Fermented cabbage preserved intestinal barrier integrity in vitro by preventing cytokine-induced permeability in Caco-2 monolayers, unlike raw cabbage or brine.
In a study published in Applied and Environmental Microbiology, researchers tested sterile-filtered fermented cabbage homogenates on Caco-2 monolayers exposed to interferon gamma (IFN-γ) and tumor necrosis factor alpha (TNF-α), cytokines known to disrupt tight junctions. Fermented cabbage significantly preserved trans-epithelial electrical resistance (TER) and reduced paracellular permeability, as measured by FITC-dextran flux. Raw cabbage and brine preparations conferred no protection.
Both commercial and laboratory-fermented cabbage preparations, applied at 10% (vol/vol) and pH-adjusted to 7.4, maintained barrier function. This occurred despite elevated interleukin 8 (IL-8) secretion in cytokine-exposed conditions. Only commercial fermented cabbage reduced IL-8 levels modestly.
Metabolomic profiling via gas chromatography–time of flight mass spectrometry (GC-TOF/MS) and reverse-phase liquid chromatography–high-resolution tandem mass spectrometry (RP-LC-HRMS/MS) revealed 583 and 6,778 metabolites, respectively. Fermented cabbage was enriched in lactic acid, D-phenyl-lactate (D-PLA), indole-3-lactate (ILA), and γ-aminobutyric acid (GABA). Targeted analysis showed increases in D-PLA from ~6 µg/mL in raw cabbage to ~20 µg/mL in fermented samples; ILA from ~8.5 µg/mL to ~10 µg/mL; and GABA from ~167 µg/mL to ~400 µg/mL.
When tested individually, D-PLA, ILA, and lactate reduced cytokine-induced paracellular permeability but did not fully restore TER. This suggests the protective effect requires the complex metabolite mixture present in fermented cabbage.
Addition of Lactiplantibacillus plantarum NCIMB8826R to laboratory-scale ferments shifted metabolomic profiles to more closely resemble commercial sauerkraut and did not impair barrier protection.
Overall, fermentation increased levels of amino acids, organic acids, and phenolics. The authors concluded that intestinal barrier–protective compounds are consistently enriched during cabbage fermentation, regardless of scale or microbial inoculation, which may contribute to the health-promoting properties of fermented vegetables. The study was limited to in vitro models and did not assess in vivo outcomes.
No conflicts of interest were reported.