A recent review in the journal Neuroscience & Biobehavioral Reviews, authored by researchers from Ireland, delves into the diverse realm of fermented foods, exploring their sources, fermentation techniques, and the potential impact on the microbiota-gut-brain axis. This comprehensive examination aims to shed light on the mental health benefits associated with these foods while identifying existing knowledge gaps and proposing solutions to advance the understanding of their therapeutic potential.
The microbiota-gut-brain axis, a crucial mediator of external signals and intrinsic functions, plays a pivotal role in connecting the body’s various components. It involves continuous communication between the gut microbiota and the central nervous system, with factors like diet influencing this intricate network. Recent advancements have highlighted the potential of microbiota-targeted dietary interventions, including probiotics, prebiotics, and fermented foods, to positively impact mental health by modulating the gut-brain axis.
Historically, fermented foods served purposes such as prolonging storage and enhancing flavor. These foods, encompassing categories like cereal, dairy, meat, fish, vegetable, and legume, undergo unique fermentation processes, harboring rich microbial communities influenced by various factors. The researchers emphasize the potential of fermented foods to shape gut microbiota composition, produce beneficial metabolites, and modulate pathways connecting the gut and brain, making them promising candidates for dietary interventions.
The review explores how fermented foods influence the microbiota-gut-brain axis through mechanisms such as immune modulation, barrier integrity enhancement, and neuroendocrine regulation. Microbes and metabolites from fermented foods interact with receptors, impacting immune responses and potentially enhancing intestinal and blood-brain barrier integrity. The review also discusses the influence of fermented foods on the hypothalamic-pituitary-adrenal (HPA) axis and serotonin levels, showcasing their diverse immunomodulatory effects.
Fermented foods exert profound effects on the gut-brain axis by modulating the enteroendocrine system (EES) and influencing gut hormones like serotonin, neuropeptide-Y, glucagon-like peptide 1 (GLP-1), ghrelin, and somatostatin. These hormones play a crucial role in regulating motility, appetite, and insulin release, impacting feeding behavior. The review acknowledges the complexity of these interactions and the importance of understanding them to harness the potential health benefits of fermented foods.
The preclinical and clinical landscape of fermented foods is explored, showcasing behavioral improvements and microbiota alterations observed in various models, including drosophila, zebrafish, mice, and pigs. While human studies on fermented dairy yield mixed cognitive effects, observational studies link fermented food consumption to altered gut profiles and reduced anxiety. The potential cognitive benefits of fermented soy products, particularly isoflavones, are also discussed.
The review concludes by addressing future trends and challenges in the field. Standardizing fermented foods proves challenging due to diverse microbial communities influenced by various factors. Environmental conditions, fermentation duration, and substrate type contribute to this complexity. The importance of ‘omics’ techniques, such as shotgun metagenomics, for understanding and data archiving is emphasized, but challenges in effective standardization persist. Setting up human studies for fermented food interventions presents its own set of challenges, including the need for unfermented controls. Accurate measurement of fermented food intake is hindered by the diversity of recommended foods, necessitating detailed methods like 24-hour food recalls and food diaries.
In conclusion, the study underscores the substantial impact of fermented foods on health, leveraging diverse microbial strains, metabolites, and bioactive compounds to optimize neural and mental health benefits. Despite existing challenges, fermented foods emerge as pivotal components in the evolving landscape of microbiota-based therapeutics for mental health. Further human studies, with a focus on unfermented controls, are deemed necessary to comprehensively understand the beneficial impacts of fermented foods on the microbiota-gut-brain axis.
