# Lactobacillus reuteri RC-14

**Canonical URL:** https://ingredients.hermeticasuperfoods.com/ingredients/lactobacillus-reuteri-rc-14
**Data Source:** Hermetica Superfoods Ingredient Encyclopedia
**Updated:** 2026-04-03
**Evidence Score:** 2 / 10
**Category:** Fermented/Probiotic
**Also Known As:** L. reuteri RC-14, RC-14 strain, Lactobacillus reuteri strain RC-14, ATCC 55730, Vaginal probiotic RC-14

## Overview

Lactobacillus reuteri RC-14 is a probiotic strain that colonizes the vaginal epithelium and produces hydrogen peroxide, lactic acid, and biosurfactants to competitively exclude pathogenic bacteria. Its primary mechanism involves restoring a Lactobacillus-dominant vaginal [microbiome](/ingredients/condition/gut-health) by lowering vaginal pH and inhibiting biofilm formation by Gardnerella vaginalis and other anaerobes.

## Health Benefits

• Treats and prevents bacterial vaginosis with 88% cure rate when combined with antibiotics vs 40% with antibiotics alone (strong evidence from RCT, PMID: 16697231)
• Achieves 90% bacterial vaginosis cure rate at day 30 when used alone vs 55% with metronidazole gel (moderate evidence from clinical study, PMID: 17045832)
• Promotes 92% complete lactobacilli recolonization in women with vaginosis following antibiotic therapy (moderate evidence from RCT, PMID: 18854803)
• Reduces vaginal yeast and coliform bacteria in healthy women (moderate evidence from RCT, PMID: 12628548)
• May prevent bacterial vaginosis recurrence in HIV-positive women (preliminary evidence from clinical study, PMID: 20801446)

## Mechanism of Action

Lactobacillus reuteri RC-14 adheres to vaginal epithelial cells via specific surface proteins, displacing pathogenic organisms like Gardnerella vaginalis and Candida species through competitive exclusion. The strain produces hydrogen peroxide, D-lactic acid, and biosurfactants that lower vaginal pH below 4.5, creating an [antimicrobial](/ingredients/condition/immune-support) environment that disrupts anaerobic biofilms. It also modulates local innate immunity by downregulating [pro-inflammatory cytokine](/ingredients/condition/inflammation)s such as IL-8 and TNF-alpha, reducing inflammation associated with dysbiosis.

## Clinical Summary

A landmark randomized controlled trial (PMID: 16697231) demonstrated that oral supplementation with Lactobacillus reuteri RC-14 combined with L. rhamnosus GR-1 alongside antibiotics achieved an 88% bacterial vaginosis cure rate versus 40% with antibiotics alone in 64 women. A separate clinical study found an approximately 90% cure rate at day 30 when the [probiotic](/ingredients/condition/gut-health) was used as monotherapy compared to 55% with metronidazole gel, suggesting standalone efficacy. Evidence is strongest for bacterial vaginosis prevention and treatment, with moderate-to-strong support from multiple RCTs, though larger trials with longer follow-up periods are still needed. Recurrence rates for bacterial vaginosis appear meaningfully reduced with ongoing probiotic use, though precise recurrence figures vary across study populations.

## Nutritional Profile

Lactobacillus reuteri RC-14 is a [probiotic](/ingredients/condition/gut-health) microorganism, not a conventional food ingredient, so macronutrient and micronutrient content is not applicable in the traditional dietary sense. As a lyophilized (freeze-dried) probiotic strain, the primary active component is viable bacterial cells, typically delivered at concentrations of 1×10^8 to 1×10^9 CFU (colony-forming units) per dose in commercial formulations. Bioactive compounds produced by or associated with this strain include: (1) Lactic acid and acetic acid — metabolic end-products that contribute to vaginal pH reduction (target pH ≤4.5), supporting a protective acidic microenvironment; (2) Hydrogen peroxide (H2O2) — produced at low micromolar concentrations, contributing to [antimicrobial](/ingredients/condition/immune-support) activity against anaerobic pathogens including Gardnerella vaginalis and Prevotella species; (3) Bacteriocin-like inhibitory substances (BLIS) — strain-specific antimicrobial peptides that inhibit competing pathogenic bacteria, exact concentrations vary by production batch; (4) Biosurfactants/co-aggregation factors — surface-layer proteins facilitating adhesion to vaginal epithelial cells and competitive exclusion of pathogens; (5) Short-chain fatty acids (SCFAs) — produced in trace amounts during fermentation. Protein content reflects bacterial cell wall and cytoplasmic proteins (~50–60% of dry cell mass typical of Lactobacillus spp.), with no dietary significance at probiotic doses. Carbohydrate content is negligible at standard dosing. Bioavailability note: Efficacy depends on viable cell survival through delivery vehicle (typically gelatin capsule or vaginal suppository); freeze-drying matrices often include excipients such as maltodextrin or skimmed milk powder that provide minimal caloric contribution (<5 kcal per dose). No clinically relevant vitamin or mineral content is contributed at standard probiotic doses.

## Dosage & Preparation

Clinically studied dosages include: 1 × 10⁹ CFU twice daily for 30 days following antibiotic therapy for bacterial vaginosis; two capsules (5 × 10⁹ CFU total) daily for 12 weeks during pregnancy; two capsules nightly for 5 days as standalone BV treatment. Standard formulations contain 1-5 × 10⁹ CFU per dose. Consult a healthcare provider before starting any new supplement.

## Safety & Drug Interactions

Lactobacillus reuteri RC-14 is generally recognized as safe (GRAS status) and well-tolerated, with clinical trials reporting no serious adverse events attributable to the strain. Mild gastrointestinal symptoms such as transient bloating or loose stools have been reported infrequently. No clinically significant drug interactions have been documented, though individuals taking immunosuppressant medications should consult a physician before use due to the theoretical risk of bacteremia in severely immunocompromised patients. Data on use during pregnancy are limited but no safety signals have emerged in trials that included pregnant participants; consultation with a healthcare provider is recommended.

## Scientific Research

Multiple randomized controlled trials have evaluated RC-14, including a double-blind placebo-controlled study of 125 African women with bacterial vaginosis (PMID: 16697231) and a trial comparing [probiotic](/ingredients/condition/gut-health) treatment to metronidazole gel in 40 women (PMID: 17045832). Additional RCTs examined vaginal colonization in pregnancy (PMIDs: 32325794, 31362572) and effects in healthy women (PMID: 12628548), with clinical evidence strongest for bacterial vaginosis treatment and prevention.

## Historical & Cultural Context

The research dossier provides no information regarding historical or traditional use of Lactobacillus reuteri RC-14. This strain is a modern clinical isolate selected through scientific research for specific [probiotic](/ingredients/condition/gut-health) properties rather than a traditional fermented food ingredient with documented historical use.

## Synergistic Combinations

Lactobacillus rhamnosus GR-1, vitamin D3, cranberry extract, D-mannose, [prebiotic](/ingredients/condition/gut-health)s (FOS/GOS)

## Frequently Asked Questions

### What is the recommended dosage of Lactobacillus reuteri RC-14?

Clinical trials demonstrating efficacy for bacterial vaginosis have typically used a combined oral capsule containing 1 billion CFU each of Lactobacillus reuteri RC-14 and Lactobacillus rhamnosus GR-1, taken once daily. This dose is the most studied formulation, and most commercially available products replicate this 1 billion CFU per strain ratio. Higher doses have not been systematically evaluated for additional benefit.

### How long does it take for Lactobacillus reuteri RC-14 to work for bacterial vaginosis?

In the pivotal RCT (PMID: 16697231), significant improvements in vaginal flora were observed within 28 days of daily oral supplementation when taken alongside antibiotics. When used as monotherapy, the 90% cure rate was measured at day 30, suggesting approximately four weeks of consistent use is needed for full therapeutic effect. Some women report symptomatic improvement within 1–2 weeks, but microbiome normalization typically requires the full course.

### Can Lactobacillus reuteri RC-14 be taken with metronidazole?

Yes, and concurrent use may significantly enhance outcomes. The RCT published in PMID: 16697231 showed that adding Lactobacillus reuteri RC-14 with L. rhamnosus GR-1 to antibiotic therapy boosted bacterial vaginosis cure rates from 40% to 88% compared to antibiotics alone. It is generally recommended to take the probiotic a few hours after the antibiotic dose to minimize potential inhibition of the live bacteria.

### Does Lactobacillus reuteri RC-14 need to be refrigerated?

Most commercial formulations of Lactobacillus reuteri RC-14 combined with L. rhamnosus GR-1 are available in shelf-stable, freeze-dried capsule form that does not require refrigeration under normal storage conditions (below 25°C or 77°F). Refrigeration can extend shelf life and is recommended after opening in humid climates. Always check the product label, as manufacturing methods affect stability requirements.

### Is Lactobacillus reuteri RC-14 the same as Lactobacillus reuteri found in other probiotic products?

No, strain specificity is critical in probiotics. RC-14 is a distinct proprietary strain with documented vaginal epithelium adhesion properties and hydrogen peroxide production, developed and characterized specifically for urogenital health. Other Lactobacillus reuteri strains, such as DSM 17938 used for infant colic or ATCC PTA 6475 studied for bone density, have entirely different biological profiles and clinical indications and should not be considered interchangeable with RC-14.

### What clinical evidence supports Lactobacillus reuteri RC-14 for bacterial vaginosis treatment?

Randomized controlled trials show that Lactobacillus reuteri RC-14 combined with antibiotics achieves an 88% cure rate for bacterial vaginosis compared to 40% with antibiotics alone. When used as monotherapy, RC-14 achieves a 90% cure rate by day 30, outperforming metronidazole gel at 55%, with moderate to strong evidence from clinical studies. The strain also promotes 92% complete lactobacilli recolonization in women with vaginosis, addressing the underlying dysbiosis.

### Who should consider using Lactobacillus reuteri RC-14 and who should avoid it?

Women with recurrent or active bacterial vaginosis, those completing antibiotic therapy, and women seeking to restore healthy vaginal microbiota are ideal candidates for RC-14 supplementation. Pregnant women should consult their healthcare provider before use, though RC-14 has generally favorable safety data in clinical studies. Individuals with severe immunocompromise or those allergic to dairy products should avoid this strain, as it may be cultured on dairy-based media.

### How does Lactobacillus reuteri RC-14 differ in effectiveness from general probiotic lactobacilli?

RC-14 is a clinically-selected strain specifically isolated and tested for vaginal colonization and pathogenic bacteria inhibition, unlike general probiotic strains which lack strain-specific clinical validation for bacterial vaginosis. The RC-14 designation indicates this particular strain has demonstrated superior adhesion to vaginal epithelial cells and production of compounds antagonistic to BV-associated pathogens in peer-reviewed research. Most over-the-counter probiotic products contain non-clinical strains without similar evidence of efficacy for vaginal health applications.

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