Fermented Foods Benefits Mental Health

In a recent analysis published in the journal Neuroscience & Biobehavioral Reviews, Irish researchers investigated the variety of fermented foods, their origins, and fermentation techniques, as well as their ability to influence the microbiota-gut-brain axis. They also identified knowledge gaps and barriers in researching the mental health benefits of various fermented foods and provided methods for better understanding their therapeutic potential.

Background

Microbes that colonize the gut play an important role in the microbiota-gut-brain axis, connecting the body’s exterior signals and intrinsic activities while also communicating with the central nervous system. Diet, for example, has an impact on the gut microbiota as well as the intestinal, immune, and neurological components of the microbiota-gut-brain axis. Recent research suggests that microbiota-targeted dietary therapies, such as probiotics, prebiotics, and fermented foods, can improve mental health by altering the gut-brain axis.

Fermented foods were traditionally used to extend storage and improve flavor. They are diverse, with substrates ranging from cereal to dairy, meat, fish, vegetables, and legumes, each experiencing its own fermentation process. These meals have a diverse microbial community that is impacted by substrate type, geographical location, pH, and preparation methods, providing possible probiotics, bioactive peptides, phytochemicals, and vitamins. These foods are being investigated further by researchers because of their ability to modify gut microbiota composition, create beneficial metabolites, and modulate pathways connecting the gut and brain, making them a promising option for dietary therapies.

The current review investigates the mental health advantages of fermented foods, focusing on the microbiota-gut-brain axis and analyzing the limitations encountered in preclinical and human investigations.

Fermented Food and the Microbiota-Gut-Brain Axis

Fermented foods have an impact on the microbiota-gut-brain axis by modulating immune responses, maintaining barrier integrity, and regulating neuroendocrine function. Microbes and metabolites from these foods interact with receptors, which influence immune responses. Fermented foods improve intestine and blood-brain barrier integrity, possibly through microbial metabolites. They also affect the hypothalamic-pituitary-adrenal (HPA) axis and serotonin levels. Preclinical and human research show that fermented foods have a wide range of immunomodulatory effects, emphasizing the importance of further investigating their intricate interactions with the microbiota-gut-brain-immune axis.

Fermented foods have a substantial effect on the gut-brain axis by modulating the enteroendocrine system (EES), which influences gut hormones such as serotonin, neuropeptide-Y, glucagon-like peptide 1 (GLP-1), ghrelin, and somatostatin. These hormones control motility, hunger, and insulin release, which all influence feeding behavior. These foods high in prebiotics and probiotics modify the gut microbiota and increase the production of gut hormones, particularly GLP-1. However, research on the effect of fermented foods on satiety has yielded equivocal results, with fluctuations in hormone release identified. These foods may also affect ghrelin and leptin levels, which help regulate hunger. Understanding these intricate interactions is critical for maximizing the health advantages of fermented foods.

The preclinical and clinical landscape

Fermented foods affect gut-brain communication pathways, immunological responses, gut microbiota, microbial metabolites, and the enteric nervous system. Preclinical models of drosophila, zebrafish, mice, and pigs show behavioral improvements and microbiota changes when fermented dairy, soy, sugar-based products, and other substrates are administered. Human research on fermented dairy have conflicting cognitive effects, however observational studies relate fermented food consumption to altered gut patterns and decreased anxiety. Fermented soy products, particularly isoflavones, may improve women’s cognitive function, in contrast to negative connections with tofu consumption. A prior meta-analysis showed that fermented meals provide cognitive benefits.

Future trends and challenges

Fermented foods are difficult to standardize due to varied microbial communities impacted by geography, production scale, and substrate type. Environmental circumstances, fermentation duration, salinity, pH, moisture, and ripening time all contribute to complexity. Regulatory norms provide limited insights and require cultural sensitivity. ‘Omics’ approaches facilitate understanding and data storage, but the wide diversity of these foods necessitates more investigation for effective standardization, taking into account both bioactive potential and cultural preservation. Setting up human trials for fermented food interventions involves problems, including as accounting for controls and emphasizing the importance of unfermented controls in assessments. The wide range of foods advised makes accurate assessment of fermented food intake difficult, necessitating precise approaches such as 24-hour food recalls and food diaries. Biomarkers connected with fermented food consumption provide exact quantification, leveraging innovations such as plant metabarcoding to create unique fingerprints. Using appropriate microbiome capture methods entails prioritizing high-resolution techniques such as shotgun metagenomics above 16S rRNA (ribosomal ribonucleic acid) sequencing.

Conclusion

In conclusion, this study examines the significant impact of fermented foods on health, utilizing a variety of microbial strains, metabolites, and bioactive substances to maximize neurological and behavioral health advantages. It underlines the need for more human studies, particularly with unfermented controls, in order to fully identify and comprehend the beneficial effects of these foods on the microbiota-gut-brain axis. Despite obstacles, fermented foods are emerging as critical components in the evolution of microbiota-based therapies for mental health.

For more information: Fermented Foods: Harnessing Their Potential to Modulate The Microbiota-Gut-Brain Axis for Mental Health, Neuroscience & Behavioral Reviews, https://doi.org/10.1016/j.neubiorev.2024.105562