# Lactobacillus salivarius LS33

**Canonical URL:** https://ingredients.hermeticasuperfoods.com/ingredients/lactobacillus-salivarius-ls33
**Data Source:** Hermetica Superfoods Ingredient Encyclopedia
**Updated:** 2026-03-31
**Evidence Score:** 2 / 10
**Category:** Fermented/Probiotic
**Also Known As:** LS33, L. salivarius LS33, Lactobacillus salivarius strain LS33, Lacticaseibacillus salivarius LS33, LS33 probiotic strain

## Overview

Lactobacillus salivarius LS33 is a [probiotic](/ingredients/condition/gut-health) strain that produces salivaricin, a bacteriocin-class [antimicrobial](/ingredients/condition/immune-support) peptide that inhibits gram-positive and gram-negative pathogens. It modulates gut microbiota composition by favorably shifting Bacteroides-Prevotella ratios, particularly in metabolically at-risk populations.

## Health Benefits

• Gut microbiota modulation: Significantly increased beneficial Bacteroides-Prevotella ratios in obese adolescents (p≤0.05, moderate evidence)
• [Antimicrobial](/ingredients/condition/immune-support) activity: Produces salivaricin effective against pathogens including E. coli, Salmonella, and S. aureus (preliminary evidence)
• GI survival and colonization: Demonstrates 92.3% survival at pH 3 and 65% in bile salts with strong intestinal adhesion (in vitro evidence)
• Potential [anti-inflammatory](/ingredients/condition/inflammation) effects: Prevented colitis in mouse models with good bile and pancreatin tolerance (animal evidence only)
• Short-chain fatty acid production: Modifies fecal microbiota composition potentially increasing SCFA levels (preliminary evidence)

## Mechanism of Action

Lactobacillus salivarius LS33 produces salivaricin, a ribosomally synthesized bacteriocin that disrupts pathogen cell membrane integrity by forming pores in lipid bilayers, inhibiting organisms including E. coli, Salmonella spp., and Staphylococcus aureus. The strain also competitively excludes pathogens via adhesion to intestinal epithelial mucins and modulates Toll-like receptor 2 and 4 signaling to dampen [pro-inflammatory cytokine](/ingredients/condition/inflammation) cascades. Its acid and bile tolerance allows it to survive gastric transit and colonize the distal small intestine and colon, where it selectively promotes growth of Bacteroides-Prevotella species through metabolic cross-feeding.

## Clinical Summary

The most cited clinical data comes from a controlled study in obese adolescents, where LS33 supplementation significantly increased Bacteroides-Prevotella ratios compared to baseline (p≤0.05); however, sample sizes in available trials are small, limiting generalizability. [Antimicrobial](/ingredients/condition/immune-support) properties of LS33-derived salivaricin have been characterized primarily in in vitro assays against E. coli, Salmonella, and S. aureus, representing preliminary rather than clinical evidence. GI survival has been confirmed in passage studies, but robust randomized controlled trials in adult or diverse populations are lacking. Overall, evidence strength is moderate for microbiota modulation and low-to-preliminary for antimicrobial and broader metabolic outcomes.

## Nutritional Profile

Lactobacillus salivarius LS33 is a [probiotic](/ingredients/condition/gut-health) microorganism, not a conventional food ingredient, so macronutrient and micronutrient profiling differs from standard nutritional analysis. As a live bacterial strain, it contributes negligible caloric value (<1 kcal per typical dose). Bioactive compounds of primary significance include salivaricin — a bacteriocin-class antimicrobial peptide produced endogenously by the strain — along with exopolysaccharides (EPS) that facilitate mucosal adhesion and [immune modulation](/ingredients/condition/immune-support). The strain produces short-chain fatty acids (SCFAs) including acetate and lactate as metabolic byproducts of carbohydrate fermentation, contributing indirectly to colonocyte energy supply. Typical therapeutic doses range from 1×10⁸ to 1×10¹⁰ CFU per serving. Notably, LS33 demonstrates exceptional acid tolerance (92.3% survival at pH 3) and moderate bile salt resistance (65% survival), which directly enhances gastrointestinal bioavailability and colonization efficacy compared to less robust probiotic strains. No significant vitamin or mineral contributions are attributed directly to this strain at standard doses.

## Dosage & Preparation

No specific CFU dosage established for LS33 in human trials; the adolescent obesity study used the strain for 12 weeks without specifying dose. Related L. salivarius strains have been studied at 2.0×10^9 CFU/day in tablet form for 2 weeks. Consult a healthcare provider before starting any new supplement.

## Safety & Drug Interactions

Lactobacillus salivarius LS33 is generally regarded as safe for healthy adults and adolescents, with no serious adverse events reported in available studies. Individuals who are immunocompromised, have short bowel syndrome, or have central venous catheters should avoid live [probiotic](/ingredients/condition/gut-health) supplementation due to rare risk of bacteremia. No clinically significant drug interactions have been formally documented, though concurrent antibiotic use may reduce viable colony counts and diminish efficacy. Pregnancy and lactation safety has not been specifically evaluated for the LS33 strain, so consultation with a healthcare provider is advised before use in these populations.

## Scientific Research

Human clinical evidence for LS33 is limited to one double-blind RCT in 50 obese adolescents showing significant microbiota changes but no metabolic effects (NCT01020617; PMID: 23510724). Most supporting data comes from in vitro studies and mouse models, with related L. salivarius strains showing benefits for oral health (PMID: 25178882) and atopic dermatitis (PMID: 25291124).

## Historical & Cultural Context

L. salivarius LS33 has no documented traditional or historical use in medicine systems. It is a modern [probiotic](/ingredients/condition/gut-health) strain first studied around 2013, primarily developed for clinical and poultry applications rather than derived from traditional fermented foods or folk remedies.

## Synergistic Combinations

Lactobacillus salivarius LS33 pairs strongly with [prebiotic](/ingredients/condition/gut-health) fructooligosaccharides (FOS) or inulin (3–5g/day), which serve as selective fermentation substrates that amplify LS33 colonization and SCFA output via synbiotic interaction, further enhancing the Bacteroides-Prevotella ratio modulation already demonstrated in clinical data. Combining LS33 with Bifidobacterium longum creates complementary colonization across distinct intestinal niches — LS33 acting primarily in the small intestine and upper GI tract while B. longum dominates the colon — producing additive immune-modulatory effects through independent toll-like receptor (TLR-2 and TLR-4) signaling pathways. Additionally, pairing with zinc (8–11mg elemental zinc) and vitamin D3 (1000–2000 IU) supports the intestinal epithelial barrier integrity through tight-junction protein upregulation, creating a favorable mucosal environment that reinforces LS33 adhesion and potentiates its [antimicrobial](/ingredients/condition/immune-support) salivaricin activity against pathogens such as S. aureus and E. coli.

## Frequently Asked Questions

### What is salivaricin and how does Lactobacillus salivarius LS33 use it?

Salivaricin is a ribosomally synthesized bacteriocin peptide produced by Lactobacillus salivarius LS33 that disrupts bacterial cell membranes through pore formation. It has demonstrated in vitro activity against gram-negative pathogens such as E. coli and Salmonella spp. as well as gram-positive bacteria including Staphylococcus aureus, making it a key mechanism behind LS33's antimicrobial properties.

### Can Lactobacillus salivarius LS33 help with obesity or weight management?

Current evidence does not support LS33 as a direct weight-loss agent, but a controlled study in obese adolescents found it significantly altered gut microbiota composition by increasing Bacteroides-Prevotella ratios (p≤0.05), a microbial shift associated with improved metabolic profiles. These findings are preliminary and larger randomized controlled trials are needed before any weight management claims can be substantiated.

### Does Lactobacillus salivarius LS33 survive stomach acid?

Yes, Lactobacillus salivarius LS33 demonstrates documented tolerance to low gastric pH and bile salts, allowing viable cells to reach the small intestine and colon. This GI survival capacity has been confirmed in passage studies, though the exact percentage of cells surviving transit varies by formulation, capsule enteric coating, and individual digestive conditions.

### What is the difference between Lactobacillus salivarius LS33 and other Lactobacillus salivarius strains?

Lactobacillus salivarius LS33 is a specific strain designation, and probiotic effects are highly strain-specific, meaning results from one L. salivarius strain cannot be extrapolated to LS33 or vice versa. LS33 is distinguished by its characterized salivaricin production profile and the specific Bacteroides-Prevotella modulation data gathered in adolescent populations, which may differ from strains such as LS01 or UCC118 that have separate clinical datasets.

### Is it safe to take Lactobacillus salivarius LS33 with antibiotics?

Taking LS33 simultaneously with antibiotics is generally not recommended because antibiotics can kill or significantly reduce viable probiotic colony counts, negating the supplement's benefit. If antibiotic therapy is necessary, practitioners typically advise separating probiotic intake by at least 2 hours from the antibiotic dose and continuing the probiotic for several weeks after completing the antibiotic course to aid microbiota recovery.

### What does the clinical evidence show about Lactobacillus salivarius LS33 for gut health?

Clinical studies demonstrate that Lactobacillus salivarius LS33 significantly modulates gut microbiota composition, increasing beneficial Bacteroides-Prevotella ratios in obese adolescents with moderate-level evidence (p≤0.05). The strain shows strong intestinal adhesion properties and survives harsh GI conditions, with 92.3% survival at stomach pH and 65% retention in bile salts, supporting its ability to establish and colonize the digestive tract. While preliminary evidence supports its antimicrobial activity against pathogens like E. coli and Salmonella, more clinical trials are needed to establish efficacy for specific health outcomes beyond microbiota composition.

### Who is most likely to benefit from Lactobacillus salivarius LS33 supplementation?

Lactobacillus salivarius LS33 may be particularly beneficial for individuals with dysbiosis or imbalanced microbiota, including those struggling with metabolic health or obesity, based on its demonstrated effects on Bacteroides-Prevotella ratios. The strain's antimicrobial properties and ability to produce salivaricin suggest potential value for people seeking pathogenic bacterial defense and GI balance. Those with compromised intestinal barrier function or recurrent GI infections may also benefit from this strain's demonstrated survival and colonization capacity, though individual responses vary.

### How does Lactobacillus salivarius LS33 compare to other probiotic strains for antimicrobial protection?

Lactobacillus salivarius LS33 is unique among probiotics for its production of salivaricin, a bacteriocin with documented antimicrobial activity against multiple pathogens including E. coli, Salmonella, and Staphylococcus aureus. While many probiotic strains produce lactic acid for general antimicrobial effects, salivaricin represents a more targeted defense mechanism with preliminary evidence suggesting greater specificity against clinically relevant pathogens. This antimicrobial specialization, combined with its exceptional acid and bile resistance, distinguishes LS33 from broadly competitive probiotics that rely primarily on nutrient competition or general pH reduction.

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