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Bacteria

Lactobacillus Reuteri

Lactobacillus reuteri, now named Limosilactobacillus reuteri, is a lactic acid bacterium that lives in the gut of humans and animals and also occurs in breast milk.

Also listed as ATCC PTA 6475, ATCC 55730, DSM 17938, NCIMB 30242

Gut HealthImmune SupportHair & SkinLongevity

What it is studied for

The strongest rated effects first. Bars show the size of the effect, the letter grades the evidence, and each rating lists the studies behind it.

Gut healthStrongA3 studies
DiarrheaStrongA3 studies
InflammationModerateA3 studies
Microbiome healthGut HealthModerateA3 studies
Immune SupportModerateA3 studies
Bloating & gas reliefGut HealthModerateBNo linked study
All 10 rated effectsGrouped by health goal, with the publications behind each rating

Which L. reuteri are you considering?

Lactobacillus reuteri is a bacterial species, not a single standardized treatment. The strain code matters: ESPGHAN recommendations discussed here concern DSM 17938. Benefits found for a named probiotic strain cannot simply be transferred to other strains or combinations. ESPGHAN is the European Society for Paediatric Gastroenterology, Hepatology and Nutrition. 1 2

Match the product to the problem

The most useful question is whether a particular strain has improved the symptom you want to address in people like you. Research on infant crying, childhood abdominal pain and acute diarrhea answers different questions; it does not establish a universal daily supplement for digestive health. 1 2

Key studies

The most recent publications linked to Lactobacillus Reuteri's ratings.

Lactobacillus reuteri in digestive system diseases: focus on clinical trials and mechanisms2023Lactobacillus Reuteri DSM 17938 (Limosilactobacillus reuteri) in Diarrhea and Constipation: Two Sides of the Same Coin?2021Effects of Lactobacillus reuteri supplementation on the gut microbiota in extremely preterm infants in a randomized placebo-controlled trial2021Lactobacillus reuteri V3401 Reduces Inflammatory Biomarkers and Modifies the Gastrointestinal Microbiome in Adults with Metabolic Syndrome: The PROSIR Study2019Lactobacillus reuteri for Infants with Colic: A Double‐Blind, Placebo‐Controlled, Randomized Clinical Trial2017
All 12 studiesEvery publication linked to Lactobacillus Reuteri

Why people take it

Gut Health25.3%
Immune Support24.6%
Essential Health21.2%
Women's Hormones7.7%
Detox4.4%
Energy3.4%

SuppCo community snapshot, 2026-09-28. Reasons for use are not evidence that it works.

Questions people ask

Does every L. reuteri product work alike?

No. The DSM 17938 findings apply to that strain and the studied condition; another strain or mixture needs its own evidence. 1 2

Can it help a formula-fed baby with colic?

Evidence is insufficient for a recommendation. The favorable ESPGHAN option is specifically for breastfed infants. 2

How long was it used for colic?

ESPGHAN describes at least 21 days for DSM 17938 in breastfed infants. This is not evidence for indefinite daily use. 2

Will it relieve constipation?

It is not an established treatment for childhood functional constipation; ESPGHAN recommends against probiotics for that purpose. 2

Is a bigger bacterial count better?

The appropriate dose depends on the strain and indication. Match the product to human evidence rather than choosing by the largest number on the bottle. 1

Sources

  1. Probiotics: Health Professional Fact Sheet NIH Office of Dietary Supplements