Its ID gene (16S) · each bar is one letter A C G T NCBI 16S
What's this?
Zoomed in: letters 115–138
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  2. G
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Its ID gene: the stretch scientists read to tell microbes apart. Each bar is one letter of its DNA. Every species has its own order of letters, so the pattern works like a fingerprint. Close relatives share most of it.

16S rRNA gene, V4 region: the 253 letters between the standard primers (515F/806R), which are the same in every species. One reference sequence; strains can differ by a letter or two. NCBI NR_201926.1

NCBI Taxonomy 1598 Plate · Bacillota

Limosilactobacillus reuteri

Formerly Lactobacillus reuteri.

  • Can make lactic acid
  • Can ferment fiber
  • Can use lactose
Also known as Lactobacillus reuteriLactobacillus fermentum subsp. reuteri
Lab traits Gram +Rod-shapedNon-motileMicroaerophile Lab-tested · BacDive
The whole of its DNA, to scale

Its genome

Genome · 2.1 million letters · 39% G+C
Shortest we have Mycoplasmoides genitalium 0.6M
⋮ 395 shorter
Limosilactobacillus average 1.9M
Limosilactobacillus reuteri 2.1M
⋮ 1,956 longer
Longest we have Bradyrhizobium altum 9.8M

Small for a gut microbe: longer than 17% of the 2,354 we have genomes for.

39% G+C, higher than 23% of gut microbes.

To scale: if its ID gene were 1 cm long, its genome would stretch 14 meters. Yours would stretch 21 kilometers. One reference genome; strains vary. NCBI GCF_000439275.1

Capabilities, not measurements of anyone's gut

What it can do

Makes
  • Can make lactic acid What yogurt bacteria make; other microbes turn it into butyrate.
  • Can make B vitamins Folate, B12, riboflavin and others.
Eats
  • Can ferment fiber Breaks down dietary fiber that our own enzymes can't.
  • Can use lactose The sugar in milk and dairy.
Changes
  • Can change bile acids Modifies the bile acids the liver makes to digest fat. 2 of 14 strains can

Not seen in its genomes or lab tests: make butyrate, make propionate, eat inulin, eat resistant starch, eat pectin, feed on gut mucus, make hydrogen sulfide, make methane.

All 13 capabilities and their evidence
CapabilityVerdict Genome analysis Lab tests Published research
Can make butyrateNot seen0 of 14 genomes—No papers
Can make propionateNot seen0 of 14 genomes—No papers
Can make lactic acidCan14 of 14 genomes—Papers say yes
Can ferment fiberCan14 of 14 genomes11 of 21 strains · strip test Papers say yes
Can eat inulinNot seen0 of 14 genomes0 of 14 strains · strip test No papers
Can eat resistant starchNot seen0 of 14 genomes—No papers
Can eat pectinNot seen0 of 14 genomes—No papers
Can use lactoseCan0 of 14 genomes12 of 13 strains Papers say yes
Can feed on gut mucusNot seen0 of 14 genomes—No papers
Can change bile acidsSome strains2 of 14 genomes—No papers
Can make B vitaminsCan14 of 14 genomes—Papers say yes
Can make hydrogen sulfideNot seen0 of 14 genomes—No papers
Can make methaneNot seen0 of 14 genomes—No papers

AGORA2 (Heinken et al. 2023) via VMH, CC BY 4.0 · BacDive (DSMZ), CC BY 4.0 · NJC19 (Lim et al., Scientific Data 2020), CC0

What’s typical · a description, not a comparison

In healthy guts

Everyone · 12,213 people · 129 studies
How common

Found in under 1% of healthy people.

How big a slice of the gut
  1. largest Segatella copri 6.2%
  2. 2nd largest Phocaeicola vulgatus 5.0%
  3. 3rd largest Faecalibacterium prausnitzii 4.7%
  4. 4th largest Bacteroides uniformis 3.2%
  5. 5th largest Agathobacter rectalis 2.5%
  6. 6th largest Alistipes putredinis 2.3%
  7. 7th largest Bifidobacterium longum 2.1%
  8. 8th largest Ruminococcus bromii 1.8%
  9. Limosilactobacillus reuteri under 0.01%
  10. 2,169 other microbes, each a sliver 56.7%
  11. 15.6%

On average, a sliver, under 0.01% of the microbes in a healthy gut.

By age and sex

Every group, drawn the same way. Only some samples record age or sex, so each group says how many people it comes from. Tap one to see it above.

By age
367 people · 2.7% carry it under 0.01% of the microbes
198 people · 5 studies 0% carry it 0.00% of the microbes
57 people · 0% carry it 0.00% of the microbes
1,283 people · 27 studies under 1% carry it under 0.01% of the microbes
142 people · 15 studies 1.4% carry it under 0.01% of the microbes
By sex
2,063 people · under 1% carry it under 0.01% of the microbes
1,530 people · 29 studies under 1% carry it under 0.01% of the microbes

Where these numbers come from

Who
12,213 healthy people from 129 studies in GMrepo, by its own “Health” label. Whole-genome sequencing only; one sample is one person.
How common
The share of them whose sample has any of it.
Slice
Its average share of the microbes in a healthy gut, across everyone, carriers or not. The slices add up to 84.4%: the rest is reads GMrepo couldn’t place at this rank, shown as “Not identified to a species”.
Age and sex
From the samples that record them (about 17% record an age and 29% a sex). A group with fewer than 50 people isn’t shown.
Ranks
A slice’s rank is a place among the 2,178 microbes we have numbers for, within the group shown: exact in the top 10, then rounded bands.
Analysis
Ours, of GMrepo’s per-sample data. GMrepo on Data sources
The 129 studies behind these numbers

Largest first by people. Each is a GMrepo project.

StudyPeopleWith ageWith sex
A study in the United States PRJNA695570 ↗ 1,767 0 1,759
A study in Japan PRJNA1077400 ↗ 1,268 0 0
A study in Spain PRJEB61680 ↗ 839 0 0
Zhong et al. 2019 · the Netherlands PRJEB26795 ↗ 572 0 0
A study in the Netherlands PRJNA942468 ↗ 517 0 0
Shang et al. 2021 · Australia PRJNA492716 ↗ 370 0 84
A study in the United States PRJNA398089 ↗ 363 237 363
A study in the United States PRJNA795985 ↗ 290 0 0
Zhang et al. 2022 · China PRJNA801051 ↗ 239 0 0
A study in Ireland PRJEB46398 ↗ 237 0 0
Valles-Colomer et al. 2023 · Italy PRJEB63351 ↗ 225 0 0
A study in the United States PRJNA633576 ↗ 225 223 0
Lee et al. 2024 · the United Kingdom PRJEB52380 ↗ 177 0 0
A study in the United States PRJEB37924 ↗ 164 0 0
A study in China PRJNA542578 ↗ 151 0 0
A study in the United States PRJNA993675 ↗ 142 142 142
Lee et al. 2022 · South Korea PRJEB45443 ↗ 112 0 0
A study in China PRJEB65297 ↗ 111 0 0
A study in India PRJNA397112 ↗ 110 110 0
A study in Japan PRJDB13214 ↗ 105 0 0
A study in China PRJNA686835 ↗ 104 0 0
A study in China PRJNA763023 ↗ 100 0 0
A study in China PRJNA994318 ↗ 100 0 0
A study in the United States PRJEB28543 ↗ 96 96 96
A study in Italy PRJNA716780 ↗ 94 94 94
A study in China PRJNA509999 ↗ 93 0 0
A study in the United States PRJNA878603 ↗ 92 92 92
Guo et al. 2023 · the United States PRJNA751448 ↗ 91 91 91
A study in China PRJNA793776 ↗ 89 89 89
A study in China PRJNA888860 ↗ 88 0 0
A study in Ireland PRJEB15388 ↗ 85 0 0
A study in China PRJNA731589 ↗ 85 85 0
A study in Israel PRJNA994433 ↗ 80 80 0
A study in Canada PRJNA521587 ↗ 79 78 79
La Reau et al. 2023 · the United States PRJNA917645 ↗ 76 0 0
Pomyen et al. 2023 · Thailand PRJNA932948 ↗ 76 0 76
A study in the United States PRJEB53403 ↗ 75 45 45
Eriksen et al. 2023 · Sweden PRJNA633381 ↗ 74 0 0
A study in China PRJNA356102 ↗ 72 0 0
A study in China PRJNA689961 ↗ 70 0 0
A study in China PRJNA449784 ↗ 69 0 0
Duru et al. 2024 · Finland PRJEB59350 ↗ 66 0 0
Roth-Schulze et al. 2021 · Australia PRJNA604850 ↗ 66 66 48
Wan et al. 2024 · China PRJNA1037036 ↗ 64 64 64
A study in China PRJNA686821 ↗ 64 0 0
Fulcher et al. 2022 · the United States PRJNA836336 ↗ 64 0 0
Hu et al. 2023 · China PRJNA893406 ↗ 64 0 0
A study in Italy PRJNA553191 ↗ 62 0 0
Wilson et al. 2024 · the United States PRJEB59709 ↗ 59 0 0
A study in the United States PRJNA822660 ↗ 58 58 58
A study in the United States PRJNA314903 ↗ 50 0 0
A study in the United States PRJNA379741 ↗ 50 0 50
A study in China PRJNA674716 ↗ 50 0 0
A study in China PRJNA762484 ↗ 49 20 21
Yan et al. 2023 · China PRJNA808806 ↗ 48 0 0
Stockdale et al. 2022 · Ireland PRJNA813736 ↗ 48 40 41
Tao et al. 2025 · China PRJNA1135717 ↗ 47 0 0
A study in the United States PRJNA660443 ↗ 44 0 0
A study in China PRJNA946183 ↗ 44 0 0
A study in China PRJNA530971 ↗ 43 0 0
Ye et al. 2023 · China PRJNA853814 ↗ 42 42 0
A study in China PRJNA943232 ↗ 42 42 42
A study in the United Kingdom PRJEB17978 ↗ 41 0 0
A study in China PRJNA588035 ↗ 39 0 0
A study in China PRJNA349463 ↗ 33 0 0
A study in India PRJNA531203 ↗ 31 0 0
A study in Switzerland PRJEB24557 ↗ 30 0 0
A study in India PRJNA792685 ↗ 30 0 0
A study in China PRJNA808649 ↗ 30 30 30
Pötgens et al. 2024 · Belgium PRJNA813705 ↗ 30 0 0
Grion et al. 2024 · Spain PRJNA961076 ↗ 30 0 0
A study in Canada PRJEB21933 ↗ 29 0 0
A study PRJEB32767 ↗ 29 0 0
A study in the United States PRJEB53401 ↗ 29 29 29
A study in Poland PRJNA1125836 ↗ 28 28 28
Chen et al. 2023 · China PRJEB55711 ↗ 27 0 0
A study in the United States PRJNA629755 ↗ 27 0 0
A study in China PRJNA818062 ↗ 27 0 0
Wang et al. 2023 · China PRJNA905444 ↗ 27 0 0
A study in Spain PRJEB62571 ↗ 26 0 0
A study in China PRJNA769284 ↗ 26 0 0
Lv et al. 2024 · China PRJEB52189 ↗ 25 0 0
Xiao et al. 2024 · China PRJNA938297 ↗ 25 25 25
A study in Germany PRJEB76677 ↗ 24 0 0
Elie et al. 2023 · France PRJNA648321 ↗ 24 0 0
A study in Mali PRJNA936589 ↗ 24 0 0
A study in the United States PRJNA1044118 ↗ 23 0 0
A study in Turkey PRJNA1167935 ↗ 23 0 0
A study in Russia PRJNA762199 ↗ 23 23 23
Ievina et al. 2024 · Latvia PRJEB80379 ↗ 22 0 0
A study in China PRJNA896336 ↗ 22 0 0
A study in China PRJNA688881 ↗ 21 0 0
Edwinson et al. 2022 · the United States PRJNA705217 ↗ 21 21 21
A study in France PRJEB55534 ↗ 20 0 0
A study in Canada PRJNA1022308 ↗ 20 0 0
A study in China PRJNA1138893 ↗ 20 0 0
Schaefer et al. 2022 · the United States PRJNA800662 ↗ 20 0 0
Ding et al. 2023 · China PRJNA999028 ↗ 20 0 0
A study in the United States PRJEB42155 ↗ 18 0 0
A study in Japan PRJNA665854 ↗ 18 0 0
A study in Canada PRJNA742740 ↗ 17 0 0
Stockdale et al. 2022 · the United States PRJNA626004 ↗ 16 0 0
A study in China PRJNA858062 ↗ 16 16 16
A study in China PRJNA429990 ↗ 15 0 0
Wan et al. 2019 · China PRJNA532538 ↗ 15 0 0
A study in China PRJNA624223 ↗ 15 15 15
A study in the United States PRJNA634145 ↗ 15 15 15
A study in China PRJNA734379 ↗ 15 0 15
Sadeghi et al. 2024 · France PRJEB70916 ↗ 14 14 14
A study in Singapore PRJNA272371 ↗ 14 14 14
A study in India PRJNA983946 ↗ 14 14 14
A study in Sweden PRJEB38997 ↗ 13 0 0
Seishima et al. 2019 · Japan PRJNA511372 ↗ 13 0 0
A study in China PRJEB54728 ↗ 12 0 0
A study in Switzerland PRJEB13835 ↗ 11 0 0
A study in Japan PRJNA846495 ↗ 11 0 0
Joensen et al. 2017 · Denmark PRJEB14038 ↗ 10 0 0
A study in the United Kingdom PRJEB53891 ↗ 10 0 0
A study in Iran PRJNA1050885 ↗ 10 0 0
A study in China PRJNA730640 ↗ 10 0 0
A study in Israel PRJNA939026 ↗ 10 9 0
Ye et al. 2023 · China PRJNA993632 ↗ 10 0 0
A study in China PRJNA1024678 ↗ 9 0 0
Wang et al. 2024 · Switzerland PRJNA363003 ↗ 9 0 0
A study in the United States PRJNA613834 ↗ 9 0 0
A study in the United States PRJNA896226 ↗ 8 0 0
A study in Spain PRJNA1029046 ↗ 7 0 0
A study in China PRJNA492189 ↗ 5 0 0
A study in France PRJNA287878 ↗ 2 0 0
Compared within studies that had both

In conditions

Compared with healthy people in the same studies, it’s less common in none and more common in none. Only studies that had both are counted.

A difference is an association: it doesn’t mean this microbe causes, prevents or treats any of these.

Where these numbers come from

Studies
Only GMrepo projects that had people with the condition and healthy people, 10 or more of each. Numbers come from those studies, never from pooling.
How common
The share of people whose sample has any of it, in the people with the condition and in the healthy people of those same studies. Tested within studies (Cochran–Mantel–Haenszel, corrected for testing many microbes); a difference counts when it is clear and meaningful (Cohen’s h of 0.2 or more).
Strength word
Counted by code from how many studies point the same way: Seen again and again (3 or more, none clearly the other way), Seen more than once (2, the majority), Seen once (1, listed last). Where studies disagree, a row isn’t listed.
Each study
Tap a row for every study’s own numbers, and for how much carriers have.
Analysis
Our analysis of GMrepo data. GMrepo on Data sources · Read the rules

Also compared · 2 conditions

Compared within studies that had both, but not listed above.

No meaningful difference · 2

PubMed · human studies and reviews first

Recent research

All research on it
  1. Systematic review Frontiers in dental medicine · 2026
    Effect of probiotic interventions on oral health in children: a systematic review.
    PubMed ↗
  2. PubMed ↗
  3. PubMed ↗
  4. PubMed ↗
  5. PubMed ↗

Source: PubMed, U.S. National Library of Medicine · 1,901 linked papers, last 10 years

In people · from PubMed and product labels

Strains studied

How much each strain has been studied in people, not whether it works. Many trials test a strain inside a blend, so those are counted apart, and reviews are summaries of trials, so they're never counted as more trials.

24 strains of L. reuteri are named on product labels. 6 have human trials; 18 have none found yet, including UALre-16, which is in 28 products.

  1. L. reuteri DSM 17938

    In 7 products → Hide papers ▴
    107 human trials · 23 reviews 88 single-strain · 19 in blends
    Newest first Single strain only Trials only Titles and links only, never abstracts
    1. Meta-analysis Nutrients · 2026 Single strain
      Efficacy and Safety of Lactobacillus reuteri DSM 17938 in Pediatric Functional Abdominal Pain Disorders: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. PubMed ↗
    2. Meta-analysis Nutrition · 2026 Single strain
      Efficacy of Lactobacillus reuteri DSM 17938 in preterm newborns and infants with colic: a systematic review and meta-analysis of randomized controlled trials. PubMed ↗
    3. Randomized trial Pathogens · 2026 Single strain
      Nutritional Stunting Is Linked to Reduced Oral Microbiome Stability and Reconfigured Microbial Networks in Children: A Pilot Intervention Study. PubMed ↗
    4. Systematic review Frontiers in nutrition · 2026 In a blend of 3
      Comparative efficacy of probiotic, prebiotic, and synbiotic interventions in children with functional abdominal pain disorders: a systematic review and network meta-analysis. PubMed ↗
    5. Randomized trial Nutrients · 2026 Single strain
      Long-Term Efficacy of Limosilactobacillus reuteri DSM17938 in the Prevention of Functional Abdominal Pain Disorders. PubMed ↗
    6. Systematic review Journal of pediatric gastroenterology and nutrition · 2026 Single strain
      Systematic review: Limosilactobacillus reuteri DSM 17938 for preventing antibiotic-associated diarrhoea in children. PubMed ↗
    7. Randomized trial Nature communications · 2025 Single strain
      A young child formula with Limosilactobacillus reuteri and GOS modulates gut microbiome and enhances bone and muscle development: a randomized trial. PubMed ↗
    8. Randomized trial International dental journal · 2025 Single strain
      Probiotics Enhance Bone Density and Reduce Inflammation Postalveolar Surgery. PubMed ↗
    9. Randomized trial European journal of pediatrics · 2025 Single strain
      Effect of Limosilactobacillus reuteri DSM17938 to prevent antibiotic-associated diarrhea in children: prospective, multi-center, randomized, placebo-controlled clinical trial (PEARL Study). PubMed ↗
    10. Randomized trial Journal of tropical pediatrics · 2025 In a blend of 2
      Efficacy of Lactobacillus reuteri DSM 17938 in Thai children with acute gastroenteritis and normal or mild dehydration in an outpatient setting: a randomized controlled trial. PubMed ↗
    11. Randomized trial International dental journal · 2025 In a blend of 4
      The Probiotic Effects of Lactobacillus brevis CD2 on Caries Related Variables of Dental Plaque Biofilm. PubMed ↗
    12. Randomized trial Journal of pediatric gastroenterology and nutrition · 2025 Single strain
      Lactobacillus reuteri protectis DSM 17938 at high doses versus placebo in children with acute gastroenteritis in a Pediatric Emergency Department. PubMed ↗
    13. Randomized trial Acta paediatrica · 2025 Single strain
      Neurodevelopment and Growth 2 Years After Probiotic Supplementation in Extremely Preterm Infants: A Randomised Trial. PubMed ↗
    14. Randomized trial The American journal of tropical medicine and hygiene · 2025 Single strain
      Effect of Nitazoxanide and Probiotic Treatment on Bangladeshi Children with Cryptosporidiosis. PubMed ↗
    15. Randomized trial PloS one · 2024 In a blend of 2
      The effects of a 6-week intervention with Limosilactobacillus reuteri ATCC PTA 6475 alone and in combination with L. reuteri DSM 17938 on gut barrier function, immune markers, and symptoms in patients with IBS-D-An exploratory RCT. PubMed ↗
    16. Randomized trial Beneficial microbes · 2024 Single strain
      Effects of Limosilactobacillus reuteri DSM 17938 in neonates exposed to antibiotics: a randomised controlled trial. PubMed ↗
    17. Randomized trial The Journal of nutrition · 2024 Single strain
      Iron Absorption from an Iron-Fortified Follow-Up Formula with and without the Addition of a Synbiotic or a Human-Identical Milk Oligosaccharide: A Randomized Crossover Stable Isotope Study in Young Thai Children. PubMed ↗
    18. Randomized trial Cell host & microbe · 2023 Single strain
      Precision microbial intervention improves social behavior but not autism severity: A pilot double-blind randomized placebo-controlled trial. PubMed ↗
    19. Meta-analysis Acta paediatrica · 2023 Single strain
      Probiotics for infantile colic: Is there evidence beyond doubt? A meta-analysis and systematic review. PubMed ↗
    20. Meta-analysis JPEN. Journal of parenteral and enteral nutrition · 2023 Single strain
      Limosilactobacillus reuteri DSM 17938 as a probiotic in preterm infants: An updated systematic review with meta-analysis and trial sequential analysis. PubMed ↗
    21. Randomized trial The American journal of clinical nutrition · 2023 Single strain
      Probiotics for children with uncomplicated severe acute malnutrition (PruSAM study): A randomized controlled trial in the Democratic Republic of Congo. PubMed ↗
    22. Randomized trial Gut microbes · 2023 Single strain
      Limosilactobacillus reuteri DSM 17938 supplementation and SARS-CoV-2 specific antibody response in healthy adults: a randomized, triple-blinded, placebo-controlled trial. PubMed ↗
    23. Systematic review Clinical nutrition · 2022 In a blend of 3
      The use of probiotics and prebiotics can enable the ingestion of dairy products by lactose intolerant individuals. PubMed ↗
    24. Randomized trial BMJ global health · 2022 Single strain
      Optimising the management of childhood acute diarrhoeal disease using a rapid test-and- treat strategy and/or Lactobacillus reuteri DSM 17938: a multicentre, randomised, controlled, factorial trial in Botswana. PubMed ↗
    25. Randomized trial Nutrition journal · 2022 Single strain
      Safety and efficacy of a probiotic-containing infant formula supplemented with 2'-fucosyllactose: a double-blind randomized controlled trial. PubMed ↗
  2. 27 human trials · 1 review 1 single-strain · 26 in blends
  3. L. reuteri ATCC PTA 5289

    In 4 products →
    25 human trials 18 single-strain · 7 in blends
  4. L. reuteri NCIMB 30242

    In 11 products →
    7 human trials · 1 review 7 single-strain · 0 in blends
  5. L. reuteri ATCC PTA 6475

    In 1 product →
    7 human trials 4 single-strain · 3 in blends
  6. L. reuteri SD-5865

    In 17 products →
    1 human trial 1 single-strain · 0 in blends
  7. 18 more strains with no human trials found yet · together in 97 products
    1. L. reuteri UALre-16

      In 28 products →

      No human trials found yet

    2. L. reuteri 1E1

      In 24 products →

      No human trials found yet

    3. L. reuteri LRE02

      In 16 products →

      No human trials found yet

    4. L. reuteri VPLR-1

      In 11 products →

      No human trials found yet

    5. L. reuteri VP-108

      In 10 products →

      No human trials found yet

    6. L. reuteri VP-24

      In 10 products →

      No human trials found yet

    7. L. reuteri HA-188

      In 5 products →

      No human trials found yet

    8. L. reuteri SD-1357

      In 4 products →

      No human trials found yet

    9. L. reuteri E1E

      In 3 products →

      No human trials found yet

    10. L. reuteri HR7

      In 1 product →

      No human trials found yet

    11. L. reuteri LRo8

      In 1 product →

      No human trials found yet

    12. L. reuteri MAK02L14R

      In 1 product →

      No human trials found yet

    13. L. reuteri NI351

      In 1 product →

      No human trials found yet

    14. L. reuteri RD830-FR

      In 1 product →

      No human trials found yet

    15. L. reuteri Rosell 444

      In 1 product →

      No human trials found yet

    16. L. reuteri VP-56

      In 1 product →

      No human trials found yet

    17. L. reuteri VP-66

      In 1 product →

      No human trials found yet

    18. L. reuteri VP-78

      In 1 product →

      No human trials found yet

Human trials, meta-analyses and systematic reviews naming the strain · animal and lab studies not counted · Data sources

On the shelf

Products that contain it

See all 329 →