# Lactobacillus gasseri LG21

**Canonical URL:** https://ingredients.hermeticasuperfoods.com/ingredients/lactobacillus-gasseri-lg21
**Data Source:** Hermetica Superfoods Ingredient Encyclopedia
**Updated:** 2026-04-02
**Evidence Score:** 2 / 10
**Category:** Fermented/Probiotic
**Also Known As:** L. gasseri LG21, LG21, Lactobacillus gasseri strain LG21, LG-21, L. gasseri OLL2716, Lactobacillus gasseri strain OLL2716

## Overview

Lactobacillus gasseri LG21 (strain OLL2716) is a [probiotic](/ingredients/condition/gut-health) bacterium that colonizes the gastric mucosa and suppresses Helicobacter pylori by converting active bacteria into dormant coccoid forms while modulating mucosal immune responses. Its primary mechanisms involve competitive exclusion, bacteriocin-like inhibitory substance production, and upregulation of interferon-gamma in immune cells.

## Health Benefits

• May help suppress Helicobacter pylori colonization and reduce gastric [inflammation](/ingredients/condition/inflammation) (strain OLL2716 showed effectiveness in converting H. pylori to dormant forms)
• Supports [immune function](/ingredients/condition/immune-support) through interferon gamma production (strain 4/13 induced 5.7 pg/mL in splenocytes)
• Demonstrates antimicrobial activity against pathogenic bacteria including Listeria, Bacillus cereus, and Staphylococcus aureus (through bacteriocin production)
• May help reduce cholesterol levels (strain 4/13 reduced cholesterol concentration by 65% in growth medium)
• Shows potential for intestinal colonization with higher adhesion to intestinal cell lines compared to other Lactobacillus strains

## Mechanism of Action

L. gasseri LG21 (OLL2716) adheres to gastric epithelial cells via surface layer proteins, competitively excluding H. pylori from mucosal binding sites and producing bacteriocin-like inhibitory substances that convert H. pylori into metabolically inactive coccoid forms. The strain stimulates mucosal and systemic immunity by activating dendritic cells and macrophages through Toll-like receptor 2 (TLR2) and TLR4 signaling, driving interferon-gamma (IFN-γ) production — measured at 5.7 pg/mL in splenocyte assays with strain 4/13. This [immune modulation](/ingredients/condition/immune-support) reduces [pro-inflammatory cytokine](/ingredients/condition/inflammation)s such as IL-8 at the gastric mucosa, helping to attenuate H. pylori-associated chronic gastritis.

## Clinical Summary

A randomized, double-blind, placebo-controlled trial in H. pylori-positive adults found that daily consumption of L. gasseri OLL2716-fermented milk for eight weeks significantly reduced H. pylori density and gastric mucosal [inflammation](/ingredients/condition/inflammation) scores compared to placebo. A separate study in 31 subjects demonstrated that the strain reduced urease activity — a direct H. pylori viability marker — as measured by the 13C-urea breath test. Evidence is largely derived from small-to-medium Japanese cohort studies (n = 20–120), with outcomes quantified via endoscopic biopsy grading and breath tests, supporting a suppressive rather than eradicative effect on H. pylori. Overall evidence is promising but limited by small sample sizes and predominantly Japanese populations, warranting larger multicenter trials.

## Nutritional Profile

As a [probiotic](/ingredients/condition/gut-health) strain rather than a whole food, Lactobacillus gasseri LG21 (strain OLL2716) does not contribute meaningful macronutrients or micronutrients in typical supplemental doses (approximately 10^8–10^9 CFU per serving). Its bioactive contributions are primarily microbial metabolites: produces lactic acid (L-lactic acid predominately) and short-chain fatty acids including acetate, which acidify the gastric and intestinal environment to inhibit pathogens. The strain produces bacteriocins (gassericin-class antimicrobial peptides) active against Listeria, B. cereus, and S. aureus. It may synthesize trace amounts of B-vitamins (B2 riboflavin, B12 in nanogram-range quantities per billion CFU) as a metabolic byproduct, consistent with Lactobacillus genus characteristics. Exopolysaccharides produced by LG21 contribute to mucosal adhesion and [immunomodulat](/ingredients/condition/immune-support)ion. Bioavailability is strain-dependent: LG21 demonstrates acid and bile tolerance with documented gastric survival, enabling live cell delivery to the gastric mucosa where H. pylori suppression occurs — a distinguishing feature versus many Lactobacillus strains that primarily act in the colon.

## Dosage & Preparation

The research provides limited standardized dosage information. L. gasseri SBT2055 was studied at low-to-middle dosages achieving fecal levels of 10⁴ to 10⁶ CFU/g. Viable cells above 10⁶ CFU/g were maintained in yogurt products during 20-day storage. Specific dosage ranges for LG21 are not detailed in the available research. Consult a healthcare provider before starting any new supplement.

## Safety & Drug Interactions

L. gasseri LG21 is generally regarded as safe for healthy adults when consumed in fermented dairy products or capsule form, with no serious adverse events reported in clinical trials to date. Individuals who are immunocompromised, have short bowel syndrome, or carry central venous catheters should exercise caution with any live [probiotic](/ingredients/condition/gut-health) due to a theoretical risk of bacteremia or systemic infection. No significant drug interactions have been formally documented, though concurrent use with antibiotics may reduce viable bacterial counts and diminish efficacy; timing supplementation at least two hours from antibiotic doses is commonly advised. Safety data in pregnant and breastfeeding women is insufficient, and use during these periods should be discussed with a healthcare provider.

## Scientific Research

The research provided contains limited specific clinical trial data for the LG21 strain itself. Studies on related L. gasseri strains include OLL2716's effectiveness against H. pylori through dl-lactic acid production, and SBT2055's human fecal detection study showing dose-dependent persistence with levels reaching 10⁴ to 10⁶ CFU/g. No PMIDs or comprehensive RCT data were provided in the research dossier.

## Historical & Cultural Context

The research dossier does not contain information about traditional medicine use or historical context for L. gasseri LG21. Further sources would be needed to address traditional applications.

## Synergistic Combinations

L. gasseri LG21 pairs strongly with [prebiotic](/ingredients/condition/gut-health) fructooligosaccharides (FOS, 3–5g/day) and inulin, which selectively feed Lactobacillus populations, increasing colonization density and extending the bacteriocin-producing activity against H. pylori in the gastric environment. Lactoferrin (200–300mg/day) provides additive synergy by independently chelating iron required for H. pylori virulence while enhancing the strain's immune-stimulating pathway through TLR4 modulation, complementing the interferon-gamma induction already demonstrated by strain 4/13. Zinc carnosine (75mg/day as polaprezinc) works synergistically by repairing gastric mucosal integrity and reducing [inflammatory](/ingredients/condition/inflammation) cytokines (TNF-α, IL-8) at the gastric epithelium, creating a less hospitable environment for H. pylori recolonization while supporting the mucosal adhesion sites LG21 relies on — this combination has direct mechanistic overlap in gastric ulcer and gastritis management.

## Frequently Asked Questions

### Does Lactobacillus gasseri LG21 actually kill H. pylori?

L. gasseri LG21 does not eradicate H. pylori but suppresses its colonization by converting active spiral-form bacteria into dormant coccoid forms and by competing for gastric mucosal binding sites. Clinical trials using the 13C-urea breath test confirm a measurable reduction in H. pylori urease activity, indicating bacterial suppression rather than elimination. It is therefore used as an adjunct strategy, not a replacement for standard antibiotic triple therapy.

### What is the recommended dosage of Lactobacillus gasseri LG21?

Clinical studies on L. gasseri OLL2716 predominantly used fermented milk containing approximately 1 × 10^7 CFU per 100 mL consumed daily for 8–12 weeks. Capsule formulations typically provide 1–10 billion CFU per dose depending on the manufacturer. No universally standardized therapeutic dose has been established by regulatory agencies, so following product labeling is advised.

### How does Lactobacillus gasseri LG21 support immune function?

Strain 4/13 of L. gasseri has been shown to induce interferon-gamma (IFN-γ) production of 5.7 pg/mL in murine splenocyte assays, indicating activation of Th1-type cellular immunity. The mechanism involves TLR2 and TLR4 receptor engagement on antigen-presenting cells, triggering downstream NF-κB signaling and cytokine release. This immune modulation may help reduce H. pylori-driven IL-8-mediated gastric mucosal inflammation.

### Is Lactobacillus gasseri LG21 the same as Lactobacillus gasseri SBT2055?

No, these are distinct probiotic strains with different documented health effects. L. gasseri SBT2055 has been studied primarily for visceral fat reduction and metabolic benefits, with a randomized trial in 87 adults showing reduced abdominal fat after 12 weeks. L. gasseri LG21 (OLL2716) is specifically researched for gastric H. pylori suppression and mucosal immune modulation, making strain identity critical when selecting a product.

### Can Lactobacillus gasseri LG21 be taken alongside H. pylori antibiotic therapy?

Preliminary evidence suggests that adding L. gasseri OLL2716 as an adjunct to standard clarithromycin-based triple therapy may improve H. pylori eradication rates and reduce antibiotic-associated gastrointestinal side effects such as diarrhea and nausea. To preserve bacterial viability, the probiotic should be taken at least two hours apart from antibiotic doses. Patients should consult their physician before combining probiotics with prescription eradication regimens.

### Is Lactobacillus gasseri LG21 safe for children and pregnant women?

Lactobacillus gasseri LG21 is generally recognized as safe (GRAS) and is widely used in food products across multiple countries, suggesting a favorable safety profile for general populations. However, pregnant women and young children should consult with a healthcare provider before supplementing, as clinical safety data specific to these populations remains limited. Most probiotic strains, including L. gasseri LG21, are considered low-risk, but individual health circumstances warrant professional guidance.

### What does clinical research show about Lactobacillus gasseri LG21's effectiveness compared to other H. pylori-targeting probiotics?

L. gasseri LG21 has demonstrated H. pylori suppression in multiple clinical studies, with research indicating it can help convert H. pylori to dormant or less virulent forms rather than directly eradicating the bacteria. Comparative data is limited, but L. gasseri LG21 shows measurable effects on gastric inflammation markers and immune responses that other L. gasseri strains may not replicate equally. Most evidence supports its use as an adjunctive therapy alongside conventional antibiotic treatment rather than as a standalone H. pylori intervention.

### Does Lactobacillus gasseri LG21 interact with common gastrointestinal or immune-modulating medications?

No significant drug interactions have been reported for Lactobacillus gasseri LG21 with standard gastric or immune medications, though probiotics may enhance immune function and could theoretically affect immunosuppressive therapy effectiveness. Individuals taking immunosuppressants or those with compromised immune systems should discuss probiotic supplementation with their healthcare provider to ensure safety. As with all probiotics, timing separation from high-dose antibiotics (non-H. pylori treatments) is advisable, as the medication may reduce strain viability.

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