Traditional Asian Fermented Foods and Neuroprotection: A Narrative Review of Evidence on Neuroinflammation, Oxidative Stress, and the Microbiota–Gut–Brain Axis
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Abstract
Introduction: Neuroinflammation and oxidative stress contribute to the progression of neurodegenerative disorders. Traditional Asian fermented foods may influence these processes through microorganisms and fermentation-derived compounds acting along the microbiota–gut–brain axis (MGBA), although their clinical relevance remains uncertain. This review critically synthesised evidence concerning the potential effects of kimchi, miso, natto, and tempeh on neuroinflammation, oxidative stress, and MGBA-related pathways.
Methods: A structured narrative review was conducted using PubMed/MEDLINE, Scopus, Web of Science, Embase, and Google Scholar. Peer-reviewed publications from January 2010 to June 2025 were considered. Twenty-seven publications were included, comprising 10 primary studies and 17 reviews. Mechanistic, animal, observational, and human-intervention evidence was synthesized thematically. Evidence from whole foods was distinguished from that concerning food-derived microorganisms and isolated bioactive components.
Results: Fermented-food-associated microorganisms, short-chain fatty acids, isoflavone aglycones, GABA, and bioactive peptides may influence intestinal-barrier function, inflammatory signaling, antioxidant responses, and neurotrophic pathways. However, evidence varied substantially among foods and was derived mainly from experimental models or isolated components. Human findings were limited, heterogeneous, and largely observational. Current evidence therefore supports biological plausibility more strongly than clinical neuroprotection.
Conclusion: Future research should evaluate standardized whole-food interventions using adequate sample sizes, longer follow-up, and clinically meaningful neurological outcomes. Current evidence is insufficient to recommend these foods specifically for preventing or treating neurodegenerative disease.
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