Lactobacillus reuteri
Summary
L. reuteri effects are strain-specific. DSM 17938 drops reduced crying in breastfed infants with colic across four trials (grade B). ATCC PTA 6475 slowed bone loss slightly in 90 older women but had no effect over 2 years in 239 younger postmenopausal women. Live probiotics carry infection risks for premature babies.
Key facts
- About 25 minutes less crying a day at 21 days; benefit in breastfed, not formula-fed, infants (4 trials, 345 infants)[3]
- Colic drops: 100 million CFU per 5 drops; bone capsules: 10 billion CFU plus 10 mcg vitamin D3 per 2 capsules[8][7]
- FDA warns that preterm infants given probiotics risk invasive, potentially fatal infection[6]
- A benefit from one Lactobacillus strain does not mean another strain will do the same[5]
- 4 graded human outcomes on this page
- October 13, 2026
How it works
ProposedL. reuteri is a lactic acid bacterium that can live in the human gut. Probiotics may help maintain or restore the gut microbial community, produce useful substances and influence immune responses; which of these explains the colic and bone findings is not established. Effects differ between strains.[5][1][3]
What the human research says
Human trials only, one row per outcome. The form column shows what each trial actually tested. Grades follow our evidence-grading policy.
At a glance: strongest evidence per outcome
| Outcome | Grade | Effect | Strongest evidence | Rows |
|---|---|---|---|---|
| Infant colic | Grade B | Improved | Meta-analysis · n = 345 · 2018 | 1 row |
| Bone density | Grade C | Improved | RCT · n = 90 · 2018 | 2 rows |
| Lactose intolerance | Grade D | Improved | RCT · n = 60 · 2010 | 1 row |
Every graded row
| Outcome | Effect | Grade | Best evidence | PMID |
|---|---|---|---|---|
| Crying and fussing time and treatment success at 21 days in infant colic | Improved | Grade B | Meta-analysis · n = 345 · 2018 Infants with colic in 4 double-blind trials (individual participant data) Form: L. reuteri DSM 17938 drops · Dose: Daily drops (the marketed product lists 100 million CFU per 5-drop serving) · Duration: 21 days Crying and fussing fell about 25 minutes a day more than placebo at day 21, and treatment success was 1.7 times as likely. The benefit was large in breastfed infants and not significant in formula-fed infants. | 29279326 (opens PubMed)Source [3] |
| Tibia volumetric bone density over 12 months | Improved | Grade C | RCT · n = 90 · 2018 Women aged 75–80 with low bone density Form: L. reuteri ATCC PTA 6475 · Dose: 10 billion CFU/day · Duration: 12 months Bone density loss at the tibia was smaller than with placebo (−0.83% vs −1.85%; difference about 1 percentage point). Secondary bone measures moved the same way but were not significant. Adverse events did not differ. | 29926979 (opens PubMed)Source [1] |
| Lactose breath-test normalisation, peak breath hydrogen and symptoms | Improved | Grade D | RCT · n = 60 · 2010 Lactose-intolerant patients Form: L. reuteri (also tilactase and placebo arms) · Dose: Twice daily for 10 days before the breath test · Duration: 10 days More patients normalised their breath test and symptom scores improved versus placebo, but less than with tilactase. | 20391953 (opens PubMed)Source [4] |
| Tibia volumetric bone density, hip and spine density and bone turnover over 2 years | No effect | No effect | RCT · n = 239 · 2024 Early postmenopausal women aged 50–60 (Sweden) Form: L. reuteri ATCC PTA 6475 with 200 IU vitamin D3 per capsule · Dose: 5 × 10^8 or 5 × 10^9 CFU twice daily · Duration: 2 years Bone density fell in all groups with no difference from placebo for either dose, and bone turnover markers did not change. No significant adverse effects. | 38865129 (opens PubMed)Source [2] |
Forms
| Form | Elemental % | Absorption (human data) | GI tolerance | Studied for |
|---|---|---|---|---|
| L. reuteri DSM 17938 (drops and chewables) | Varies[8] | Not absorbed; acts in the gut. No head-to-head data versus other strains.[3] | No harmful effects were seen across 4 colic trials (345 infants).[5][3] | Infant colic |
| L. reuteri ATCC PTA 6475 (capsules) | Varies[7] | Not absorbed; acts in the gut. No head-to-head data versus other strains.[1] | Adverse events did not differ from placebo over 1–2 years.[1][2] | Age-related bone loss in women |
Studied doses
Doses studied in human trials ranged from DSM 17938 drops for 21 days in colicky infants to 1 billion or 10 billion CFU a day of ATCC PTA 6475 for 1–2 years in women.[3][1][2]
Interactions
Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.
None found in our sources.
Who should be careful
- Premature infants
- FDA has warned that preterm infants given live probiotics are at risk of invasive, potentially fatal infection; the colic drops label says not for premature infants.[6][8]
- Weakened immune system or serious illness
- The risk of harmful effects from probiotics is greater in people with severe illness or compromised immunity.[5]
- Formula-fed infants with colic
- The colic benefit was not significant in formula-fed babies.[3]
Talk to your pharmacist or clinician before starting a supplement, especially if you take prescription medicines.
Infection risk in vulnerable groups
How to read the label
- Per serving, not per capsuleThe bone product lists 10 billion CFU and 10 mcg (400 IU) vitamin D3 per 2-capsule serving, so each capsule has 5 billion CFU and 5 mcg; the 2018 trial used 10 billion CFU a day.[7][1]
- Check the strainColic evidence is for DSM 17938 and bone evidence for ATCC PTA 6475; a label that only says "L. reuteri" does not tell you which was tested.[3][1][5]
- Drops doseColic drops list 100 million CFU per 5-drop daily serving.[8]
Frequently asked questions
Does L. reuteri help infant colic?
The DSM 17938 strain reduced crying by about 25 minutes a day at 21 days in an analysis of 4 trials, mainly in breastfed babies.[3]
Does L. reuteri protect bones?
Evidence is mixed: ATCC PTA 6475 slightly slowed bone loss in women aged 75–80 over 1 year, but a 2-year trial in women aged 50–60 found no effect.[1][2]
Is L. reuteri safe for babies?
No harmful effects were seen in the colic trials, but FDA warns that live probiotics can cause serious infection in premature infants, and colic drops are labelled not for premature babies.[5][6][8]
How many CFU are in a bone-health capsule?
One product lists 10 billion CFU per 2-capsule serving, or 5 billion per capsule, plus vitamin D3.[7]
Does any L. reuteri strain work the same way?
No. Probiotic effects are strain-specific, so results for DSM 17938 or ATCC PTA 6475 do not carry over to other strains.[5]
Sources
- [1]Lactobacillus reuteri reduces bone loss in older women with low bone mineral density: a randomized, placebo-controlled, double-blind, clinical trial.. J Intern Med, 2018. RCT
- [2]Limosilactobacillus reuteri 6475 and Prevention of Early Postmenopausal Bone Loss: A Randomized Clinical Trial.. JAMA Netw Open, 2024. RCT
- [3]Lactobacillus reuteri to Treat Infant Colic: A Meta-analysis.. Pediatrics, 2018. meta-analysis
- [4]The effect of oral supplementation with Lactobacillus reuteri or tilactase in lactose intolerant patients: randomized trial.. Eur Rev Med Pharmacol Sci, 2010. RCT
- [5]Probiotics: Usefulness and Safety. National Center for Complementary and Integrative Health (NCCIH), 2019. fact-sheet
- [6]Risk of Invasive Disease in Preterm Infants Given Probiotics Formulated to Contain Live Bacteria or Yeast. U.S. Food and Drug Administration, 2023. safety-communication
- [7]Osfortis (BioGaia), DSLD label 311009: L. reuteri ATCC PTA 6475, 10 billion CFU plus 10 mcg vitamin D3 per 2-capsule daily serving (one capsule twice daily); adults. NIH Office of Dietary Supplements, Dietary Supplement Label Database, 2024. label
- [8]Protectis Baby Drops (BioGaia), DSLD label 311013: L. reuteri DSM 17938, 100 million CFU per 5-drop daily serving; not intended for premature infants. NIH Office of Dietary Supplements, Dietary Supplement Label Database, 2024. label
- [9]Probiotics for infantile colic: Is there evidence beyond doubt? A meta-analysis and systematic review.. Acta Paediatr, 2024. meta-analysis
What changed
- Strict adversarial pass: PMIDs re-checked; Osfortis DSLD amounts verified per 2-capsule serving (10 billion CFU + 10 mcg D3). The null 2-year bone trial is shown beside the positive 1-year trial; FDA preterm-infant warning and NCCIH immune-compromise caution included.
- First draft rebuilt from scratch after the earlier draft files were lost. Every PMID checked against NCBI esummary and abstracts read for each row. Osfortis label re-read from the DSLD API: 10 billion CFU and 10 mcg vitamin D3 are per 2-capsule serving (5 billion CFU and 5 mcg per capsule). Safety from the NCCIH probiotics fact sheet and the 2023 FDA preterm-infant safety communication.