Lactobacillus plantarum | Supplementopedia

Overview

Lactobacillus plantarum is a Gram-positive, facultatively anaerobic, rod-shaped lactic-acid bacterium. It naturally inhabits fermented foods, the human gastrointestinal tract, and various plant surfaces. In dietary supplements, it functions as a probiotic to modulate gut microbiota, improve barrier function, and support systemic health.

Benefits

Gut health & barrier integrity: Randomized trials show L. plantarum (10⁹–10¹¹ CFU/day) reduces abdominal pain, bloating, and stool frequency in irritable-bowel syndrome (IBS) and protects against pathogen-induced diarrhoea.
Metabolic regulation: Meta-analyses report modest reductions in fasting glucose (≈0.3 mmol/L) and LDL-cholesterol (≈5 mg/dL) after 4–12 weeks of supplementation, likely via bile-acid deconjugation and short-chain-fatty-acid (SCFA) production.
Immune modulation: Clinical trials in healthy adults report increased secretory IgA and reduced pro-inflammatory cytokines (IL-6, TNF-α) after 8 weeks, indicating enhanced mucosal immunity.
Cognitive & mood effects: Small RCTs in young adults report improved working-memory scores and lower perceived stress after 6 weeks, suggesting gut-brain axis engagement through tryptophan metabolism.
Antioxidant & anti-inflammatory: In vitro and animal studies demonstrate up-regulation of Nrf2-dependent antioxidant enzymes (e.g., HO-1) and inhibition of NF-κB signaling, supporting systemic anti-oxidative capacity.

How It Works

Colonization and Adhesion: L. plantarum colonizes the distal small intestine and colon, adhering to mucosal epithelia via surface proteins (e.g., mucus-binding protein, Msp) and exopolysaccharides (EPS). This adhesion competitively excludes pathogenic bacteria and stabilizes the mucous layer.
SCFA Production: The bacterium ferments carbohydrates to produce lactate, acetate, and other SCFAs that lower luminal pH, suppress pathogens, and serve as energy substrates for colonocytes.
G-protein Activation: SCFAs activate G-protein-coupled receptors (GPR41/43) on entero-endocrine cells, stimulating GLP-1 and PYY secretion, thereby improving glucose homeostasis and satiety.
Bile Acid Deconjugation: L. plantarum expresses bile-salt hydrolase, deconjugating bile acids to reduce cholesterol absorption.
Immune Modulation: Its cell-wall peptidoglycan and lipoteichoic acid engage pattern-recognition receptors (TLR2, NOD2), leading to a balanced immune response: increased regulatory T-cells, enhanced IgA production, and down-regulation of NF-κB-mediated pro-inflammatory cytokines.

Dosage

Typical Dosage: Clinical studies most commonly use 10⁹–10¹¹ colony-forming units (CFU) per day of a single strain (e.g., L. plantarum NCIMB 8826, ATCC 14917) for 4–12 weeks.
Acute Diarrhea/Post-Antibiotic: For acute diarrhoea or post-antibiotic restoration, 10¹⁰ CFU taken 1–2 times daily is typical.
Chronic Support: For chronic metabolic or immune support, 10⁹–10¹⁰ CFU once daily suffices.
Administration: Capsules should be taken with food to enhance survival through gastric acidity; some formulations use enteric coating for maximal colon-site delivery.
Athletes/Stressed Individuals: In athletes or stressed individuals, 2–3 doses per day (spread across meals) may optimize gut-brain signaling.
Adjustments: Adjustments are advised for pediatric (10⁸–10⁹ CFU) and elderly (10⁹–10¹⁰ CFU) groups based on body weight and microbiome status.

Safety & Side Effects

General Safety: L. plantarum is Generally Recognised As Safe (GRAS) and has a long record of use in fermented foods.
Common Side Effects: Mild, transient gastrointestinal symptoms (bloating, flatulence) are the most common side-effects, typically resolving within 2–3 days.
Contraindications:
- Immunocompromised patients (e.g., chemotherapy, HIV/AIDS)
- Those with central-line catheters or severe mucosal injury
- Infants < 3 months
Rare Risks: Rare case reports of bacteremia exist, primarily in critically ill patients, underscoring the need for medical supervision in high-risk populations.
Drug Interactions: No clinically relevant drug-interactions have been reported, but probiotic use may augment the efficacy of oral vaccines and could theoretically affect immunosuppressant dosing; clinicians should monitor such patients.

Chemistry

Bacterial Composition: Lactobacillus plantarum is a living bacterium; its “chemical structure” is defined by its genome (≈3.3 Mbp, ~3,200 genes) and cell-wall components.
Peptidoglycan: The peptidoglycan backbone comprises N-acetyl-glucosamine–N-acetyl-muramic acid polymers cross-linked by L-lysine-type peptide bridges (L-Ala-L-Ala).
Lipoteichoic Acids: Lipoteichoic acids (glycerol-phosphate polymers with glycolipid anchors) and surface-exposed proteins (Msp, adhesion factors) define its interaction surface.
Lactic Acid Production: The organism produces lactic acid (C₃H₆O₃) as its primary metabolite; the molecular formula of lactic acid is C₃H₆O₃ (IUPAC: 2-hydroxypropanoic acid).
Extracellular Polysaccharides (EPS): Extracellular polysaccharides (EPS) consist of glucose, galactose, and rhamnose units linked via β-1,4/β-1,3 glycosidic bonds, contributing to its viscosity and immune-modulatory properties.

Sources & Quality

Source: Commercial L. plantarum is harvested from traditional fermented foods (e.g., kimchi, sauerkraut, sourdough) or isolated from human fecal samples under strict anaerobic conditions.
Strain Selection: Strains are selected for stability, acid and bile tolerance, and documented health effects.
Production: Production involves a two-stage fermentation: (i) seed-culture in MRS broth, followed by (ii) large-scale fermentation in bioreactors (pH 6.2, 37 °C, anaerobic).
Processing: Harvested cells are concentrated, washed, and lyophilised with cryoprotectants (e.g., trehalose) to preserve viability.
Quality Control: Good Manufacturing Practice (GMP) facilities ensure ≥90 % viability at the end of shelf-life. Quality control includes strain verification by 16S rRNA sequencing, CFU enumeration, and absence of pathogens (e.g., E. coli, Salmonella).
Quality Markers: Certified organic or non-GMO certification, as well as third-party testing for potency and contaminants, are key quality markers for consumers.