Chewable tablets or capsule |
These are general ranges drawn from clinical literature. The right dose for your child depends on their age, health status, and reason for supplementation. Always consult your pediatrician before starting L. reuteri supplementation — especially for infants under 12 months or children with compromised immune function.
Natural Food Sources of L. Reuteri
One of the most common parent questions is: "What foods contain Lactobacillus reuteri?" The short answer is that L. reuteri is not abundant in most commercially available fermented foods the way other probiotic strains (like L. acidophilus) are. However, it does naturally occur in small amounts in:
- Breast milk — one of the original sources; L. reuteri is transmitted during breastfeeding
- Some artisan-style fermented dairy — certain traditionally made yogurts and kefirs (especially from raw or small-batch producers)
- Sourdough bread — fermentation can include L. reuteri, though heat kills live bacteria during baking
- Some aged cheeses — Parmesan, Gouda, and similar hard cheeses have trace amounts
The practical reality: to get therapeutic doses of L. reuteri DSM 17938 consistently, a targeted supplement is the most reliable approach. Food sources, while valuable for microbiome diversity in general, don't provide the specific strain or dose used in research.
How to Choose an L. Reuteri Supplement for Kids
The market for children's probiotics is crowded — and many products don't specify strain, CFU count at expiration, or whether the product is shelf-stable. Here's what to look for when selecting a lactobacillus reuteri chewable for kids or drops for infants:
✓ Strain Specificity
The label should clearly state the strain: "Lactobacillus reuteri DSM 17938" or "Limosilactobacillus reuteri DSM 17938." Generic "Lactobacillus reuteri" without a strain code is a red flag.
✓ CFU Count At Expiration
Look for products that state CFU count "at expiration" — not "at manufacture." Probiotic bacteria die over time; you want to know what's alive when it reaches your child.
✓ Age-Appropriate Form
Infants under 12 months: oil drops are standard (can be added to breast milk or formula before feeding). Toddlers 1–3: drops or dissolvable tablets. Children 4+: chewable tablets are well-tolerated and widely studied.
✓ No Unnecessary Additives
Look for simple formulas — especially for infants. Avoid products with artificial colors, high sugar content, or unnecessary fillers.
✓ Third-Party Testing
For any supplement given to a child, third-party testing by NSF, USP, or Informed Sport provides independent verification that the product contains what the label claims.
Frequently Asked Questions
Is Lactobacillus reuteri safe for kids?
Is Lactobacillus reuteri harmful to children?
Which probiotic is best for kids — L. reuteri or L. rhamnosus?
What foods naturally contain Lactobacillus reuteri?
How long does it take for L. reuteri to work in kids?
The Bottom Line
Lactobacillus reuteri — specifically the DSM 17938 strain — is one of the most evidence-backed probiotics in pediatric research, with clinical support for colic, diarrhea, constipation, and immune health in children. When choosing a supplement, strain specificity matters: look for "DSM 17938" on the label, opt for CFU counts stated at expiration, and choose age-appropriate forms. As with any supplement for children, conversation with your pediatrician is the best first step.
