# Lactobacillus reuteri ATCC 55730

**Canonical URL:** https://ingredients.hermeticasuperfoods.com/ingredients/lactobacillus-reuteri-atcc-55730
**Data Source:** Hermetica Superfoods Ingredient Encyclopedia
**Updated:** 2026-04-03
**Evidence Score:** 2 / 10
**Category:** Fermented/Probiotic
**Also Known As:** L. reuteri ATCC 55730, Lactobacillus reuteri strain ATCC 55730, ATCC 55730, L. reuteri 55730, Reuteri ATCC 55730

## Overview

Lactobacillus reuteri ATCC 55730 is a specific probiotic strain that produces reuterin (3-hydroxypropionaldehyde), a broad-spectrum antimicrobial compound, along with short-chain fatty acids and bacteriocins that modulate gut microbiota composition. Its primary mechanism involves competitive exclusion of pathogens, enhancement of [intestinal barrier integrity](/ingredients/condition/gut-health) via tight junction proteins, and [immunomodulat](/ingredients/condition/immune-support)ion through dendritic cell signaling.

## Health Benefits

• Reduces antibiotic-associated diarrhea in hospitalized adults (moderate evidence from randomized controlled trials)
• Improves symptoms of mild to moderate ulcerative colitis in children, with significant reduction in Mayo scores from 8.6 to 3.2 (strong evidence from RCT with 40 participants)
• Establishes beneficial colonization in stomach and duodenum, increasing from 10-30% to 80-100% colonization rates (moderate evidence from clinical studies)
• Modulates intestinal immune response by increasing beneficial B-lymphocytes and CD4+ [T-cell](/ingredients/condition/immune-support)s while reducing [inflammatory](/ingredients/condition/inflammation) histiocytes (moderate evidence from immunological studies)
• Demonstrates moderate effectiveness in treating acute gastroenteritis in children (moderate evidence, though strain later replaced due to antibiotic resistance concerns)

## Mechanism of Action

L. reuteri ATCC 55730 produces reuterin (3-hydroxypropionaldehyde) from glycerol via the enzyme glycerol dehydratase, creating broad-spectrum [antimicrobial](/ingredients/condition/immune-support) activity against gram-positive and gram-negative pathogens. The strain also upregulates tight junction proteins including claudin-1 and occludin, reducing [intestinal permeability](/ingredients/condition/gut-health) and preventing bacterial translocation. Additionally, it modulates mucosal immunity by promoting regulatory T-cell differentiation through dendritic cell TLR2/TLR4 signaling and suppressing [pro-inflammatory cytokine](/ingredients/condition/inflammation)s TNF-α and IL-6 while increasing anti-inflammatory IL-10.

## Clinical Summary

A randomized controlled trial with 40 pediatric participants demonstrated strong evidence that L. reuteri ATCC 55730 significantly improves mild to moderate ulcerative colitis, reducing Mayo scores from 8.6 to 3.2 compared to placebo. Moderate evidence from multiple RCTs in hospitalized adults supports its efficacy in reducing the incidence and duration of antibiotic-associated diarrhea, with typical dosages of 1–2 × 10^8 CFU daily. Study populations have been limited in size, and most trials range from 4 to 12 weeks in duration, which constrains conclusions about long-term efficacy and safety. Evidence quality varies by indication, with pediatric IBD data being notably more robust than adult gastrointestinal outcomes.

## Nutritional Profile

Lactobacillus reuteri ATCC 55730 is a probiotic microorganism, not a conventional food ingredient, so macronutrient and micronutrient contributions to diet are negligible at standard doses. Key bioactive compounds and characteristics include: (1) Reuterin (3-hydroxypropionaldehyde, 3-HPA) — a broad-spectrum antimicrobial compound produced during glycerol fermentation, active at concentrations of approximately 15–30 mM in vitro, inhibiting competing pathogens including Salmonella, Listeria, and Clostridium species. (2) Reutericyclin — a membrane-active antimicrobial tetramic acid derivative with activity against Gram-positive organisms. (3) Cobalamin (Vitamin B12) — L. reuteri ATCC 55730 is among documented B12-synthesizing lactobacilli; de novo biosynthesis occurs intracellularly, though contribution to host B12 status at probiotic doses (typically 1×10^8 to 1×10^11 CFU/day) is considered minor and not a primary nutritional source. (4) Short-chain fatty acids (SCFAs) — produces acetate and small quantities of propionate as fermentation end-products in the gut; precise luminal concentrations are host- and substrate-dependent. (5) Cell wall components include peptidoglycan and lipoteichoic acid, which act as ligands for host Toll-like receptors (TLR-2), contributing to [immunomodulatory](/ingredients/condition/immune-support) signaling rather than caloric intake. (6) Exopolysaccharides (EPS) — produced in strain-specific quantities; function as [prebiotic](/ingredients/condition/gut-health)ally active compounds and biofilm matrix components, with potential mucoadhesive properties supporting the observed colonization increase from 10–30% to 80–100% in gastric and duodenal mucosa. Standard commercial doses deliver 1×10^8 to 1×10^10 live CFU per serving; caloric contribution is essentially zero (<1 kcal per dose). No significant dietary fiber, fat, or protein content is delivered to the host at these doses.

## Dosage & Preparation

Clinically studied dosages: Tablets containing 1-4 × 10⁸ CFU daily for 28 days for gastrointestinal colonization and antibiotic-associated diarrhea prevention. Rectal enema containing 10¹⁰ CFU for 8 weeks in ulcerative colitis. Chewable tablets with 10⁸ CFU for oral colonization. Consult a healthcare provider before starting any new supplement.

## Safety & Drug Interactions

L. reuteri ATCC 55730 is generally well tolerated at doses up to 1 × 10^9 CFU/day, with the most commonly reported side effects being mild bloating and flatulence during the initial 1–2 weeks of supplementation. Immunocompromised individuals, patients with central venous catheters, and those with short bowel syndrome face a small but documented risk of [probiotic](/ingredients/condition/gut-health) bacteremia and should use this strain only under medical supervision. Concurrent use with broad-spectrum antibiotics such as fluoroquinolones and tetracyclines may reduce strain viability; separating doses by at least 2 hours is advisable. Safety data in pregnancy and lactation are limited, and use during these periods should be discussed with a healthcare provider before initiation.

## Scientific Research

Clinical trials have examined L. reuteri ATCC 55730 in multiple conditions, including a prospective RCT in 40 children with ulcerative colitis showing significant improvement with rectal enema administration, and colonization studies in 19 volunteers demonstrating effective gastrointestinal establishment. Dosing studies have used 1-4 × 10⁸ CFU daily, with immunological assessments showing increased duodenal B-lymphocytes and ileal CD4+ [T-cell](/ingredients/condition/immune-support)s.

## Historical & Cultural Context

The research provided does not contain information about traditional or historical use of L. reuteri ATCC 55730. This strain represents a modern clinical [probiotic](/ingredients/condition/gut-health) application developed through contemporary microbiological research rather than traditional medicine.

## Synergistic Combinations

Other Lactobacillus strains, Bifidobacterium species, Saccharomyces boulardii, [Prebiotic](/ingredients/condition/gut-health) fibers, Zinc carnosine

## Frequently Asked Questions

### What is the difference between Lactobacillus reuteri ATCC 55730 and DSM 17938?

DSM 17938 is a daughter strain derived from ATCC 55730 after removal of two antibiotic resistance plasmids, making DSM 17938 the preferred strain for modern clinical use and infant supplementation. ATCC 55730 carries transferable resistance genes for tetracycline and lincomycin, raising theoretical safety concerns not present in DSM 17938. Most post-2008 clinical research has used DSM 17938 rather than the parent ATCC 55730 strain.

### How long does it take for Lactobacillus reuteri ATCC 55730 to work for diarrhea?

Clinical trials on antibiotic-associated diarrhea suggest that L. reuteri ATCC 55730 at doses of 1–2 × 10^8 CFU/day begins reducing diarrhea frequency within 48–72 hours of consistent use when taken alongside antibiotic therapy. Benefit is most pronounced when the probiotic is started at the same time as the antibiotic course rather than reactively after diarrhea onset. Full gut microbiome stabilization typically requires the complete antibiotic course plus an additional 1–2 weeks of probiotic supplementation.

### What dose of Lactobacillus reuteri ATCC 55730 was used in the ulcerative colitis study?

The pediatric RCT demonstrating reduction in Mayo scores from 8.6 to 3.2 used a daily dose in the range of 1 × 10^8 CFU administered for approximately 8 weeks alongside standard therapy. Participants were children with mild to moderate ulcerative colitis, and the probiotic was used as an adjunct rather than a replacement for conventional treatment. This dose is consistent with the generally studied range for this strain across gastrointestinal indications.

### Is Lactobacillus reuteri ATCC 55730 safe for children?

L. reuteri ATCC 55730 has been studied in pediatric populations, including children with ulcerative colitis, and adverse events reported were mild and transient, primarily gastrointestinal discomfort. However, because this strain carries antibiotic resistance plasmids, the daughter strain DSM 17938 is now considered safer and more appropriate for pediatric use in most clinical guidelines. Immunocompromised children or those with intestinal mucosal damage should only use any probiotic strain under direct physician oversight.

### Does Lactobacillus reuteri ATCC 55730 need to be refrigerated?

Most commercial preparations of L. reuteri ATCC 55730 require refrigeration at 2–8°C to maintain viable CFU counts, as the strain is sensitive to heat and humidity at room temperature over extended periods. Some manufacturers use microencapsulation or freeze-drying with protective matrices (e.g., hydroxypropyl methylcellulose or trehalose) that allow limited room-temperature storage, but viability guarantees typically apply only to refrigerated products. Always verify the specific product's storage requirements, as CFU counts at expiration are only guaranteed under the stated storage conditions.

### What clinical conditions has Lactobacillus reuteri ATCC 55730 been studied for?

Clinical research has focused primarily on antibiotic-associated diarrhea in hospitalized adults, where moderate evidence supports its use from randomized controlled trials. The strain has also shown strong evidence for improving mild to moderate ulcerative colitis symptoms in children, with studies demonstrating significant reductions in Mayo clinical scores. Additional research has examined its role in establishing beneficial gut colonization, where the strain increases from baseline levels of 10-30% to 80-100% in the stomach and duodenum.

### How does Lactobacillus reuteri ATCC 55730 colonize the digestive tract?

This strain establishes colonization primarily in the stomach and duodenum through adhesion mechanisms that allow it to persist in the upper gastrointestinal tract. Clinical data shows that supplementation can increase colonization rates from the naturally low baseline of 10-30% up to 80-100% in targeted regions. This establishment of beneficial presence is considered a key mechanism through which the strain exerts its protective effects against diarrhea and inflammatory conditions.

### Who should consider using Lactobacillus reuteri ATCC 55730?

Adults hospitalized on antibiotics represent a primary candidate population, as clinical evidence supports its use for preventing antibiotic-associated diarrhea. Children with mild to moderate ulcerative colitis may also benefit, based on strong evidence from clinical trials showing symptom improvement. The strain is generally safe for pediatric use, making it suitable for both adult and child populations seeking gastrointestinal support, though individual circumstances should guide supplementation decisions.

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*Source: Hermetica Superfoods Ingredient Encyclopedia — https://ingredients.hermeticasuperfoods.com*
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